High gestational weight gain and the risk of preterm birth and low birth weight: a systematic review and meta-analysis.

OBJECTIVE: Many women have high gestational weight gain (GWG), but potential neonatal consequences are not yet well quantified. We sought to determine the relationship between high GWG and preterm birth (PTB) and low birth weight (LBW) in singleton births.

DATA SOURCES: We searched Medline and Embase and reference lists.

STUDY SELECTION: Two assessors independently performed all steps. We selected studies assessing high total or weekly GWG on PTB (< 37 weeks) and LBW (< 2500 grams).

DATA EXTRACTION AND SYNTHESIS: Thirty-eight studies, 24 cohort and 14 case-control, were included involving 2 124 907 women. Most contained unadjusted data. Women with high total GWG had a decreased risk overall of PTB < 37 weeks (relative risk [RR] 0.75; 95% CI 0.60 to 0.96), PTB 32 to 36 weeks (RR 0.70; 95% CI 0.70 to 0.71), and < 32 weeks (RR 0.87; 95% CI 0.85 to 0.90). High GWG was associated with lower risk of LBW (RR 0.64; 95% CI 0.53 to 0.78). Women with the highest GWG had lower risks of LBW (RR 0.55; 95% CI 0.32 to 0.94) than women with moderately high GWG (RR 0.73; 95% CI 0.60 to 0.89). Women with the highest weekly GWG had greater risks of PTB (RR 1.51; 95% CI 1.47 to 1.55) than women with moderately high weekly GWG (RR 1.09; 95% CI 1.05 to 1.13). Women with high weekly GWG were at increased risk of PTB 32 to 36 weeks (RR 1.14; 95% CI 1.10 to 1.17 and < 32 weeks (RR 1.81; 95% CI 1.73 to 1.90).

CONCLUSION: Although women with high total GWG have lower unadjusted risks of PTB and LBW, high weekly GWG is associated with increased PTB, and more adjusted studies are needed, as are more studies in obese women. Potential benefits of high GWG for the infant must be balanced against maternal risks and other known infant risks such as high birth weight.