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Maternal hypothyroidism is known to result in neurodevelopmental disorders in offspring, but whether subclinical hypothyroidism results in lower intelligence quotient (IQ) performance in progeny is an area of debate. Animal studies have shown that fetal thyroxine and triiodothyronine are primarily maternally derived before mid gestation. Other animal data reveal that fetal brain damage at a time that is analogous to the first trimester in humans can be linked to irreversible future brain damage. A large study conducted on an unselected population of pregnant women, both with known diagnosis of hypothyroidism and those who were screened but not diagnosed, found a four-point difference in the IQ levels of the offspring, raising the question of clinical significance. The endocrine community has accepted that subclinical hypothyroidism causes a significant decrease in IQ scores and has advocated for routine screening of pregnant women. However, obstetric authorities have cautioned that more research is needed before a causal relationship between subclinical hypothyroidism and lower IQ performance can be verified. Consequently, the American College of Obstetricians and Gynecologists has stated that routine screening and treatment of subclinical hypothyroidism cannot be recommended. We will review the basic science and clinical evidence for the neurodevelopmental effects of thyroid dysfunction in pregnancy. [ABSTRACT FROM AUTHOR]

Counseling regarding the options for aneuploidy risk assessment is complicated and requires thorough counseling with the patient. Second trimester serum risk assessment has been the gold standard because of widespread availability, low cost, and vast experience with counseling and performance. First trimester risk assessment is becoming more widely available and provides increased sensitivity for Down syndrome detection with a detection rate of approximately 87% (95% confidence interval: 84.0% to 89.4%), at a fixed false-positive rate of 5%. With the advent of first trimester techniques, controversy has arisen as there are advocates for the different recently available approaches. In this chapter, we outline the various options in a manner that will provide practical information for physicians offering such testing. Clearly, implementation of first trimester risk assessment requires special training and meticulous quality control standards for nuchal translucency and laboratory measurements, access to chorionic villus sampling, and also appropriate counseling regarding risk assessment options. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the risks of adverse maternal and neonatal outcomes associated with pregnancies complicated by hepatitis C virus (HCV) infection., Methods: This is a secondary analysis of a multicenter prospective cohort study of HCV infection in pregnancy. Participants were screened for HCV infection with serum antibody tests, and each participant with a positive HCV result (case group) was matched with up to two individuals with negative HCV results (control group) prospectively by gestational age (±2 weeks) at enrollment. Maternal outcomes included gestational diabetes, abruption, preeclampsia or gestational hypertension, cholestasis, and preterm delivery. Neonatal outcomes included hyperbilirubinemia, admission to neonatal intensive care (NICU); small-for-gestational-age (SGA) birth weight; and neonatal infection , defined as sepsis or pneumonia. Models were adjusted for maternal age, body mass index, injection drug use, and maternal medical comorbidities., Results: The 249 individuals in the case group were prospectively matched to 486 individuals in the control group who met eligibility criteria. There were significant differences in demographic characteristics between the groups, including race, socioeconomic markers, education, insurance status, and drug and tobacco use. The frequencies of maternal outcomes of gestational diabetes, preeclampsia, and abruption were similar between the case and control groups. Preterm birth was similar between groups, but neonates born to individuals in the case group were more likely to be admitted to the NICU (45.1% vs 19.0%, adjusted odds ratio [aOR] 2.6, 95% CI, 1.8-3.8) and to have SGA birth weights below the 5th percentile (10.6% vs 3.1%, aOR 2.9, 95% CI, 1.4-6.0). There were no increased odds of hyperbilirubinemia or neonatal infection., Conclusion: Despite no increased odds of preterm birth or other adverse maternal outcomes in adjusted analyses, maternal HCV infection was associated with twofold increased odds of NICU admission and nearly threefold increased odds of SGA birth weight below the 5th percentile., Competing Interests: Financial Disclosure Brenna Hughes reports an ongoing financial relationship with UpToDate. Rebecca Clifton reports funding from the University of Arkansas for Medical Sciences for DSMB meetings and from the NIH to her institution. Anna Bartholomew reports money paid to her institution by NICHD and George Washington University. Alan Tita reports money paid to his institution from Pfizer. Torri D. Metz received UpToDate royalties for two topics on trial of labor after cesarean. Money was paid to her institution from Pfizer (site PI for phase III respiratory syncytial virus [RSV] vaccine trial and site PI for a COVID-19 vaccination trial in pregnancy). Geeta Swamy reports receiving past funding from GlaxoSmithKline and ongoing funding from Pfizer, Medscape, UpToDate, Moderna, and Sanofi. The other authors did not disclose any potential conflicts of interest., (Copyright © 2024 by the American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To characterize breastfeeding behaviors and identify factors associated with breastfeeding initiation among people with hepatitis C virus (HCV) infection., Methods: We conducted a secondary analysis