Monday, October 8, 2007

Pregnancy weight gain - one size doesn't fit all

Most women know about the traditional weight gain recommendations for pregnancy: 25-35 pounds if you're normal weight (body mass index = 20-25), up to 10 pounds more if you started the pregnancy underweight (BMI <> 25). However, a new study published this week in Obstetrics & Gynecology suggests that these guidelines may be out of date, at least as far as obese women are concerned.

Investigators analyzed data from more than 120,000 obese women in Missouri to see how the weight they gained during pregnancy affected three outcomes: blood pressure, rate of cesarean sections, and the infant's birth weight. They found that 23% of obese women gained less than 15 pounds, 31% gained the recommended 15-25 pounds, and nearly 50% gained more than 25 pounds. The women who gained less weight during pregnancy had the best outcomes, including less pregnancy-induced high blood pressure and normal weight babies.

The researchers also calculated optimal ranges of weight gain during pregnancy based on pre-pregnancy BMI. Women with BMIs of 30-34.9 had the best outcomes when they gained between 10 and 25 pounds. These same women were more likely to have low birth-weight babies when they lost weight, but they had fewer other complications like high blood pressure and C-section deliveries. Women with a BMI of 35-39.9 did best when they gained less than 9 pounds. For women with a BMI of 40 or higher, losing up to 9 pounds produced the best outcomes.

As you can see, this study's findings contradict the current guidelines, which were established in 1990 when obesity wasn't so common. However the current guidelines may be no more. The Institute of Medicine plans to reevaluate its recommendations for weight gain during pregnancy to reflect more recent evidence about pregnancy and birth outcomes.

What does this mean for you? If you are obese and pregnant, or planning to become pregnant, talk to your doctor or midwife about the best weight gain - or weight loss - strategy. And remember, no matter what weight you are, it's important to eat a nutritious and well-rounded diet while pregnant and postpartum.

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