Observational study of associations between gestational weight gain and perinatal outcomes in dichorionic twin pregnancies

Objective: To evaluate relationships between gestational weight gain (GWG) and adverse events during pregnancy among patients of normal weight with twin pregnancies. Methods: The present observational study included patients with dichorionic twin pregnancies with a pre-gravid body mass index of 18.5-24.99 kg/m(2) who underwent delivery at no earlier than 22 weeks of pregnancy between January 1, 2007, and June 30, 2016, at the Medical University of Warsaw, Warsaw, Poland. The GWG ratio was categorized as low (< 0.45 kg/wk), adequate (0.45-0.66 kg/wk), or high (> 0.66 kg/wk), and pregnancy outcomes were compared between the GWG ratio groups. Associations between GWG ratio and pregnancy outcomes were estimated using generalized additive models. Results: There were 201 patients included in the study. No differences in rates of preterm delivery, very preterm delivery (VPTD), small for gestational age fetus, pre-eclampsia, gestational diabetes, preterm premature rupture of membranes, or intrauterine fetal demise were observed between the patient groups. Linear relationships with GWG ratio were recorded for VPTD (P=0.019) and spontaneous VPTD (P=0.003); non-linear relationships with GWG ratio were recorded for pre-eclampsia (P=0.023) and perinatal mortality (P=0.015). A GWG ratio of 0.55-0.56 kg/wk appeared optimal in terms of twin pregnancy outcomes. Conclusion: The incidence of VPTD, pre-eclampsia, and perinatal mortality during dichorionic twin pregnancy were associated with GWG ratio.