Maternal obesity, preterm birth, and low birth weight

January 01, 0001

Maternal obesity, preterm birth, and low birth weight

These Canadian and Chinese researchers examined the relation between maternal obesity and preterm birth and low birth weight. They performed a systematic review and meta-analyses utilizing Medline and Embase, and reference lists of identified articles.

The researchers found: "84 studies (64 cohort and 20 case-control) were included, totalling 1 095 834 women. Although the overall risk of preterm birth was similar in overweight and obese women and women of normal weight, the risk of induced preterm birth was increased in overweight and obese women (relative risk 1.30). Although overall the risk of having an infant of low birth weight was decreased in overweight and obese women (0.84), the decrease was greater in developing countries than in developed countries (0.58 v 0.90). After accounting for publication bias, the apparent protective effect of overweight and obesity on low birth weight disappeared with the addition of imputed "missing" studies (0.95), whereas the risk of preterm birth appeared significantly higher in overweight and obese women (1.24)."

The researchers concluded: "Overweight and obese women have increased risks of preterm birth and induced preterm birth and, after accounting for publication bias, appeared to have increased risks of preterm birth overall. The beneficial effects of maternal overweight and obesity on low birth weight were greater in developing countries and disappeared after accounting for publication bias."

This systematic review and meta-analysis finds obese and overweight pregnant patients at increased risk of preterm birth and did not find evidence of a protective effect on low birth weight.


For the full abstract, click here.

BMJ 341:c3428, 20 July 2010 © 2010 McDonald et al.
Overweight and obesity in mothers and risk of preterm birth and low birth weight infants: systematic review and meta-analyses. Sarah D McDonald, Zhen Han, Sohail Mulla, Joseph Beyene, on behalf of the Knowledge Synthesis Group. Correspondence to S D McDonald: [email protected]

Category: W. Pregnancy, Family Planning. Keywords: obesity, overweight, pregnancy, preterm birth, low birth weight, systematic review and meta-analysis of observational studies, journal watch.
Synopsis edited by Dr Paul Schaefer, Toledo, Ohio. Posted on Global Family Doctor 3 August 2010

Pearls are an independent product of the Cochrane primary care group and are meant for educational use and not to guide clinical care.

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