This sheet talks about maternal obesity in pregnancy and while breastfeeding. This information should not take the place of medical care and advice from your healthcare provider.

What is obesity?

Obesity is a condition that is associated with too much body fat. More than one-third of women in the United States have weights that fall in the obesity range. One measure of obesity is body-mass index (BMI) which is an estimate of body fat based on height and weight. A person is said to be obese when their BMI is 30 or higher. For someone who is 5 foot 6 inches tall, a healthy non-pregnant weight range is 115 to 154 pounds. This same person is considered obese at 186 or more pounds. You can find your healthy weight range at https://www.cdc.gov/healthyweight/assessing/bmi/adult_bmi/english_bmi_calculator/bmi_calculator.html.

What about weight gain during pregnancy?

Weight gain during pregnancy is expected. The ideal amount of weight gain during pregnancy will vary with your pre-pregnancy BMI and the number of babies that you are carrying. Women who are overweight or obese may be encouraged to limit weight gain during pregnancy. In general, a total weight gain of 15–25 pounds for overweight women (BMI=25–29.9) and 11–20 pounds for obese women (BMI ≥ 30) is recommended. Please work closely with your healthcare providers to determine how much weight you should gain during pregnancy.

Can obesity during pregnancy cause miscarriage or birth defects?

Miscarriage can occur in any pregnancy, and in every pregnancy, a woman starts out with a 3-5% chance of having a baby with a birth defect. This is called her background risk.

Maternal obesity has been associated with a higher chance for miscarriage and with a higher chance for certain birth defects, such as problems with the heart and spine. However, the overall increased risk for miscarriage and/or birth defects is likely to be small. For example, about 1-2 babies of every 1,000 born will have a neural tube defect, which occurs when the spine or skull does not close properly. Obesity may double that risk, meaning that the actual increased risk is still small at 2-4 babies out of 1,000 babies born.

Ultrasounds (sound wave pictures of the baby) are used to screen a pregnancy for birth defects. However, obesity can make it harder for birth defects to be detected by ultrasound.

Can obesity cause pregnancy complications?

Obesity has been found to increase the chance for gestational diabetes and high blood pressure during pregnancy. Obesity might also cause an increased chance of premature delivery (babies born before 37 weeks of pregnancy) and stillbirth. Also, babies of mothers with obesity are at an increased chance for large body size (macrosomia) which can make delivery more complicated and increases the chance for obesity in childhood and as an adult. Obesity has also been associated with a greater chance for a cesarean section (c-delivery).

Can my obesity during pregnancy cause problems with learning in my child?

Some studies have suggested a possible association with learning difficulties in children born to obese

mothers. However, this is difficult to study so this in not clearly known.

Should I try to lose weight while pregnant?

Weight loss is generally not recommended during pregnancy. Ideally, weight loss should be done prior to pregnancy. If you are already pregnant and overweight or obese, limiting your weight gain might be recommended. Talk with your healthcare provider about your recommended weight gain, nutrition and exercise.

What about having maternal obesity while breastfeeding?

Maternal obesity is not considered a reason for concern with breastfeeding. Be sure to talk to your health care provider about all of your breastfeeding questions.

Is it safe for the father of the baby to be obese?

Studies have found that obesity in men can reduce fertility (make it harder for them to get a partner pregnant). In general, exposures that the fathers have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures and Pregnancy at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/pdf/.

Were can I find some more information?

The American College of Obstetricians and Gynecologists (ACOG) has a fact sheet with frequently asked questions about obesity and pregnancy: https://www.acog.org/Patients/FAQs/Obesity-and-Pregnancy.

Selected References:

  • American College of Obstetricians and Gynecologists. 2015. ACOG Committee opinion no. 156: Obesity in pregnancy. Obstet Gynecol. 126(6):e112-e126. Reaffirmed 2018.
  • American College of Obstetricians and Gynecologists. 2013. ACOG Committee opinion no. 548: Weight Gain During Pregnancy. Available at: https://www.acog.org/-/media/Committee-Opinions/Committee-on-Obstetric-Practice/co548.pdf?dmc=1&ts=20180102T2046334047
  • Cai GJ, et al. 2014. Association between maternal body mass index and congenital heart defects in offspring: a systematic review. Am J Obstet Gynecol. 211(2):91-117.
  • Catalano PM and Shankar K 2017. Obesity and pregnancy: mechanisms of short term and long term adverse consequences for mother and child. BMJ 356:j1.
  • Gilboa SM, et al. 2010. Association between prepregnancy body mass index and congenital heart defects. Am J Obstet Gynecol 202:51.e1-10.
  • Huang l, et al. 2014. Maternal prepregnancy obesity and child neurodevelopment in the Collaborative Perinatal Project. Int. J Epidemiol. 43(3):783-92.
  • Johnson J, et al. 2013. Eunice Kennedy Shriver National Institute of Child Health; Human Development (NICHD) Maternal-Fetal Medicine Units (MFMU) Network. Pregnancy outcomes with weight gain above or below the 2009 Institute of Medicine guidelines. Obstet Gynecol. 121(5):969-75.
  • Persson M, et al. 2017. Risk of major congenital malformations in relation to maternal overweight and obesity severity: cohort study of 1.2 million singletons. BMJ 357:j2563.
  • Stothard KJ,et al. 2009. Maternal overweight and obesity and the risk of congenital anomalies: a systematic review and meta-analysis. JAMA. 11;301(6):636-50.
  • Stubert J, et al. 2018. The risks associated with obesity in pregnancy. Dtsch Arztebl Int 115(16):276-283.
  • Tanda L, et al. 2013. The impact of prepregnancy obesity on children’s cognitive test scores. Matern Child Health J. 17:222-229.