Gestational weight gain in twin gestations and pregnancy outcomes: a systematic review and meta‐analysis

Background Data on the association of inappropriate gestational weight gain (GWG) and adverse outcomes in twin pregnancies are limited and inconsistent. Objectives To perform a systematic review and meta‐analysis on the association between GWG and adverse outcomes in twin pregnancies. Search strategy Ovid, Medline, EMBASE and Cochrane Central databases from 1 January 1990 until 23 September 2020. Selection criteria Interventional and observational studies evaluating the association between GWG and adverse outcomes in twin pregnancies. Data collection and analysis Data were extracted by two independent reviewers. Summary odds ratios (OR) were calculated using a random‐effects model in a subset of studies that analysed GWG as a categorical variable in relation to the Institute of Medicine (IOM) recommendations. The primary outcome was preterm birth. Main results From 277 citations, 19 studies involving 36 023 women with twin pregnancies were included in the qualitative analysis, of which 14 were included in the meta‐analysis. Overall, 56.8% of women experienced inappropriate GWG: 35.4% (95% CI 30.0–41.0%) gained weight below and 21.4% (95% CI 14.2–29.5%) gained weight above IOM recommendations. Compared with GWG within IOM guidelines, GWG below IOM guidelines was associated with preterm birth before 32 weeks of gestation (OR 3.38; 95% CI 2.05–5.58), and a reduction in the risk of pre‐eclampsia (OR 0.68; 95% CI 0.48–0.97). GWG above IOM guidelines was associated with an increased risk of pre‐eclampsia that was consistent across all body mass index categories. Conclusions Inappropriate GWG affects over half of twin pregnancies, so is a common and potentially modifiable risk factor for preterm birth and pre‐eclampsia.