Bumps and Beyond


Research has shown that excessive weight gain in pregnant women with a body mass index (BMI) above 30 has been linked to several risks and complications. The higher a woman’s BMI, the higher the risks.


These risks include:

  • Miscarriage – the overall risk of miscarriage under 12 weeks is one in five (20%); if you have a BMI over 30, the risk is one in four (25%)
  • Gestational diabetes – if your BMI is 30 or above, you are three times more likely to develop gestational diabetes than women whose BMI is below 30
  • High blood pressure and pre-eclampsia– if you have a BMI of 35 or above at the beginning of your pregnancy, your risk of pre-eclampsia is twice that of women who have a BMI under 25
  • Blood clots – all pregnant women have a higher risk of blood clots compared to women who are not pregnant, and if your BMI is 30 or more the risk is additionally increased
  • Shoulder dystocia – the baby’s shoulder becoming “stuck” and difficult to deliver during labour
  • Heavier bleeding than normal after the birth and more chance of infection in wounds
  • Having a baby weighing more than 4kg (8lb 14oz) – the overall risk of this for women with a BMI between 20 and 30 is 7 in 100 (7%); if your BMI is over 30, your risk is doubled to 14 in 100 (14%)
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