Low gestational weight gain and the risk of preterm birth and low birthweight: a systematic review and meta-analyses

Background. Low gestational weight gain is common, with potential adverse perinatal outcomes. Objective. To determine the relation between low gestational weight gain and preterm birth and low birthweight in singletons in developing and developed countries. Data sources. Medline, EMBASE and reference lists were searched, identifying 6 283 titles and abstracts. Methods of study selection. Following the MOOSE consensus statement, two assessors independently reviewed titles, abstracts, full articles, extracted data and assessed quality. Results. Fifty-five studies, 37 cohort and 18 case-control, were included, involving 3 467 638 women. In the cohort studies (crude data, generally supported where available by adjusted data and case-control studies), women with low total gestational weight gain had increases in preterm birth < 37 weeks [RR 1.64 (95% CI 1.62-1.65)], 32-36 weeks [RR 1.39 (95% CI 1.38-1.40)] and <= 32 weeks [RR 3.80 (95% CI 3.72-3.88)]. Low total gestational weight gain was associated with increased risks of low birthweight < 2 500 g [RR 1.85 (95% CI 1.72-2.00)], in developing and developed countries [RR 1.84 (95% CI 1.71-1.99) and RR 3.02 (95% CI 1.37-6.63), respectively], 1 500-2 500 g [RR 2.02 (95% CI 1.88-2.17)] and < 1 500 g (RR 2.00 (95% CI 1.67-2.40)]. Women with low weekly gestational weight gain were at increased risk of preterm birth [RR 1.56 (95% CI 1.26-1.94)], 32-36 weeks [RR 2.43 (95% CI 2.37-2.50)] and <= 32 weeks [RR 2.31 (95% CI 2.20-2.42)] but not low birthweight [RR 1.64 (95% CI 0.89-3.02)]. Conclusions. In this systematic review, we determined that singletons born to women with low total gestational weight gain have higher risks of preterm birth and low birthweight, with the lower the gain, the higher the risks.