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Objective: To describe the relationship between a short interpregnancy interval and adverse pregnancy outcomes in the population undergoing assisted reproductive technology., Methods: This is a retrospective analysis using data from the Society for Assisted Reproductive Technology Clinic Outcome Reporting System. The cohort includes patients with a history of live birth from assisted reproductive technology who returned for a fresh, autologous in vitro fertilization (IVF) cycle from 2004 to 2013. Interpregnancy interval was defined as the interval from live birth to cycle start. Logistic regression models of preterm delivery (less than 37 weeks of gestation) and low birth weight (less than 2,500 g) on interpregnancy interval were fit with adjustment for age, body mass index, and history of preterm delivery. Predicted probabilities were generated from the logistic model., Results: Of 51,997 fresh IVF cycles after an index live birth, 17,536 resulted in a repeat live birth with 11,271 singleton live births from autologous IVF. An interpregnancy interval of less than 18 months occurred in 40.9% of cycles. Compared with a reference interpregnancy interval of 12 to less than 18 months, the adjusted odds ratio for singleton preterm delivery was 1.66 (95% CI 1.05-2.65) for an interpregnancy interval less than 6 months and 1.34 (95% CI 1.06-1.69) for 6 to less than 12 months. An interpregnancy interval 6 to less than 12 months was associated with a 3.0% increase in preterm delivery (13.6±1.1% vs 10.6±0.7%, P=.030) and a 2.7% increase in low birth weight (8.0±0.9% vs 5.3±0.5%, P=.025) compared with an interpregnancy interval of 12 to less than 18 months., Conclusion: In this nationally representative population, an interval from delivery to treatment start of less than 12 months is associated with increased rates of preterm delivery and low birth weight in singleton live births from assisted reproductive technology. The data support delaying the start of IVF treatment 12 months from a live birth, but do not suggest a benefit from a longer interval as has been recommended for naturally conceiving couples.

Objective: To estimate the effect of ethnicity on in vitro fertilization (IVF) outcomes after blastocyst transfer., Methods: We conducted a review of fresh blastocyst transfer IVF cycles from January 1, 2005, to December 31, 2006. Data collection included demographic information, infertility history, treatment protocol details, and treatment outcomes. Statistics were performed using the Student t test and chi2 test. To establish the independent contribution of Asian ethnicity, a multivariable logistic regression analysis was performed., Results: We reviewed 180 blastocyst transfer cycles among white (62%) and Asian (38%) women. The groups were similar in most baseline characteristics. Asian women, however, had a lower body mass index (22.6 compared with 24.2, P=.02), were more likely to be nulligravid (53% compared with 35%, P=.03), and were more likely to have had at least one prior IVF cycle (37% compared with 20%, P=.02) The groups were similar in treatment characteristics, number of oocytes retrieved, fertilization rate, and number of blastocysts transferred. However, Asian women had a thicker endometrial lining (10.9 compared with 10.2, P=.02). Despite these similarities, Asian women had a lower implantation rate (28% compared with 45%, P=.01), clinical pregnancy rate (43% compared with 59%, P=.03), and live birthrate (31% compared with 48%, P=.02). In multivariable analysis, the decreased live birthrate among Asian women persisted (adjusted odds ratio 0.48, 95% confidence interval 0.24-0.96, P=.04)., Conclusion: When compared with white women, Asian women have lower clinical pregnancy and live birthrates after blastocyst transfer.

In order to delineate factors contributing to variation in hormone levels, progesterone and prolactin (PRL) levels from 28 normal women, obtained daily during one menstrual cycle and every 20 minutes during a midluteal 24-hour admission in a subgroup of five subjects, provided a data base for analysis of these variables. Pulsatile analysis of the 24-hour data was conducted using an adaptive-threshold algorithm, and normal reference ranges were generated from randomly selected daily hormone values. Our data verify that inherent variation can significantly alter single random serum levels of reproductive hormones. These variations included menstrual cycle day, circadian influence, pulsatile secretion, assay error, and biologic heterogeneity. Besides the expected day-to-day change in progesterone levels during the luteal phase, seven of ten women exhibited a significant circadian variation in progesterone; however, the time of day of the peak level was not consistent among women. Prolactin levels did not demonstrate any clinically relevant change over the menstrual cycle, but did have a consistent circadian pattern (nocturnal rise) over the 24-hour study period. Pulsatile variation occurred in both progesterone and PRL levels during the 24-hour admission. Five different reference ranges were generated from randomly selected single daily values from the 28 normal menstrual cycles. Although the mean levels calculated for each reference range were similar, the reference ranges demonstrated considerable variation due to the random sampling. In the five progesterone reference ranges, the lower limit of the range varied from 2.7-6.1 ng/mL, whereas the upper limit varied from 24.2-42.1 ng/mL.(ABSTRACT TRUNCATED AT 250 WORDS)