A new study indicates the rising C-section rate might be due in part to doctors overestimating babies' birth weights.

newborn baby on scale
Credit: Shutterstock

When I was at the end of my first pregnancy, my doctor told me my baby would weigh at least 8 pounds, if not more. She weighed just over 6 pounds. Barely.

[Scratches head.]

Well, it turns out doctors often wrongly estimate babies' weights in utero, which may play into the escalating C-section rates in this country. Because who wants to push a 10-pounder out of your, um, you know.

The thing is, according to the American College of Obstetricians and Gynecologists, because estimating baby's weight during pregnancy is done using ultrasound, it isn't very accurate. This is especially true during the third trimester, when a baby's weight becomes most important for delivery planning.

Consider a recent study that looked at 2,000 new moms and found four in five were told their newborns would be large; but they weren't! In this study, researchers defined "large" as weighing more than 8 pounds, 13 ounces, which is the medical definition. (Meanwhile, ACOG defines a large baby as weighing more than 11 pounds. Ouch.)

Women who are told their babies will be large often request C-sections. Or, doctors will recommend that women who they believe are carrying larger infants get C-sections. So you can see how wrongly estimating the weights becomes an issue.

Unfortunately for now, there is no better way to estimate a baby's weight. But we know C-sections carry risks for both mother and baby, which are worth considering if you think you may have a large baby. Most importantly, don't push to induce early or have a C-section before full-term, says the American College of Obstetricians and Gynecologists, because babies born before they're ready are at risk for complications, including respiratory distress. The thought of delivering a large baby may be scary, but keep in mind that your doctor should closely monitor you during labor to decide when—and if—a C-section or other intervention is needed.

Melissa Willets is a writer/blogger and a mom. Follow her on Twitter (@Spitupnsuburbs), where she chronicles her love of exercising and drinking coffee, but never simultaneously.