of a multicenter observational cohort of pregnant people with singleton gestations and HCV seropositivity. This analysis includes individuals with data on breastfeeding initiation and excludes those with human immunodeficiency virus (HIV) co-infection. The primary outcome was self-reported initiation of breastfeeding or provision of expressed breast milk. Secondary outcomes included duration of breastfeeding. Demographic and obstetric characteristics were compared between those who initiated breastfeeding and those who did not to identify associated factors. Univariable and multivariable analyses were performed., Results: Overall, 579 individuals (75.0% of participants in the parent study) were included. Of those, 362 (62.5%) initiated breastfeeding or provided breast milk to their infants, with a median duration of breastfeeding of 1.4 months (interquartile range 0.5-6.0). People with HCV viremia , defined as a detectable viral load at any point during pregnancy, were less likely to initiate breastfeeding than those who had an undetectable viral load (59.4 vs 71.9%, adjusted odds ratio [aOR] 0.61, 95% CI, 0.41-0.92). People with private insurance were more likely to initiate breastfeeding compared with those with public insurance or no insurance (80.0 vs 60.1%; aOR 2.43, 95% CI, 1.31-4.50)., Conclusion: Although HCV seropositivity is not a contraindication to breastfeeding regardless of viral load, rates of breastfeeding initiation were lower among people with HCV viremia than among those with an undetectable viral load., Clinical Trial Registration: ClinicalTrials.gov , NCT01959321 ., Competing Interests: Financial Disclosure Alan T.N. Tita reports money was paid to his institution from Pfizer. Torri D. Metz reports receiving royalties from UpToDate for two topics on trial of labor after cesarean delivery. Her institution received payment from Pfizer, when she was a site PI for Phase III respiratory syncytial virus (RSV) vaccine trial, and when she was a site PI for a pharmacokinetic study of Paxlovid in pregnancy for mild-to-moderate COVID-19. Geeta K Swamy reports receiving payment from GlaxoSmithKline, Pfizer, UpToDate, Sanofi, Medscape, and Moderna. The other authors did not report any potential conflicts of interest., (Copyright © 2024 by the American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To estimate the rate of perinatal transmission of hepatitis C virus (HCV) infection, to identify risk factors for perinatal transmission of HCV infection, and to determine the viremic threshold for perinatal transmission., Methods: This was a prospective, multicenter, observational study of pregnant individuals at less than 24 weeks of gestation screened for HCV infection from 2012 to 2018 in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. Individuals found to be HCV antibody-positive were followed throughout pregnancy. Children were followed for evidence of perinatal transmission at 2-6 months (HCV RNA testing) and at 18-24 months (HCV RNA and antibody testing) of life. The primary outcome was perinatal transmission, defined as positive test results at either follow-up time point., Results: A total of 109,379 individuals were screened for HCV infection. Of the 1,224 participants who screened positive, 772 (63.1%) enrolled and 432 of those 772 (56.0%) had data available to assess primary outcome. The overall rate of perinatal transmission was 6.0% (26/432, 95% CI 4.0-8.7%). All children with HCV infection were born to individuals with demonstrable viremia. In viremic participants (n=314), the perinatal transmission rate was 8.0% (95% CI 5.2-11.5%). Risk factors for perinatal transmission included HCV RNA greater than 106 international units/mL (adjusted odds ratio [aOR] 8.22, 95% CI 3.16-21.4) and vaginal bleeding reported at any time before delivery (aOR 3.26, 95% CI 1.32-8.03). A viremic threshold for perinatal transmission could not be established., Conclusion: Perinatal transmission of HCV infection was limited to viremic individuals. High viral loads and antepartum bleeding were associated with perinatal transmission., Competing Interests: Financial Disclosure Mona Prasad served on the medical advisory board for Gilead. Brenna Hughes disclosed receiving payment from UpToDate and the Johns Hopkins DSMB. Ana Puga disclosed that she is cochair of the Broward County Perinatal HIV Network (no compensation) and a full-time employee of ViiV Healthcare since 2018. Torri D. Metz disclosed receiving UpToDate royalties for two topics on trial of labor after cesarean. Her institution received payment from Gestvision for her being a site PI for a preeclampsia point-of-care test (institution received money to conduct study [ended August 2020]) and from Pfizer for being a site PI for a Phase III respiratory syncytial virus (RSV) vaccine trial (institution received money to conduct the study). She has been a member of the medical advisory board for Pfizer, a site PI for a COVID-19 vaccination trial, and has served on the Board of Directors for the Society for Maternal-Fetal Medicine. Geeta Swamy reports money was paid to her from GlaxoSmithKline, Pfizer, and WebMD/Medscape. Andrew Wiznia received payment for a consultancy with Janssen Pharmaceuticals, where he has been a chairperson of the Independent Data Safety Monitoring Board. He has also received payment from Merck for a consultancy and protocol development. The other authors did not report any potential conflicts of interest., (Copyright © 2023 by the American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To evaluate the association between maternal and delivery characteristics and self-reported perceived control during childbirth., Methods: A secondary analysis of a multicenter randomized trial was conducted to compare labor induction at 39 weeks of gestation with expectant management in low-risk nulliparous people. Six to 96 hours after