Comparison of pregnancy outcomes based on chorionicity between spontaneous and in vitro fertilization twins

Nam, Soo Hyun; Lee, Ji Eun; Moon, Seong O; Choi, Suk Joo; Kim, Hyung Sun; Oh, Soo Young; Kim, Jong Hwa; Roh, Cheong Rae

Abstract

OBJECTIVE
To compare the pregnancy outcomes of in vitro fertilization (IVF) twins with those of spontaneous twins based on their chorionicities.
METHODS
We performed a retrospective analysis of 598 twin pregnancies beyond 24 weeks of gestation delivered from October 1994 to December 2003. Subjects were grouped into the spontaneous group (n=392) and the IVF group (n=206) and then subgrouped into dichorionic (n=193, spontaneous vs. n=156, IVF) and monochorionic (n=154, spontaneous vs. n=34, IVF) subgroups. First, the obstetric and perinatal outcomes were compared between the spontaneous group and the IVF group regardless of their chorionicity. Second, the same outcome variables were compared between the spontaneous and the IVF group with same chorionicity.
RESULTS
There was a significant increase in the incidence of preterm deliveries before 37 weeks of gestation in IVF twins (74.5% spontaneous vs. 82.5% IVF, p=0.031). However, the gestational age at delivery was not significantly different (34.5+/-2.86 weeks vs. 34.2+/-0.28 weeks). Antepartum admission was also significantly increased in IVF group (4.6% vs. 9.2%, p<0.001). We were unable to observe any significant difference in perinatal outcomes between the two groups other than increased in utero fetal demise in utero in the IVF group (0.3% vs. 1.5%, p<0.05). When we reanalyzed pregnancy outcomes based on chorionicity, there were more frequent admission to neonatal intensive care unit (42.7% vs. 52.6%, p<0.05) and necrotizing enterocolitis (0.5% vs. 3.5%, p<0.05) in dichorionic twins of the IVF group. In monochorionic twins, the incidence of placenta previa was increased in the IVF twin group (0% vs. 11.8%, p<0.001).
CONCLUSION
In the IVF twins, the incidence of placenta previa was increased in monochrionic twins and the incidence of neonatal intensive care unit admission and necrotizing enterocolitis were also increased in dichorionic twins.