The heartburn during pregnency. The study, which was published in the journal Birth, involved 64 pregnant women, 78 percent of whom reported experiencing heartburn. They rated the severity of their heartburn and the researchers kept track of the results.

Then, after the women gave birth, photographs of their babies’ heads were given to the researchers, who used a scale to rate the newborns’ hair volume. As it turns out, of the 28 women who had moderate to severe heartburn, 23 of them had babies with average or above-average amounts of hair. Meanwhile, 10 of the 12 women who reported no heartburn had babies with little or no hair.

While it sounds like there’s a link between the amount of heartburn you experience and the amount of hair your baby has, it’s not necessarily a cause-and-effect relationship. In other words, it’s probably not the hair on your baby’s head that’s actually causing you to feel the burn.
Other studies have shown that high levels of estrogen and other hormones, which surge during pregnancy, can relax the sphincter at the bottom of the esophagus.

This can cause stomach acid to leak through and cause a burning sensation. Still more studies have found that these same hormones can play a role in how much hair fetuses grow in the womb. Therefore, if you have these high levels of hormones, you’re more likely to have heartburn episodes during pregnancy.