delivery, participants who experienced labor completed the Labor Agentry Scale, a validated self-administered questionnaire to ascertain perceived control during childbirth. Scores range from 29 to 203, with higher scores indicating a sense of greater control. Multivariable linear regression was used to determine which maternal and delivery characteristics were associated with the Labor Agentry Scale score. Eligible characteristics included age, self-reported race and ethnicity, marital status, employment status, type of insurance, previous pregnancy loss before 20 weeks of gestation, body mass index (BMI), smoking, alcohol use, mode of delivery, labor pain (0-10 points), and a composite of perinatal death or severe neonatal complications. Significant variables ( P <.05) were retained in the final multivariable model, and adjusted mean differences (95% CIs) between groups were estimated., Results: Of 6,106 people enrolled in the trial, 6,038 experienced labor, of whom 5,750 (95.2%) completed the Labor Agentry Scale and were included in this analysis. Mean [95% CI] adjusted Labor Agentry Scale scores were significantly lower among those who identified as Asian (-6.4 [-10.5 to -2.3]) or Hispanic (-3.7 [-5.7 to -1.7]) compared with White, smoked compared with did not smoke (-2.8 [-5.5 to -0.1]), had BMIs of 35 or higher compared with less than 30 (-2.0 [-3.8 to -0.2]), were unemployed (-3.15 [-4.76 to -1.55]), did not have private health insurance (-2.61 [-4.47 to -0.76]), underwent operative vaginal (-5.1 [-7.7 to -2.6]) or cesarean (-14.4 [-16.1 to -12.6]) delivery compared with spontaneous vaginal delivery, and reported greater labor pain score of 8 or higher compared with less than 8 (-11.9 [-13.4 to -10.4]). Mean [95% CI] adjusted Labor Agentry Scale scores were significantly higher among people who were employed compared with unemployed (3.2 [1.6-4.8]) and had private compared with nonprivate insurance (2.6 [0.76-4.5])., Conclusion: In nulliparous people at low risk, unemployment, lack of private health insurance, Asian race, Hispanic ethnicity, smoking, operative delivery, and more labor pain were associated with lower perceived control during labor., Clinical Trial Registration: ClinicalTrials.gov , NCT01990612., Competing Interests: Financial Disclosure Alan T.N. Tita disclosed that money was paid to his institution from Pfizer. Geeta K. Swamy disclosed that she received payment from GlaxoSmithKline, Pfizer, and UpToDate. She has also been a consultant for Moderna. The other authors did not report any potential conflicts of interest., (Copyright © 2023 by the American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To evaluate whether a synthetic osmotic cervical dilator is noninferior to oral misoprostol for cervical ripening., Methods: In an open-label, noninferiority randomized trial, pregnant women undergoing induction of labor at 37 weeks of gestation or more with Bishop scores less than 6 were randomized to either mechanical cervical dilation or oral misoprostol. Participants in the mechanical dilation group underwent insertion of synthetic osmotic cervical dilator rods, and those in the misoprostol group received up to six doses of 25 micrograms orally every 2 hours. After 12 hours of ripening, oxytocin was initiated, with artificial rupture of membranes. Management of labor was at the physician's discretion. The primary outcome was the proportion of women achieving vaginal delivery within 36 hours of initiation of study intervention. Secondary outcomes included increase in Bishop score, mode of delivery, induction-to-delivery interval, total length of hospital stay, and patient satisfaction. On the basis of a noninferiority margin of 10%, an expected primary outcome frequency of 65% for misoprostol and 71% for mechanical methods, and 85% power, a sample size of 306 participants was needed., Results: From November 2018 through January 2021, 307 women were randomized, with 151 evaluable participants in the synthetic osmotic cervical dilator group and 152 in the misoprostol group (there were four early withdrawals). The proportion of women achieving vaginal delivery within 36 hours was higher with mechanical cervical dilation compared with misoprostol (61.6% vs 59.2%), with an absolute difference of 2.4% (95% CI -9% to 13%), indicating noninferiority for the prespecified margin. No differences were noted in the mode of delivery. Tachysystole was more frequent in the misoprostol group (70 [46.4%] vs 35 [23.3%]; P=.01). Participants in the synthetic osmotic cervical dilator group reported better sleep, less unpleasant abdominal sensations, and lower pain scores (P<.05)., Conclusion: Synthetic osmotic cervical dilator is noninferior to oral misoprostol for cervical ripening. Advantages of synthetic osmotic cervical dilator include a better safety profile and patient satisfaction, less tachysystole, lower pain scores, and U.S. Food and Drug Administration approval., Clinical Trial Registration: ClinicalTrials.gov, NCT03670836., Funding Source: Medicem Technology s.r.o., Czech Republic., Competing Interests: Financial Disclosure The authors did not report any potential conflicts of interest., (Copyright © 2022 by the American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To compare health care medical resource utilization in low-risk nulliparous pregnancies according to body mass index (BMI, calculated as weight in kilograms divided by height in meters squared) categories., Methods: This is a secondary analysis of a multicenter randomized controlled trial of induction of labor between 39 0/7 39 and 4/7 weeks of gestation compared with expectant management in low-risk nulliparous pregnant people, defined as those without standard obstetric indications for delivery at 39 weeks. Body mass index at randomization was categorized into four groups (lower than 25, 25-29, 30-39, and 40 or higher). The primary