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Objective: Little information exists related to the contribution of assisted reproductive technology (ART) twins to the preterm and very preterm birth rate. We sought to examine this contribution over a period of more than two decades in a tertiary perinatal center. Methods: We identified all preterm births from 1993 to 2017, born at <37 or <32 weeks' gestation, by mode of conception [in vitro fertilization (IVF) vs. non-IVF pregnancies]. We generated trend lines of the annual change of the dependent variable (% preterm birth). Results: We evaluated 74,299 births, including 3934 (5.3%) preterm births at <37 and 826 (1.1%) at <32 weeks' gestation. In this period, 1019 (1.4%) twin pairs were born including 475 (46.6%) and 80 (7.8%) at <37 and <32 weeks, respectively. There were 213 (5.4%) IVF pregnancies among the preterm births at <37 weeks, including 88 (41.3%) twins. Fifteen (1.8%) births of all IVF gestations were at <32 weeks, and all were twins. Whereas the annual rate of spontaneous twins did not change, a significant increase over time exists for IVF twins (P < 0.05, R2 = 0.6). We demonstrated an increase in IVF twin births at <37 weeks but not for spontaneously conceived twins. Whereas the twin birth rate at <32 weeks did not change over time, all preterm births at <32 weeks following IVF were twins. Conclusion: The risk of twins after ART increasingly contributes to preterm births at <37 weeks and ART twins are at significant risk for preterm births at <32 weeks. [ABSTRACT FROM AUTHOR]

Objective: To assess the effect of fetal gender in small-for-gestational age (SGA) neonates with birth weight less than the fifth percentile by gestational age. Methods: We compared male and female SGA neonates for maternal and neonatal outcomes in the following gestational age subgroups: at <32 + 6, 33 + 0–36 + 6 and at ≥37 + 0 weeks of gestation. Results: We examined 159, 154 and 2363 SGA neonates born at <32 + 6, 33 + 0 to 36 + 6 and ≥37 weeks of pregnancy, respectively, whose birth weight was below the fifth percentile for gestational age and who met our inclusion criteria. Overall, there were no significant differences between the mothers of males and females, except that there were more males at term and the incidence of nulliparas was greater among the mothers of males. In terms of outcomes, males had a similar incidence of respiratory distress syndrome (RDS), intraventricular hemorrhage (IVH) and admissions to intensive care. Interestingly, low Apgar scores were more common in preterm females born at 33–37 weeks and vice versa in births over 37 weeks. Conclusion: Our data do not support an advantage of either gender in preterm birth of infants who are most likely growth restricted. [ABSTRACT FROM AUTHOR]