Morning sickness stinks, but it could be a good sign

Nobody wants to feel the nausea and vomiting that comes with morning sickness, but a recent study reveals that there may be a hidden advantage to all of that suffering.

Scientists have discovered the strongest evidence yet that vomiting and nausea during pregnancy are related with a lower chance of miscarriage, corroborating the widely held belief that morning sickness indicates that the baby is developing normally.

“It’s a prevalent misconception that nausea signifies a healthy pregnancy, but there wasn’t a lot of high-quality research to support this idea,” says epidemiologist Stefanie N. Hinkle of the National Institutes of Health in the United States.

“Our study assesses symptoms from the first weeks of pregnancy, soon after conception, and demonstrates that nausea and vomiting are associated with a lower chance of pregnancy loss.”

While earlier studies have looked into the link between morning sickness and miscarriage rates, Hinkle claims that this is the first time nausea and vomiting symptoms have been addressed in depth during the initial weeks of pregnancy, when up to 80% of women suffer morning sickness.

The study looked at data from the Effects of Aspirin in Gestation and Reproduction (EAGeR) experiment, which looked at whether low aspirin dosages could reduce the likelihood of miscarriage in 797 women who had had one or two previous pregnancy losses.

The participants, all of whom had a positive pregnancy test at the start of the research, kept daily diaries of whether they had nausea or vomiting from the second to the eighth week of their pregnancies.

From the eighth week of pregnancy to the 36th, individuals noted their symptoms in a monthly questionnaire.

In the experiment, 188 of the 797 pregnancies resulted in miscarriage. However, the researchers discovered that women who experienced nausea by the eighth week (57.3 percent of the cohort) were 50% less likely to lose their pregnancy than those who did not.

Women who experienced both nausea and vomiting by the eighth week (26.6 percent) were 75 percent less likely to miscarry than those who did not experience both symptoms.

In comparison to prior research that did not thoroughly evaluate women’s symptoms during the first eight weeks of pregnancy, the findings could be quite useful. The researchers also considered other factors that may influence miscarriage rates, such as alcohol consumption and chromosomal abnormalities in the baby.

“These findings overcame earlier analytic and design limitations and constitute the most definitive data available to date suggesting the protective link between nausea and vomiting in early pregnancy with the risk of miscarriage,” the researchers write in their report.

However, it is important to note that all of the women who took part in the study had already suffered one or two miscarriages, which cannot be stated for every woman who wishes to have a baby and may make it difficult to interpret the results with the ‘typical woman’ in mind.

The researchers however admit that their little study “was conducted within a very homogeneous sample of women, which may restrict generalizability.”

It’s also worth noting that all research of this type rely on participants accurately self-reporting their symptoms.

Despite these constraints, there is certainly a link between morning sickness and reduced miscarriage rates here, although the researchers aren’t sure why.

“We hypothesize that there is a more direct biological correlation going on between nausea and vomiting and pregnancy loss,” Hinkle told Time’s Alice Park, “but our data can’t tell us exactly what that is.”

Morning sickness symptoms, according to the researchers, “may be part of an evolutionary benefit to adjust one’s nutritional intake, enhance ingestion of carbohydrate-rich foods, or avoid intake of possibly teratogenic substances.”

It’s also plausible, according to the researchers, that morning sickness is related to the activity of the hormone human chorionic gonadotropin (hCG) – or that nausea and vomiting are signals for healthy placental tissue.

“As a result, decreased nausea and vomiting may indicate failing pregnancies, with lower hormone levels causing nausea and vomiting,” they write.

More research is needed to determine the underlying biological explanations of this apparent link, but the team is confident that their findings can bring some consolation to expecting moms who are struggling, especially in the early stages.

“It’s difficult the first time you get pregnant, and then you get ill and weary,” Hinkle told Time. “This should bring some comfort and confidence to ladies suffering these symptoms that their pregnancy is OK.”

By the same token, the researchers are quick to point out that there’s nothing wrong with not experiencing morning sickness – in other words, no one should feel like they’re missing out on some kind of ‘protective effect,’ because researchers are only now beginning to investigate what’s going on with this association.

“Not all pregnancies are the same, and every individual is different,” Hinkle told The Atlantic’s Adrienne LaFrance. “Just because they don’t have symptoms does not imply they won’t have a loss.”