Practice Pregnancy Plus

Obesity and pregnancy

BMJ 2008; 337 doi: (Published 15 December 2008) Cite this as: BMJ 2008;337:a2450
  1. Naomi E Stotland, assistant professor
  1. 1Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California San Francisco, 1001 Potrero Avenue 6D-1, San Francisco CA 94110, USA
  1. Correspondence to: N E Stotland stotlandn{at}

    This article explores the increased risks of obesity in pregnancy and suggests strategies to minimise them

    Over one billion adults worldwide are estimated to be overweight, with 400 million of these classed as obese.1 About half of women of reproductive age in the United States are either overweight or obese.2

    How does obesity affect pregnancy and pregnancy outcomes?

    Obesity affects reproduction in women in many ways (see scenario box for an example). Table 1 lists the complications associated with obesity in pregnancy. Although most obese women will have a good overall obstetric outcome, obesity was a major predictor of maternal mortality and major complications in a recent study.3


    A 25 year old woman, in her second pregnancy, presents for prenatal care in the first trimester of pregnancy. She is 1.57 m (5 ft 2 in) and weighs 82 kg (12 stone 13 lb) at nine weeks’ gestation. She is unsure of her preconception weight. Her obstetric history is notable for an urgent caesarean delivery of a 4200 g infant after labour was induced for pre-eclampsia at 38 weeks’ gestation. That pregnancy was complicated by excessive weight gain (18 kg).

    View this table:
    Table 1

     Pregnancy complications associated with obesity

    How does pregnancy affect body habitus in obese women?

    Although the absolute amount of weight gained by obese women tends to be less than the amount gained by women of normal weight, overweight and obese women have higher rates of excessive weight gain, according to the Institute of Medicine’s guidelines (table 2), which vary by prepregnancy body mass index (weight (kg)/(height (m)2).4 In one population based cohort study in the US, 46% of obese women gained more than 25 lbs (11.3 kg).5 In the US, women with a high body mass index before pregnancy are also more likely to retain the weight they gained in pregnancy long term.6

    View this table:
    Table 2

      US Institute of Medicine’s …

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