Does Morning Sickness Make Your Baby Smarter?

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A recent headline promised, "Women Who Suffer From Morning Sickness Are More Likely to Have Babies With High IQ." This is great news, right? If you're going to spend weeks or months nauseous and throwing up, it helps to know your suffering is making your kid smarter. But what if you go through pregnancy without throwing up? Depending on which study you read, 10 percent to 50 percent of women don't get morning sickness (a slightly baffling range). Does that make their kids dumber?

Of course not. The headlines oversimplified a new Journal of Pediatrics study that—at this point—hasn't proven anything per se about the impact of morning sickness on IQ. Such has been the case with many morning sickness headlines over the years. A few examples: "Morning Sickness Vomiting Risks Birth Defects" and "Morning Sickness Lowers Risk of Breast Cancer."

Though the first case of morning sickness was documented in 2000 B.C., scientists still don't know exactly why it happens or how it works (or, for that matter, why it's called morning sickness, since it happens any time of day and is a normal part of pregnancy, not a sickness). According to biologist Samuel Flaxman, who studies the phenomenon from an evolutionary perspective, morning sickness was ignored well into the 20th century because it was believed to be a psychological problem that didn't warrant study.

About 1 percent of morning sickness cases are an extreme form called hyperemesis gravidarum, which causes relentless vomiting, weight loss, and dehydration and can require hospitalization. The vast majority of cases aren't dangerous, but they still have obvious downsides-physical and economic costs. (One study found that women lose nearly 14.5 million hours of work each year to morning sickness.) But there is one real upside: The sicker a woman is during pregnancy, the less likely she is to miscarry. This doesn't mean women without morning sickness are likely to miscarry. They deliver fine 90 percent of the time. But it does mean that morning sickness is associated with healthy pregnancies

There is extensive scientific debate over why morning sickness exists. Some believe it's simply a side effect of the hormonal change that comes with being pregnant, but several studies indicate that morning sickness evolved as a way to protect embryos. Flaxman has found that nausea and vomiting in pregnancy are triggered by foods that posed the greatest risk to our ancestors' fetuses, including meats (which could contain dangerous bacteria, fungi, or viruses) and strong-tasting vegetables (which often get their taste and odors from natural chemicals that are toxic in large amounts).

The results of the recent Journal of Pediatrics study might provide another piece of evidence in favor of the "embryo protection" argument. But it might not. The point of that study was actually to look at the long-term safety of Diclectin, the most common morning sickness drug used today. And it found that the drug Diclectin was safe. (It was funded in part by the company that makes Diclectin, which the study's co-author is a paid consultant for.)