Size Matters | Fit Pregnancy

Size Matters

What you need to know about your baby's birth weight.

baby sitting on a scale
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Rare is the woman who wants her child to be average or unremarkable, but when it comes to birth weight, average and unremarkable earn an A-plus.

The vast majority of full-term babies (about 83 percent in the year 2000) weigh in between 5.5 and 8.8 pounds—the range that experts agree is normal and healthy for most newborns. Nevertheless, many women—including those who do everything possible to be healthy—worry about how much their babies will weigh. Of concern are the 7 percent of U.S. babies who weigh less than 5.5 pounds and are more likely to have immediate and long-term health problems, such as learning disabilities.

If an underweight woman does not gain enough weight during pregnancy, she may deliver a growth-restricted baby, says Rebecca Shiffman, M.D., director of obstetrics and vice chairwoman of the obstetrics/gynecology department at Methodist Hospital in New York and a medical adviser to the March of Dimes. A woman who was obese before pregnancy risks developing gestational diabetes and delivering a baby that is too heavy, and heavy babies are at risk for future health problems, including obesity.

Following are Shiffman’s answers to some of the most common questions about birth weight. For more information, visit marchofdimes.com.

I’m eating constantly. Will my baby be too big? 
If you’re healthy, probably not; you may just gain extra weight. But if you have a tendency toward diabetes or your glucose tolerance is impaired, your baby may be born larger than if your diet was more moderate. Either way, try to stick to a low-fat diet with plenty of vegetables, fruits and whole-grain foods.

When it comes to babies, how big is too big?
In terms of delivery, much depends on the size of the mother’s pelvis relative to the baby’s head. That said, the optimum weight for a newborn is more than 5.5 pounds and less than 9 or 10 pounds, certainly no larger than 11 pounds.

I’m carrying a girl. Should I expect her to be petite?
No, although girls do tend to be born smaller than boys.

I’m tiny, but my husband’s big enough to be an NFL linebacker. Will we have a big baby? A baby’s size can’t be predicted because so many factors are involved, including nutrition available in the womb. Most likely, your child will be a combination of the both of you and come out average-size.

My baby was born huge. Will he be a heavy adult?
Consider heredity: If you’re, say, 5 feet 9 inches and the dad is 6 feet 6 inches, your baby may not be overweight, just big. But if both of you are obese and you have gestational diabetes, chances are that the baby will grow up to be overweight.

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