119: Nulliparity, art and twins: A time for re-thinking

During the last decades, mainly due to assisted reproductive techniques (ART) we are facing an increase in the rate of twin pregnancy. Twin pregnancies are well established high risk pregnancies, carrying a substantial medical and economical burden; the most substantial factors are clearly prematurity and low birth weight. Our goal was to evaluate the risk that nulliparity poses to the outcome of twin pregnancies. We prospectively enrolled into the study a cohort of twin pregnancies achieved following ART, after completing the first trimester. The patients were treated in a single outpatient fertility center between 1/1/2004 and 31/07/2008. Pregnancies achieved by egg donation were excluded. Outcome measures were: second trimester abortion, length of hospitalization during the pregnancy, gestational age at delivery, birth weight and the number of liveborns The results of 244 twin pregnancies (2/3 nulliparas) were available for evaluation. Second trimester miscarriage rate was 9.3% in nulliparas and only 2.4% in multiparas (P value= 0.061). Gestational age at the day of delivery was more advanced in multiparas with a significant difference in the proportion of deliveries occurring at or prior to 32 weeks: 15.1% in nulliparas as compared to 2.5% in multiparas (P value=0.03). Better outcome of multiparas was also demonstrated by the calculated chance of taking home at least one baby in a twin pregnancy: 97.6% for multiparas as compared to only 89.2% in nulliparas (P value 0.024). Using a multivariate logistic regression analysis and adjustment for age, treatment modality and fetal reduction procedure, parity remained the only contributing variable. Nulliparity is a risk factor for a poor outcome in twin pregnancies, associated with an increased risk for both second trimester abortions and a significant prematurity. This information should be discussed with the couple as part of the decision process related to the number of embryos to be transferred.