• Posted June 25, 2026

Severe Pregnancy Nausea Tied To Higher Risk Of Complications

Severe nausea during pregnancy might increase the risk of complications for both mother and baby, a new study says.

About 1% to 3% of pregnancies are severely strained by hyperemesis gravidarum (HG), the medical term for sustained nausea and vomiting while expecting, researchers recently reported in the American Journal of Epidemiology.

As a result, the pregnancies of women hospitalized for HG have a greater risk of complications, researchers found.

“We found hyperemesis gravidarum was linked to higher risk for preterm birth, anemia, smaller-than-expected babies, preeclampsia, gestational hypertension and placental abruption,” said lead researcher Rebecca Gardner, a doctoral student in epidemiology and clinical research at Stanford Medicine in California.

“Hospitalization for HG really does flag a pregnancy as being at higher risk for a range of serious complications,” Gardner said in a news release.

HG is worse than the milder nausea that affects up to 80% of all pregnancies, researchers said.

“Hyperemesis gravidarum is not just bad morning sickness; it’s severe enough to cause dehydration and significant weight loss,” Gardner said.

Women with HG struggle to eat, stay hydrated and absorb enough nutrients to support themselves and their fetus during gestation, researchers said.

“We know from other studies that women with HG don’t get as many nutrients,” Gardner said. “This could impair placental development, which we think leads to higher risk for some of the outcomes we looked for, such as preeclampsia and babies being smaller than expected at birth.”

For the new study, researchers analyzed nearly 2.5 million single-baby births in California from 2007 to 2011. About 2% of those births involved mothers who visited the ER or were hospitalized due to HG.

Results showed that women with HG were:

• 18% more likely to have preeclampsia

• 25% more likely to deliver early

• 37% more likely to be anemic

• 14% more likely to experience a placental abruption, in which the placenta becomes partly or completely detached from the uterus

Women hospitalized for HG during the second trimester of pregnancy were more likely to experience complications than those hospitalized during the first trimester, the study found.

Researchers said these results support new guidelines adopted in 2018 that encourage treating pregnancy nausea faster and more aggressively. Two medications are now approved by the U.S. Food and Drug Administration (FDA) for treating nausea and vomiting in pregnancy.

“For physicians, I think this data means that pregnancies with HG hospitalization may warrant closer monitoring for certain complications,” Gardner said.

“Pregnant women need to know that most HG pregnancies still result in healthy outcomes for the mom and baby, but HG does need to be taken seriously,” she added. “It’s important to advocate for yourself by asking your doctor if you need more monitoring or anti-nausea medication. This is not just something to push through.”

More information

The American College of Obstetricians and Gynecologists has more on nausea and vomiting during pregnancy.

SOURCE: Stanford Medicine, news release, June 22, 2026