A high BMI, or body mass index, is associated with increased risk of pregnancy complications, including fetal death. It is not always possible to reach your ideal weight before pregnancy. Whatever your starting weight, you can manage your weight gain and avoid complications from obesity during pregnancy by working closely with your physician before you get pregnant and during your pregnancy.
Significance
Numerous research studies have examined pre-pregnancy BMI and pregnancy outcomes. BMI is a measure of body weight in relation to height. BMI ranges are often used to designate underweight (BMI less than 20), normal weight (20 to 24.9), overweight (25 and 29.9), obese (30 to 34.9) and morbidly obese (35).
Effects
One of the larger studies looking at the effects of pre-pregnancy BMI on pregnancy outcomes was published by Sohinee Bhattacharya, Doris Campbell, William Liston and Siladitya Bhattacharya in the journal BMC Public Health. The doctors analyzed 30 years of pregnancy datafrom the Aberdeen Maternity and Neonatal Databank to determine if women in various BMI categories before pregnancy had different risks for pregnancy complications such as pre-eclampsia, induced labor, C-section, post-partum hemorrhage and pre-term delivery. The study found that women with abnormally high BMIs before pregnancy were more likely to experience pre-eclampsia, high blood pressure, abnormally large babies, labor induction and risky C-section deliveries. In contrast, underweight women had better pregnancy outcomes that normal weight women.
Warning
The March of Dimes information sheet "Maternal Obesity and Pregnancy:Weight Matters" warns that maternal obesity before pregnancy can increase the risks of birth defects, especially neural tube defects, as well as increase the risk of fetal death or still birth. In women of reproductive age, 2003 data compiled by the March of Dimes estimated that almost 20 percent were obese with a BMI over 30. March of Dimes recommendations for weight gain vary depending on the patient's pre-pregnancy weight. For example, underweight women should attempt to gain 28 to 40 lbs. during pregnancy, while obese women should limit their weight gain to 15 lbs.
Expert Insight
The American Dietetic Association and American Society for Nutrition have issued a position paper on obesity, reproduction and pregnancy outcomes. Obese women who used bariatric surgery to reduce obesity before pregnancy reported pregnancy complications including poor intestinal absorption of some nutrients, increased vomiting, and suboptimal weight gain, which can cause problems for the growing fetus. Women are encouraged to delay conception for one year after bariatric surgery to fully recover from the surgery, adjust to restricted caloric intake and reach a stable body weight.
Prevention
Prevention of adverse pregnancy outcomes from high BMI means working closely with your physician before and during pregnancy. If you are planning to get pregnant and are overweight, talk to your physician about reaching your ideal pre-pregnancy weight. Work toward reaching your ideal weight by following a sensible weight loss plan including increasing daily exercise and eating a healthy diet. Avoid fad diets that promise rapid weight loss. Even if you don't reach your ideal weight before getting pregnant, you can prevent or manage pregnancy complications that may occur. Talk to your physician about how much weight you should gain during pregnancy. Ask your physician about safe levels of exercise in pregnancy, healthy eating habits and the use of prenatal vitamins to supplement a healthy diet.
References
- Biomed Central: "Effect of Body Mass Index on pregnancy outcomes in nulliparous women delivering singleton babies;" 2007
- March of Dimes: Maternal Obesity and Pregnancy Weight Matters
- Nutrition.org: Position of the American Dietetic Association and American Society for Nutrition: Obesity, Reproduction, and Pregnancy Outcomes
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