Impact of monozygotic twinning on multiple births resulting from in vitro fertilization in the United States, 2006-2010.

OBJECTIVE: To determine the contribution of monozygotic twining to in vitro fertilization multiple births. STUDY DESIGN: We performed a retrospective analysis of the incidence of monozygotic twining in multiple births resulting from fresh embryo transfers using 2006-2010 data from the Society for Reproductive Technology Clinic Outcome Reporting System. RESULTS: The number of embryos transferred were fewer than the number of births in 0.5% (223/40950) of twin, 29% (659/2289) of triplet, and 64% (43/67) of quadruplet births resulting from transfer of fresh embryos from 2006 to 2010. In 2010, 37% of triplets and 100% of quadruplet births occurred when fewer than 3 and fewer than 4 embryos respectively were transferred. CONCLUSION: Monozygotic twinning plays a key role in the development of triplet and quadruplet pregnancies achieved through in vitro fertilization.

Histologic differences in placentas of preeclamptic/eclamptic gestations by birthweight, placental weight, and time of onset.

With preeclampsia/eclampsia (PE/E), infants more often are either large or small for gestational age. We explored whether the differences in infant birthweight (BW), placental weights (PW), or time of onset are associated with histologic features of maternal vascular underperfusion. A retrospective chart identified 243 PE/E gestations between 2007 and 2010. Gestational age only was known at slide review. Investigated features included increased syncytial knots, villous agglutination, increased intervillous fibrin, distal villous hypoplasia, acute atherosis, mural hypertrophy of membrane arterioles, muscularized basal plate arteries, increased placental site giant cells, increased immature intermediate trophoblasts, infarcts, and villitis. The results were correlated with BW, PW, and onset time PE/E. One hundred thirty-eight PE/E gestations were identified with adequate slides and history. Increased BW placentas had decreased syncytial knots and increased mural hypertrophy of membrane arterioles. Decreased BW had increased placenta site giant cells. Increased PW had decreased distal villous hypoplasia. Decreased PW had increased syncytial knots, increased intervillous fibrin, and increased acute atherosis. Early-onset disease had increased syncytial knots, distal villous hypoplasia, villous agglutination, and infarcts. This suggests PE/E is not a single process resulting in a uniform distribution of lesions but, rather, is composed of several different processes manifesting a single clinical presentation.