outcome of this analysis was time spent in the labor and delivery department from admission to delivery. Secondary outcomes included length of stay (LOS) postdelivery, total hospital LOS, and antepartum, intrapartum, and postpartum resource utilization, which were defined a priori. Multivariable generalized linear modeling and logistic regressions were performed, and 99% CIs were calculated., Results: A total of 6,058 pregnant people were included in the analysis; 640 (10.6%) had BMIs of lower than 25, 2,222 (36.7%) had BMIs between 25 and 29, 2,577 (42.5%) had BMIs of 30-39, and 619 (10.2%) had BMIs of 40 or higher. Time spent in the labor and delivery department increased from 15.1±9.2 hours for people with BMIs of lower than 25 to 23.5±13.6 hours for people with BMIs of 40 or higher, and every 5-unit increase in BMI was associated with an average 9.8% increase in time spent in the labor and delivery department (adjusted estimate per 5-unit increase in BMI 1.10, 99% CI 1.08-1.11). Increasing BMI was not associated with an increase in antepartum resource utilization, except for blood tests and urinalysis. However, increasing BMI was associated with higher odds of intrapartum resource utilization, longer total hospital LOS, and postpartum resource utilization. For example, every 5-unit increase in BMI was associated with an increase of 26.1% in the odds of antibiotic administration, 57.6% in placement of intrauterine pressure catheter, 5.1% in total inpatient LOS, 31.0 in postpartum emergency department visit, and 23.9% in postpartum hospital admission., Conclusion: Among low-risk nulliparous people, higher BMI was associated with longer time from admission to delivery, total hospital LOS, and more frequent utilization of intrapartum and postpartum resources., Clinical Trial Registration: ClinicalTrials.gov, NCT01990612., Competing Interests: Financial Disclosure Geeta K. Swamy reports that money was paid to them for consultant activities from GlaxoSmithKline, Pfizer, and Moderna for vaccine-related activities and UpToDate contributions. Hyagriv N. Simhan is a co-founder of Naima Health, LLC. The authors did not report any potential conflicts of interest., (Copyright © 2022 by the American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To study the association between nicotine or cannabis metabolite presence in maternal urine and child neurodevelopmental outcomes., Methods: We conducted a secondary analysis of two parallel multicenter randomized controlled trials of treatment for hypothyroxinemia or subclinical hypothyroidism among pregnant individuals enrolled at 8-20 weeks of gestation. All maternal-child dyads with a maternal urine sample at enrollment and child neurodevelopmental testing were included (N=1,197). Exposure was urine samples positive for nicotine (cotinine) or cannabis 11-nor-9-carboxy-delta-9-tetrahydrocannabinol [THC-COOH]) or both metabolites. Primary outcome was child IQ at 60 months. Secondary outcomes included cognitive, motor and language, attention, behavioral and social competency, and differential skills assessments at 12, 24, 36, and 48 months. Quantile regression analysis was performed with confounder adjustment., Results: Of 1,197 pregnant individuals, 99 (8.3%) had positive cotinine samples and 47 (3.9%) had positive THC-COOH samples; 33 (2.8%) were positive for both. Groups differed in self-reported race and ethnicity, education, marital status, insurance, and thyroid status. Median IQ was similar between cotinine-exposed and -unexposed children (90 vs 95, adjusted difference in medians -2.47, 95% CI -6.22 to 1.29) and THC-COOH-exposed and -unexposed children (89 vs 95, adjusted difference in medians -1.35, 95% CI -7.76 to 5.05). In secondary outcome analysis, children with THC-COOH exposure compared with those unexposed had higher attention scores at 48 months of age (57 vs 49, adjusted difference in medians 6.0, 95% CI 1.11-10.89)., Conclusions: Neither prenatal nicotine nor cannabis exposure was associated with a difference in IQ. Cannabis exposure was associated with worse attention scores in early childhood. Longitudinal studies assessing associations between child neurodevelopmental outcomes and prenatal nicotine and cannabis exposure with a focus on timing and quantity of exposure are needed., Clinical Trial Registration: ClinicalTrials.gov, NCT00388297., Competing Interests: Financial Disclosure This study was funded in part by the University of Utah School of Medicine H.A. and Edna Benning Presidential Endowment. Dr. Smid serves as a medical consultant for Gilead Science Inc for hepatitis C treatment in pregnancy. Dr. Metz reports receiving UpToDate royalties for two topics on VBAC, and serving as a medical consultant to Pfizer for design of a SARS-CoV-2 vaccination trial in pregnancy. Funds for Dr. Metz were paid to her institution from Pfizer for being a site PI for an RSV vaccine trial. Funds were paid to her institution from Gestvision (site PI for preeclampsia POC test). Dr. Metz and Smid also report money was paid to her institution from NIDA. Dr. Tita reports support from NIH/NCATS and money was paid to his institution from Pfizer for a vaccine study and the CDC. Dr. Miller reports money was paid to her institution from Pfizer as a site PI for a study on COVID vaccine in pregnancy. The authors did not report any potential conflicts of interest., (Copyright © 2021 by the American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To evaluate race and ethnicity differences in cesarean birth and maternal morbidity in low-risk nulliparous people at term., Methods: We conducted a secondary analysis of a randomized trial of expectant management compared with induction of labor in low-risk nulliparous people at term. The primary outcome was cesarean birth. Secondary outcome was maternal morbidity, defined as: transfusion of 4 or more units of red blood cells, any