Influence of weight gain, according to Institute of Medicine 2009 recommendation, on spontaneous preterm delivery in twin pregnancies

Backgrounds: Maternal total weight gain during pregnancy influences adverse obstetric outcomes in singleton pregnancies. However, its impact in twin gestation is less understood. Our objective was to estimate the influence of total maternal weight gain on preterm delivery in twin pregnancies. Methods: We conducted a retrospective cohort study including diamniotic twin pregnancies with spontaneous labor delivered at 28 + 0 weeks or later. We analyzed the influence of total weight gain according to Institute of Medicine (IOM) cut-offs on the development of preterm delivery (both less than 34 and 37 weeks). Outcome were compared between under and normal weight gain and between over and normal weight gain separately using Fisher's exact test with Holm-Bonferroni correction. Results: One hundred seventy five women were included in the study and divided into three groups: under (52.0%), normal (41.7%) and overweight gain (6.3%). Normal weight gain was associated with a reduction in the rate of preterm delivery compared to under and over weight gain [less than 34 weeks: under vs. normal OR 4.97 (1.76-14.02), over vs. normal OR 4.53 (0.89-23.08); less than 37 weeks: OR 3.16 (1.66-6.04) and 6.51 (1.30-32.49), respectively]. Conclusions: Normal weight gain reduces spontaneous preterm delivery compared to over and underweight gain.