Obstetric Outcome of Twin Pregnancies After In-Vitro Fertilization: A Matched Control Study in Four Dutch University Hospitals

Abstract

Higher-than-expected rates of obstetrical and perinatal complications are described in singleton pregnancies after in vitro fertilization (IVF), but studies comparing IVF and spontaneously conceived twins have given mixed results. This study contrasted 96 IVF twin pregnancies with the same number of control twin pregnancies closely matched for numerous factors: maternal age, parity, race, body size, smoking status, hospital, delivery date, and obstetrical and medical histories. Women who had received IVF were 6 months older on average. Just over two-thirds of both groups were primiparas. Vaginal bleeding was more frequent in IVF pregnancies (32% vs. 19%), with most episodes occurring during the first trimester. There were no significant group differences in gestational diabetes, placenta previa, or preterm membrane rupture. Rates of spontaneous labor, induction, and elective cesarean delivery also were comparable in the two groups. Newborn infants were in similar condition at birth. Both first- and second-born infants weighed less in the IVF group, but the differences were not statistically significant. In all, 61% of IVF infants and 44% of control infants had low birthweight, and about one-fourth of the infants in each group were small for gestational age. Birthweight discordance averaged 17.6% for IVF twins and 14.3% for control twins, and discordance exceeding 25% was more frequent in the IVF group (22.9% vs. 11.5%). Fewer than 4% of infants in each group had congenital malformations. The average number of days in neonatal care was 12.4 for IVF infants and 10.7 for control infants, also not a significant difference, and no particular neonatal problems were significantly more prevalent in IVF children. These findings affirm that, in some respects, the outcomes of IVF twin pregnancies differ from those of naturally conceived twin pregnancies.