Weight optimisation strategies in pregnant obese women


Roughly one in five pregnant women are obese and this number is increasing. High maternal weight gain in pregnancy is associated with adverse maternal and foetal outcomes. These risks are increased in mothers who are already obese at booking. Strategies aiming to optimise maternal weight during pregnancy have been shown to be effective in reducing gestational weight gain and improving maternal health outcomes.

Guidelines on maternal weight gain during pregnancy

In 2009 the US Institute of Medicine (IoM) set out guidelines advising the optimal weight gain during singleton pregnancies. The primary goal of this strategy was to increase the proportion of babies born with a birth weight of between 3000 and 4000 g. This guidance also takes into account the long-term maternal and child health consequences of weight gain in pregnancy. FIGO advises that ‘pregnant women with a BMI ≥30 should be advised to avoid high gestational weight gain. Weight gain should be limited to 5–9 kg’ ( Table 23.1 ).

Table 23.1
IOM guidance 2009 about total weight gain and rates of weigh gain during pregnancy.
Prepregnancy weight status (body mass index category) Recommended total weight gain ranges Recommended rates of weight gain in the second and third trimester *
Pounds Kilograms Pounds/week Kilograms/week
Underweight (<18.5 kg/m 2 ) 28–40 12.5–18 1.0 (1.0–1.3) 0.51 (0.44–0.58)
Normal (18.5–24.9 kg/m 2 ) 25–35 11.5–16 1.0 (0.8–1.0) 0.42 (0.35–0.50)
Overweight (25–29.9 kg/m 2 ) 15–25 7–11.5 0.6 (0.5–0.7) 0.28 (0.23–0.33)
Obese (>30 kg/m 2 ) 11–20 5–9 0.5 (0.4–0.6) 0.22 (0.17–0.27)

* Calculations assume a 0.5-2 kg (1.1-4.4 lbs) weight gain in the first trimester.

Antenatal consequences of increased gestational weight gain

  • 1.

    Increased risk of developing gestational hypertension/preeclampsia

  • 2.

    Increased risk of developing gestational diabetes

  • 3.

    Increased risk of complications in labour and delivery:

    • a.

      Increased risk of induction of labour and failure of induction labour

    • b.

      Prolonged duration of labour

    • c.

      Increased risk of caesarean section.

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