Mode of conception, placental morphology and perinatal outcome of twin gestations.

Objective: To compare the perinatal outcome and placental morphology of twins conceived by assisted reproductive technologies (ART) or natural conception (NC).

Methods: The present retrospective study included 88 twin pairs. Methods of ART included in vitro fertilization, intrauterine insemination, embryo transfer and induced ovulation. Placental morphology was described by chorionicity, amnionicity, placental weight, umbilical cord insertion and the number of cord vessels. Perinatal outcomes included maternal age, gestational age, birth weight (BW), BW discordance and mode of delivery.

Results: The mothers of ART twins were 4 years older than NC mothers. ART twins delivered 2.2 weeks earlier than NC twins. The BW of ART twins A and B were less than NC twins A and B. There was no difference in the proportion of discordant twins in either group. Dichorionic diamniotic (DD) placentas accounted for the majority of placentas in both groups. There were no monochorionic-monoamniotic placentas in ART pairs, but there were 2.9% in NC pairs. Mode of conception had no effect on placental weight in DD or monochorionic-diamniotic twins in either group except for larger DD fused placentas in the ART group.

Conclusion: ART twin pairs were delivered at an earlier gestational age at lower birth weights to older mothers predominantly by cesarean section. This perinatal outcome was not reflected by placental morphology.