Now a common condition, obesity is estimated to affect up to one-third of American women of reproductive age. If you are overweight or obese and are concerned about how your size may impact your baby’s health, take heart — and be proactive in establishing good, consistent prenatal care. Working with your healthcare provider is essential, in order to optimize safety and ensure a healthy pregnancy and delivery for both you and your child.
FOR YOUR HEALTH
The measurement used to classify weight is the Body Mass Index (BMI), which is calculated using both height and weight. Measurements of BMI are divided into categories: normal weight (BMI 18.5 to 24.9 kg/m2), overweight (BMI 25 to 29.9 kg/m2) and obesity (BMI greater than 30 kg/m2). As an example, for the average woman in the U.S. who is 5’4″ tall, 108 to 145 pounds corresponds to a normal BMI, 146 to 174 pounds an overweight BMI, and greater than 174 pounds an obese BMI. You can calculate your own BMI online: http://www.nhlbi.nih.gov/
Your provider uses your BMI to help create a plan for prenatal care — which includes testing, ultrasounds, and establishing goals for nutrition and weight gain.
Since overweight and obese pregnant women may be at increased risk for complications that include diabetes (affecting 6 to 10 percent) and high blood pressure disorders (affecting 13 to 19 percent), your provider may recommend early or repeated diabetes testing, as well as other careful monitoring.
If you are diagnosed with gestational diabetes, you will need to have a special diet for diabetes, check blood sugar levels at home upon awakening and after meals, and use insulin if needed. Your provider will check blood pressure at every visit and review any worrisome symptoms, especially in the third trimester. If high blood pressure develops in pregnancy, treatment can range from simply increased monitoring to early delivery in severe cases. Finally, obese pregnant women are at increased risk of a Cesarean delivery for a variety of reasons, including the increased likelihood of needing a post-term induction of labor.
FOR YOUR BABY
Potential risks to the baby may include preterm delivery, high birth weight, post-term delivery, and a slightly increased risk of some birth defects. There is also a small increased risk for stillbirth, which may be related to high blood pressure and diabetes. For these reasons, obese women are recommended to undergo an ultrasound at 18 to 20 weeks (routine for all pregnancies), a blood test for spinal column defects (called AFP), as well as possible additional ultrasounds to check growth and fetal well-being in the third trimester.
Some studies have suggested that infants with a higher birth weight who are born to obese women have an increased risk of obesity later in life. However, this is an area requiring further research.
MANAGING YOUR WEIGHT
The established national guidelines for ideal weight gain in pregnancy are: 25 to 35 pounds for normal-weight women, 15 to 25 pounds for overweight women, and 11 to 20 pounds for obese women. A provider may advise a severely obese woman to gain less weight, but you should not skip meals during pregnancy. It’s important to remember to have a discussion with your provider in order to establish and help meet your individual goals.
A balanced diet is important for all pregnant women, and your provider may refer you to a nutritionist for guidance.
Your provider may recommend regular, moderate exercise (30 minutes on most days), but, again, you need to have a discussion so an exercise plan can be individualized for you.
Although obese women may be at higher risk for pregnancy complications, with careful attention to prenatal care, early testing for diabetes, and increased fetal monitoring when necessary, you and your provider can achieve a healthy pregnancy outcome.
Margaret K. Chory, MD, is a resident in obstetrics/gynecology at Beth Israel Deaconess Medical Center, Boston.