transfusion of other products, postpartum infection, intensive care unit admission, hysterectomy, venous thromboembolism, or maternal death. Multivariable modified Poisson regression was used to evaluate associations between race and ethnicity, cesarean birth, and maternal morbidity. Indication for cesarean birth was assessed using multivariable multinomial logistic regression. A mediation model was used to estimate the portion of maternal morbidity attributable to cesarean birth by race and ethnicity., Results: Of 5,759 included participants, 1,158 (20.1%) underwent cesarean birth; 1,404 (24.3%) identified as non-Hispanic Black, 1,670 (29.0%) as Hispanic, and 2,685 (46.6%) as non-Hispanic White. Adjusted models showed increased relative risk of cesarean birth among non-Hispanic Black (adjusted relative risk [aRR] 1.21, 95% CI 1.03-1.42) and Hispanic (aRR 1.26, 95% CI 1.08-1.46) people compared with non-Hispanic White people. Maternal morbidity affected 132 (2.3%) individuals, and was increased among non-Hispanic Black (aRR 2.05, 95% CI 1.21-3.47) and Hispanic (aRR 1.92, 95% CI 1.17-3.14) people compared with non-Hispanic White people. Cesarean birth accounted for an estimated 15.8% (95% CI 2.1-48.7%) and 16.5% (95% CI 4.0-44.0%) of excess maternal morbidity among non-Hispanic Black and Hispanic people, respectively., Conclusion: Non-Hispanic Black and Hispanic nulliparous people who are low-risk at term undergo cesarean birth more frequently than low-risk non-Hispanic White nulliparous people. This difference accounts for a modest portion of excess maternal morbidity., Competing Interests: Financial Disclosure Geeta K. Swamy reports money was paid to them from GlaxoSmithKline, Pfizer, Moderna, and UpToDate (contributor). Money was paid to their institution from the CDC. The other authors did not report any potential conflicts of interest., (Copyright © 2021 by the American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.)

Increasing ability to diagnose fetal single gene disorders has changed the prenatal diagnostic paradigm. As fetal sequencing advances, the genomic information obtained can lead to improved prognostic counseling, and elucidation of recurrence risk and future prenatal diagnosis options. For some of these disorders, postnatal molecular therapy, including gene therapy, is available or being studied in clinical trials. Most of the initial research and clinical trials have involved children and adults, but there are potential benefits to treating conditions before birth. Many clinical studies are underway exploring the potential for in utero gene therapy., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To compare maternal and neonatal outcomes after preterm prelabor rupture of membranes (PROM) from 23 to 34 weeks of gestation in twin compared with singleton gestations., Methods: We conducted a secondary analysis of an obstetric cohort of 115,502 individuals and their singleton or twin neonates born in 25 hospitals nationwide (2008-2011). Those with preterm PROM from 23 0/7 through 33 6/7 weeks of gestation were included; neonates with major fetal anomalies were excluded. The coprimary outcomes for this analysis were composite maternal morbidity (chorioamnionitis, blood transfusion, postpartum endometritis, wound infection, sepsis, venous thromboembolism, intensive care unit admission, or death) and composite major neonatal morbidity (persistent pulmonary hypertension, intraventricular hemorrhage grade III or IV, seizures, hypoxic-ischemic encephalopathy, necrotizing enterocolitis stage II or III, bronchopulmonary dysplasia, stillbirth subsequent to admission, or neonatal death before discharge). Logistic regression was used to estimate unadjusted and adjusted odds ratios (ORs) with 95% CIs for twin compared with singleton gestations., Results: Of 1,531 (1.3%) individuals who met eligibility criteria for this analysis, 218 (14.2%) had twin gestations. The median gestational age at preterm PROM was similar between those with twins and singletons (31.2 weeks [interquartile range 27.4-32.9] vs 30.6 weeks [interquartile range 26.9-32.7], P=.23); however, those with twin gestations had a shorter median latency period (2.0 days [interquartile range 1.0-5.0] vs 3.0 days [interquartile range 2.0-8.0], P<.001). After adjustment for potential confounders, odds of experiencing composite maternal morbidity (17.9% vs 19.3%, adjusted OR 0.97, 95% CI 0.66-1.42) or composite neonatal morbidity (20.4% vs 20.5%, OR 0.97, 95% CI 0.72-1.31) did not differ between groups., Conclusion: In a large, diverse cohort, the likelihood of composite maternal or neonatal morbidity per fetus after preterm PROM was similar for twin and singleton gestations., Competing Interests: Financial Disclosure Mona Prasad reports receiving money from Gilead for a medical consultancy. Alan T. N. Tita reports money was paid to his institution from the CDC and Pfizer (vaccine study). The other authors did not report any potential conflicts of interest., (Copyright © 2021 by the American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To assess the relationship between economic vulnerability during pregnancy and childhood neurodevelopment., Methods: This is a secondary analysis of two parallel multicenter, randomized, controlled trials of administration of levothyroxine to pregnant individuals with subclinical hypothyroidism or hypothyroxinemia in the United States. All participants who delivered a live, nonanomalous neonate and completed the WPPSI-III (Weschler Preschool & Primary Scale of Intelligence) at 5 years of life and the Bayley-III (Bayley Scales of Infant Development) test at 2 years were included. The primary outcome is WPPSI-III score. Secondary outcome included Bayley-III subtest scores. Multivariable analyses were used to assess the relationships between economic vulnerability during the index pregnancy-defined