Outcome of triplet pregnancies after assisted reproductive techniques: how frequent are the vanishing embryos?

OBJECTIVE: To assess the incidence of spontaneous embryo reduction as well as the obstetric and neonatal outcome of triplet gestations after assisted reproductive techniques (ART).

METHODS: We analyzed the spontaneous outcome of 38 pregnancies in which three gestational sacs were identified with vaginal ultrasound between 21 and 28 days after ART. Weekly follow-up visits were scheduled during the first trimester until referral to a high-risk obstetrician. After delivery, each patient was interviewed individually and, if necessary, the obstetrician was contacted.

RESULTS: The triplets delivery rate was 47.4%, whereas 31.6% delivered twins, 18.4% delivered singletons, and only one patient miscarried all three cases (2.6%). Finding three fetal heart beats was associated with a triplet delivery rate of 69.2%, a twin incidence of 19.2%, and a singleton birth rate of 11.6%. Embryo resorptions were observed mainly during the first 7 weeks of gestation and did not occur beyond the 14th week. The mean gestational age at delivery and neonatal birth weight were significantly lower among triplets (32.8 weeks and 1,740 g versus 35.3 weeks and 2,352 g in twins and 39.1 weeks and 3,122 g for singletons). Triplets had a 100% prematurity and cesarean section rate compared with 67% and 75% in twins and 0% and 43% in singletons, respectively. Hospitalization at the Neonatal Intensive Care Unit was required in 83% of newborn triplets, 29% of twins, and 0% of singletons, with a mean stay of 34 and 21 days for triplets and twins, respectively. One stillbirth and no neonatal deaths were reported, with an overall perinatal mortality rate of 11.9 per 1,000.

CONCLUSIONS: Spontaneously, approximately 50% of triplet pregnancies will experience at least one embryo resorption. The ongoing triplets demand a complex and more expensive perinatal management, a strong argument to consider limiting the number of oocytes-embryos transferred in ART.