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Objective To evaluate the safety of maternal pertussis vaccination on pregnancy and birth outcomes. Methods The study population comprised 1272 healthy nulliparous pregnant women who participated in Screening Tests to identify poor Outcomes in Pregnancy (STOP) study at two obstetric hospitals in South Australia between 2015 and 2018. Participants were followed prospectively, with vaccination (confirmed by medical records), extensive amounts of pregnancy and birth outcome data collected by research midwives. Adjusted relative risks (aRRs) and hazard ratios (aHRs) were estimated accounting for time-varying vaccine exposure and the temporal nature of each outcome. Results Of the 1272 women included in this study, 80.1% (n = 1019) received maternal pertussis vaccination. Vaccinated women had an average 0.22 weeks (95% CI 0.001, 0.44) longer gestation at delivery compared to unvaccinated women. Maternal pertussis vaccination was not associated with chorioamnionitis (aRR 0.71, 95% CI 0.27,1.82), gestational hypertension (aHR 1.24, 95% CI, 0.66, 2.30), preeclampsia (aHR 0.75, 95% CI 0.47, 1.18) nor preterm birth (aHR 0.99, 95% CI 0.47, 2.07). Neither risk of low birth weight (aHR 0.72, 95% CI 0.41, 1.27) nor small for gestational age infants (aHR 0.67,95% CI 0.29, 1.55) were increased following maternal pertussis vaccination. No associations between pertussis vaccination during pregnancy and adverse birth outcomes including admission to the neonatal care unit, low Apgar scores, and mechanical ventilation were observed. Results were not materially changed after adjustment for maternal influenza vaccination. Conclusion Our study provides reassuring evidence of the safety of maternal pertussis vaccination with no increased risk of adverse pregnancy and birth outcomes. These findings support recommendations for pertussis vaccination during pregnancy to prevent morbidity and mortality associated with early-infant pertussis disease.

Objective To identify the psychosocial factors influencing women’s uptake and willingness to receive pertussis and influenza vaccine during pregnancy. Methods The study population comprised 1364 healthy nulliparous pregnant women who participated in a prospective cohort study at two obstetric hospitals in South Australia between 2015 and 2017. Information on women's vaccination status, sociodemographic, lifestyle and psychological state were collected at 9–16 weeks’ gestation and medical case notes were checked post-delivery to verify the reported vaccination status. Poisson regression models were used to estimate the crude and adjusted prevalence ratios (aPRs) to identify psychosocial factors influencing uptake of vaccination during pregnancy. Results Willingness to receive the recommended maternal vaccines was high (90%). Overall, 79% and 48% received maternal pertussis and influenza vaccines respectively. There was no evidence to support the influence of psychosocial factors on women’s willingness to receive immunization during pregnancy. High levels of anxiety (aPR 0.98, 95% CI: 0.87–1.09) was not associated with uptake of maternal pertussis vaccine. However, elevated depressive symptoms (aPR 1.14, 95% CI: 1.00–1.30) and very high-perceived stress during pregnancy were significantly associated with receipt of pertussis vaccination (aPR 0.87; 95% CI 0.76–0.99). Women with mild depressive symptoms (aPR 1.21, 95% CI 1.00–1.44) and mild anxiety symptoms (aPR 1.21, 95% CI: 0.99–1.48) were more likely to receive influenza vaccine during pregnancy (aPR 1.27, 95% CI: 1.08–1.49). A history of major depressive disorder was independently associated with receipt of pertussis (aPR 1.16, 95% CI 1.06–1.26) and influenza vaccination during pregnancy (aPR 1.32; 95% CI 1.14–1.58). Conclusion Regardless of psychosocial factors, most women reported a positive willingness to receive the recommended vaccinations during pregnancy. However, psychosocial factors influenced the uptake of pertussis and influenza vaccines during pregnancy. Psychosocial factors should be taken into consideration in designing interventions and implementation of maternal pertussis and influenza immunization programs.