as a household income less than 200% of the estimated federal poverty level, part-time or no employment, and use of government insurance-and the prespecified outcomes. Tests of interaction were performed to assess whether the magnitude of association differed according to whether participants were married or completed more than a high school education. A sensitivity analysis was performed to limit the income criteria for economic vulnerability to household income of less than 100% of the estimated federal poverty level., Results: Of 955 participants who met inclusion criteria, 406 (42.5%) were considered economically vulnerable. In bivariate analysis, the WPPSI-III score and Bayley-III subtest scores were significantly lower among children of the economically vulnerable. For the WPPSI-III, Bayley-III cognitive subtest, and Bayley-III language subtest scores, the associations between economic vulnerability and lower childhood neurodevelopmental scores were primarily seen only among those who were married or completed more than a high school education (P for interaction<.05). A similar pattern was noted when restricting the income criteria for economic vulnerability to less than 100% of the federal poverty level., Conclusion: Economic vulnerability during pregnancy is associated with an increased risk of adverse neurodevelopmental outcomes in their children at 2 and 5 years of life, particularly among those who are married or completed more than a high school education., Competing Interests: Financial Disclosure The authors did not report any potential conflicts of interest., (Copyright © 2021 by the American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To evaluate whether breastfeeding and its duration are associated with a reduced risk of low IQ scores or other neurodevelopmental problems., Methods: We conducted a secondary analysis of two parallel multicenter, double-blinded randomized controlled trials in which participants with a singleton pregnancy and either subclinical hypothyroidism or hypothyroxinemia were treated with thyroxine or placebo. Our primary outcome was a low IQ score (less than 85 on the WPPSI-III [Wechsler Preschool and Primary Scale of Intelligence III] at age 5 years). Secondary outcomes included performance measures on other validated neurodevelopmental tests. Univariable and multivariable analyses were performed to evaluate the association between breastfeeding and neurodevelopmental outcomes. Stepwise backward proceeding linear and logistic regression models were used to develop the final adjusted models., Results: Of the 772 participants studied, 614 (80%) reported breastfeeding. Of these, 31% reported breastfeeding for less than 4 months, 19% for 4-6 months, 11% for 7-9 months, 15% for 10-12 months and 23% for more than 12 months. IQ scores were available for 756 children; mean age-5 scores were higher with any breastfeeding (96.7±15.1) than without (91.2±15.0, mean difference 5.5, 95% CI 2.8-8.2), and low IQ scores were less frequent with any breastfeeding (21.5%) than with no breastfeeding (36.2%, odds ratio 0.48, 95% CI 0.33-0.71). In adjusted analyses, breastfeeding remained associated with reduced odds of low IQ score (adjusted odds ratio [aOR] 0.62, 95% CI 0.41-0.93), and each additional month of breastfeeding was associated with lower odds of a low IQ scores (aOR 0.97, 95% CI 0.939-0.996). No significant associations between breastfeeding and other neurodevelopmental outcomes were identified in adjusted analyses., Conclusion: Breastfeeding and its duration are associated with lower odds of low IQ score at age 5 years., Competing Interests: Financial Disclosure The authors did not report any potential conflicts of interest., (Copyright © 2021 by the American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To compare risks of maternal and perinatal outcomes by completed week of gestation from 39 weeks in low-risk nulliparous patients undergoing expectant management., Methods: We conducted a secondary analysis of a multicenter randomized trial of elective induction of labor at 39 weeks of gestation compared with expectant management in low-risk nulliparous patients. Participants with nonanomalous neonates, who were randomized to and underwent expectant management and attained 39 0/7 weeks of gestation, were included. Delivery gestation was categorized by completed week: 39 0/7-39 6/7 (39 weeks), 40 0/7-40 6/7 (40 weeks), and 41 0/7-42 2/7 (41-42 weeks) (none delivered after 42 2/7). The coprimary outcomes were cesarean delivery and a perinatal composite (death, respiratory support, 5-minute Apgar score 3 or less, hypoxic ischemic encephalopathy, seizure, sepsis, meconium aspiration syndrome, birth trauma, intracranial or subgaleal hemorrhage, or hypotension requiring vasopressor support). Other outcomes included a maternal composite (blood transfusion, surgical intervention for postpartum hemorrhage, or intensive care unit admission), hypertensive disorders of pregnancy, peripartum infection, and neonatal intermediate or intensive care unit admission. For multivariable analysis, P<.0125 was considered to indicate statistical significance for the coprimary outcomes., Results: Of 2,502 participants who underwent expectant management, 964 (38.5%) delivered at 39 weeks of gestation, 1,111 (44.4%) at 40 weeks, and 427 (17.1%) at 41-42 weeks. The prevalence of medically indicated delivery was 37.9% overall and increased from 23.8% at 39 weeks of gestation to 80.3% at 41-42 weeks. The frequency of cesarean delivery (17.3%, 22.0%, 37.5%; P<.001) and the perinatal composite (5.1%, 5.9%, 8.2%; P=.03) increased with 39, 40, and 41-42 weeks of gestation, respectively, and hypertensive disorders of pregnancy decreased (16.4%, 12.1%, 10.8%, P=.001). The adjusted relative risk, 95% CI (39 weeks as referent) was significant for cesarean delivery at 41-42 weeks of gestation (1.93, 