The association between gestational weight gain and perinatal outcomes among underweight women with twin pregnancy in Japan

Objective To clarify the association between gestational weight gain (GWG) and pregnancy outcomes in underweight women with twin pregnancies in Japan. Methods This retrospective study derived data from the Japan Society of Obstetrics and Gynecology perinatal database between 2007 and 2015. We included 5049 underweight (pre-pregnancy body mass index [BMI] <18.5 kg/m(2)) and 20 812 (BMI >= 18.5 and <25 kg/m(2)) normal-weight, twin-pregnant women. Weekly GWG was stratified into 10 categories. Logistic regression was used to assess the effects of GWG on pregnancy. The primary outcomes evaluated were small-for-gestational age (SGA), preterm birth, preeclampsia, and cesarean delivery. Results In underweight group, high GWG was associated with significant risk reductions in both twins being SGA, at least one twin being SGA, very preterm birth, and extreme preterm birth, while a risk increase was observed in preeclampsia. Compared to women with GWG of 0.25-0.30 kg/week, the risk of preeclampsia was significantly higher in women with GWG >0.35 kg/week. No association was observed between GWG and cesarean delivery. These associations were similar in the normal-weight group. Conclusion Underweight women with twin pregnancies showed an inverse association between GWG and SGA or preterm birth. The risk of preeclampsia was higher in women who gained >0.35 kg/week.

Automated summary

This study aimed to investigate the association between gestational weight gain (GWG) and pregnancy outcomes in underweight women with twin pregnancies in Japan. The study found that high GWG was associated with a reduced risk of both twins being small-for-gestational age (SGA) and preterm birth, as well as an increased risk of preeclampsia. The risk of preeclampsia was significantly higher in women who gained more than 0.35 kg/week. There was no association between GWG and cesarean delivery. These findings were consistent with those observed in normal-weight women with twin pregnancies.