To examine the patterns and predictors of inter-pregnancy body mass index (BMI) change and its impact on perinatal outcomes in the second pregnancy.Retrospective cohort study.Tertiary teaching hospital in Adelaide, Australia.Women with their first and second consecutive, singleton deliveries occurring between 2000 and 2012 (N=5371).Inter-pregnancy weight change calculated based on difference between BMI at respective antenatal booking visits. Association between inter-pregnancy weight change and perinatal outcomes investigated using multivariate generalised linear models, with stratification according to initial maternal BMI category in first pregnancy.Gestational diabetes (GDM); pregnancy induced hypertensive disorders; small-for-gestational age (SGA); preterm birth; large-for-gestational age (LGA) and macrosomia (4500g).On average, women with a normal BMI gained 1kg/m(2) between first and second pregnancies, while women who were overweight or obese gained 1.37kg/m(2). Among women with a normal BMI in their first pregnancy, a BMI increase of ≥4kg/m(2) was associated with increased risk of developing GDM (aRR 1.97; 95% CI 1.22-3.19), a macrosomic (aRR 4.06; 95% CI 2.25-7.34) or LGA infant (aRR 1.31 0.96-1.78) in the second pregnancy, while a reduction in BMI (≤-2kg/m(2)) was associated with an increased risk of SGA (aRR 1.94; 1.19-3.16). Among women who were overweight or obese in their first pregnancy, a BMI increase of ≥2-4 and ≥4kg/m(2) was associated with increased risks of developing GDM in the second pregnancy (aRR 1.39; 95% CI 1.01-1.91 and aRR 1.64 95% CI 1.16-2.31; ptrend0.001), while no associations were observed for a BMI increase and risk of a macrosomic, SGA, or LGA infant. In contrast, reduction in BMI (≤-2kg/m(2)) was associated with a reduced risk of GDM (aRR 0.58 95% CI 0.37-0.90) and SGA (aRR 0.47; 95% CI 0.25-0.87).Increases in BMI between pregnancies is associated with an increased risk for perinatal complications, even in normal-weight women, while a reduction in BMI is associated with improved perinatal outcomes among women who are overweight/obese. Inter-pregnancy weight control is an important target to reduce the risk of an adverse perinatal outcome in a subsequent pregnancy.

Hypericum perforatum (HP; also known as St. John’s Wort) is one of the most commonly used herbal therapies in the management of depressive illness. The aim of this study was to evaluate the potential side effects of HP during pregnancy on pregnancy outcome. Using data from the Danish National Birth Cohort (DNBC), we investigated outcomes among 38 HP exposed pregnancies compared to a group of 90,128 women. Associations between HP use and gestational age, preterm birth, birth weight, malformations and Apgar scores were investigated. Preterm birth did not differ across the groups. While the prevalence of malformations in the HP exposed group was slightly higher (8.1%) than observed in the control groups (3.3%; p = 0.13), this was based on only three cases and was not of any specific pattern.

Background Our study aimed to assess the safety and protective effect of maternal influenza vaccination on pregnancy and birth outcomes. Methods The study population comprised 1253 healthy nulliparous pregnant women in South Australia between 2015 and 2018. Participants were followed prospectively, with vaccination status (confirmed by medical records), pregnancy, and birth outcome data collected by midwives. Adjusted relative risks (aRRs) and adjusted hazard ratios (aHRs) were estimated accounting for time-varying vaccine exposure and temporal nature of each outcome. Findings Maternal influenza vaccination (48%, 603 of 1253) reduced the risk for pre-delivery hospitalisation with influenza like illness (aHR 0•61; 95% CI 0•39, 0•97). Maternal influenza vaccination was not associated with spontaneous abortion (aHR 0•42, 95% CI 0•12, 1•45), chorioamnionitis (aRR 0•78, 95% CI, 0•32, 1•88), gestational hypertension (aHR 0•78, 95% CI 0•47, 1•29), pre-eclampsia (aHR 0.84, 95% CI 0•54, 1•27), gestational diabetes (aHR 1•16, 95% CI 0•82, 1•66) nor preterm birth (aHR 0•94, 95% CI 0•59, 1•49). No associations between antenatal influenza vaccination and congenital anomalies, admission to the neonatal care unit, low Apgar scores, and mechanical ventilation were observed. Results were not materially changed after adjustment for pertussis vaccination. We observed a protective effect of maternal influenza vaccination on low birth weight (aHR 0•46, 95% CI 0•23, 0•94) and a marginal protective effect on small for gestational age births (aHR 0•65, 95% CI 0•40, 1•04) during periods of high influenza activity. Interpretation These results support the safety of maternal influenza vaccination and suggest a protective effect in reducing the rates of low birthweight and small for gestational age births. Funding There was no funding for this study.

In the absence of randomised controlled trials, knowledge of outcomes associated with medication use during pregnancy is dependent on observational studies. Numerous observational study designs exist, with the decision on which is most appropriate depending on a number of factors, including the exposure and outcome under investigation and knowledge of key methodological issues. This review provides an overview of the key methodological issues involved in undertaking observational studies to investigate medication use during pregnancy, including selection bias, exposure and outcome classification, information bias, confounding and statistical analysis. This review also discusses observational study types used to investigate outcomes associated with medication use during pregnancy and summarises their relative strengths and weaknesses. Knowledge of the strengths, weaknesses and methodological issues associated with observational studies can assist clinicians in making assessments about the validity and applicability of results presented in order to provide the best recommendations to patients. Refereed/Peer-reviewed