1.61-2.32) and for hypertensive disorders of pregnancy at 40 weeks (0.71, 0.58-0.88) and 41-42 weeks (0.61, 0.45-0.82). None of the other outcomes were significant., Conclusion: In expectantly managed low-risk nulliparous participants, the frequency of medically indicated induction of labor, and the risks of cesarean delivery but not the perinatal composite outcome, increased significantly from 39 to 42 weeks of gestation., Competing Interests: Financial Disclosure Robert M. Silver disclosed that he is a consultant for Gestvision. Alan T.N. Tita, Edward K. Chien and Hyagriv N. Simhan disclosed that money was paid to his institution for industry research studies for clinical trials. Hyagriv N. Simhan disclosed that he is a cofounder of Naima Health, LLC. Geeta K. Swamy disclosed receiving funding from GlaxoSmithKline and Pfizer. George Saade disclosed that he is a consultant for Medicem. The other authors did not report any potential conflicts of interest., (Copyright © 2021 by the American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To develop models to predict vaginal delivery in low-risk, nulliparous women contemplating elective induction of labor or expectant management at 39 weeks of gestation., Methods: We conducted a secondary analysis of a randomized controlled trial of planned elective induction of labor at 39 weeks of gestation compared with expectant management for low-risk nulliparous women. Two groups were included for this analysis: 1) women who were randomized to the induction of labor group and underwent elective induction at 39 0/7-39 4/7 weeks of gestation and 2) women who were randomized to the expectant management group who experienced spontaneous labor or medically indicated delivery (including postterm). Multivariable logistic regression models were developed for each group using patient characteristics that would be available at the time of counseling. Model selection was based on k-fold cross-validation using backward elimination and variables that remained significant at P<.05 were retained. To compare estimated with observed rates, the elective induction of labor model was then applied to each woman in both groups to estimate individualized predicted probabilities of vaginal delivery with elective induction of labor., Results: Of 6,106 women enrolled in the trial, 4,661 met criteria for this analysis. Vaginal delivery occurred in 80.6% of the 2,153 women in the elective induction of labor group and 77.2% of the 2,508 women in the expectant management group (P=.005). The final elective induction of labor model included age, height, weight, and modified Bishop score (area under the receiver operating characteristic curve [AUROC] 0.72, 95% CI 0.70-0.75). The same variables were included in the final expectant management model (AUROC 0.70, 95% CI 0.67-0.72). Across the range of predicted probability deciles derived from the elective induction of labor model, almost all women who underwent elective induction of labor at 39 weeks of gestation had a higher observed chance of vaginal delivery than expectant management., Conclusion: Irrespective of the individual predicted chance of vaginal delivery from elective induction of labor at 39 weeks of gestation, vaginal delivery is generally more frequent if elective induction of labor is undertaken rather than expectant management. These data can be used to counsel nulliparous women regarding their "customized" chances of vaginal delivery as they choose between elective induction of labor or expectant management at 39 weeks of gestation., Clinical Trial Registration: ClinicalTrials.gov, NCT01990612.

Objective: To evaluate characteristics associated with adverse outcomes in low-risk nulliparous women randomized to elective labor induction at 39 weeks of gestation or expectant management., Methods: We conducted a secondary analysis of women randomized during the 38th week to induction at 39 weeks of gestation or expectant management. Deliveries before 39 weeks of gestation and those not adherent to study protocol or with fetal anomalies were excluded. A composite of adverse outcomes (perinatal death or severe neonatal complications), third- or fourth-degree lacerations, and postpartum hemorrhage were evaluated. Log binomial regression models estimated relative risks and 95% CIs for associations of outcomes with patient characteristics including randomly assigned treatment group. Interactions between patient characteristics and treatment group were tested., Results: Of 6,096 women with outcome data, 5,007 (82.1%) met criteria for inclusion in this analysis. Frequency of the perinatal composite was 252 (5.0%), 166 (3.3%) for third- or fourth-degree perineal laceration, and 237 (4.7%) for postpartum hemorrhage. In multivariable analysis, intended labor induction at 39 weeks of gestation was associated with a reduced perinatal composite outcome (4.1% vs 6.0%; adjusted relative risk [aRR] 0.71; 95% CI 0.55-0.90), whereas increasing body mass index (BMI) was associated with an increased perinatal composite outcome (aRR 1.04/unit increase; 95% CI 1.02-1.05). Decreased risk of third- or fourth-degree perineal laceration was observed with increasing BMI (aRR 0.96/unit increase; 95% CI 0.93-0.98) and in Black women compared with White women (1.2% vs 3.9%; aRR 0.34; 95% CI 0.19-0.60). Increased risk of postpartum hemorrhage was observed in Hispanic women compared with White women (6.3% vs 4.0%; aRR 1.64; 95% CI 1.18-2.29). Patient characteristics associated with adverse outcomes were similar between treatment groups (P for interaction >.05)., Conclusion: Compared with expectant management, intended induction at 39 weeks of gestation was associated with reduced risk of adverse perinatal outcome. Patient characteristics associated with adverse outcomes were few and similar between groups., Clinical Trial Registration: ClinicalTrials.gov, NCT01990612.

