The Claim: Mother’s Heartburn Means a Hairy Newborn

THE FACTS It is an odd adage that has stuck around for ages: women who suffer heartburn during pregnancy will have babies with full heads of hair. But doctors have long shrugged it off.

Until now, that is. In December, researchers at Johns Hopkins University conducted a study intending to put the claim to rest. To their surprise, they ended up confirming it. The study, published in the current issue of the journal Birth, followed 64 pregnant women, about 78 percent of whom reported having some heartburn. After the women gave birth, two outside observers looked at pictures of their infants and rated their levels of hair.

Of the 28 women who reported moderate to severe heartburn, 23 had babies with average or above-average amounts of hair. Conversely, 10 of the 12 women who reported no heartburn had babies with little or no hair.

Other studies have shown that in pregnant women, high levels of estrogen and other hormones can relax the sphincter at the bottom of the esophagus, causing heartburn. The same hormones, other studies show, can influence fetal hair growth.

The lead author of the study, Kathleen Costigan, who runs the fetal assessment center at Johns Hopkins, said the findings came as a shock.

“We’ve heard this claim hundreds of times, and I’ve always told people it’s nonsense,” she said. “Since the study came out, I’ve had to eat a lot of crow.”

THE BOTTOM LINE Heartburn during pregnancy may mean a greater likelihood a baby will have a lot of hair.