Objective: To estimate whether the frequency of adverse maternal and neonatal outcomes differs between low-risk nulliparous and multiparous women at 39-41 weeks of gestation., Methods: This is a secondary analysis of an observational obstetrics cohort of maternal-neonatal dyads at 25 hospitals. Low-risk women with nonanomalous singletons who delivered between 39 0/7 and 41 6/7 weeks of gestation were included. The composite neonatal adverse outcome included 5-minute Apgar score less than five, ventilator support or cardiopulmonary resuscitation, seizure, hypoxic ischemic encephalopathy, sepsis, bronchopulmonary dysplasia, persistent pulmonary hypertension, necrotizing enterocolitis, birth injury or perinatal death. The composite maternal adverse outcome included infection, third- or fourth-degree perineal laceration, thromboembolism, transfusion of blood products, or maternal death. Small for gestational age (SGA), large for gestational age (LGA), and shoulder dystocia requiring maneuvers were also evaluated. Multivariable regression was used to estimate adjusted relative risks (aRRs) and adjusted odds ratios (aORs) with 95% CIs., Results: Of the 115,502 women in the overall cohort, 39,870 (34.5%) met eligibility criteria for this analysis; 18,245 (45.8%) were nulliparous. The risk of the composite neonatal adverse outcome (1.5% vs 1.0%, aRR 1.80, 95% CI 1.48-2.19), composite maternal adverse outcome (15.1% vs 3.3%, aRR 5.04, 95% CI 4.62-5.49), and SGA (8.9% vs 5.8%, aOR 1.45, 95% CI 1.33-1.57) was significantly higher in nulliparous than multiparous patients. The risk of LGA (aOR 0.65, 95% CI 0.60-0.71) and shoulder dystocia with maneuvers (aRR 0.68, 95% CI 0.60-0.77) was significantly lower in nulliparous rather than multiparous patients., Conclusion: The risk of composite adverse outcomes and SGA among low-risk nulliparous women at 39-41 weeks of gestation is significantly higher than among multiparous counterparts. However, nulliparous women had a lower risk of shoulder dystocia with maneuvers and LGA.

Objective: To estimate alcohol, tobacco, and recreational drug use during pregnancy among nulliparous women., Methods: In a cohort of nulliparous women followed through pregnancy from the first-trimester nuMoM2b (Nulliparous Outcomes in Pregnancy: Monitoring Mothers to be) study, self-reported use of alcohol, tobacco, and drugs was chronicled longitudinally at four study visits in this secondary analysis. Rates of use before pregnancy, in each trimester (visit 1, visit 2, visit 3, approximating each trimester), and at the time of delivery (visit 4) were recorded. The amount of alcohol, tobacco, and drug exposure were recorded using validated measures, and trends across pregnancy were analyzed., Results: Of the 10,038 study participants, 10,028 had information regarding alcohol, tobacco, and drug use at visit 1, 9,412 at visit 2, 9,217 at visit 3, and 7,167 at visit 4. The rates of drinking alcohol, which had been 64.6% in the 3 months before pregnancy, were lower in pregnancy (3.9% at visit 1, 5.6% at visit 2, 7.0% at visit 3, and 6.1% at visit 4, P<.001 for all). Rates later in pregnancy were all greater than in the first trimester (P<.01). The rate of smoking in the 3 months before pregnancy, which was 17.8%, also declined at visit 1 (5.9%), and continued to decline through pregnancy (5.3% at visit 2, 4.7% at visit 3, and 3.9% at visit 4, with all rates lower than that of visit 1 [P<.01]). Although recreational drug use was relatively common in the months before pregnancy (33.8%), it also declined during pregnancy (1.1% at visit 2, 0.7% at visit 3, 0.4% at visit 4)., Conclusions: In this geographically and ethnically diverse cohort of nulliparous women, rates of self-reported alcohol, smoking, and recreational drug use were all significantly lower during than before pregnancy. Nonetheless, rates of alcohol use rose as pregnancy progressed, highlighting the need for continued counseling throughout all trimesters of pregnancy., Clinical Trial Registration: ClinicalTrials.gov, NCT01322529.