Severe pregnancy nausea tied to higher complication risk in California study

Pregnant patients who needed hospital or emergency care for severe nausea and vomiting faced higher risks of several pregnancy and birth complications, Stanford Medicine researchers reported. The finding matters because the condition, hyperemesis gravidarum, can identify pregnancies that may need closer medical follow-up.

The study, published in the American Journal of Epidemiology, examined nearly 2.5 million single-baby births in California from 2007 through 2011. Stanford Medicine described it as the first large U.S. population-based study focused on risks tied to hyperemesis gravidarum, often shortened to HG.

HG is a severe form of pregnancy nausea and vomiting that can cause dehydration and substantial weight loss, according to Rebecca Gardner, the study’s lead author and a Stanford Medicine graduate student in epidemiology and clinical research. Stanford Medicine said ordinary nausea affects 70% to 80% of pregnant women and usually does not leave lasting effects, while HG affects about 1% to 3% of pregnancies.

Higher risks found across several outcomes

The researchers compared pregnancies involving emergency department or inpatient care for HG with pregnancies that did not include such care, Stanford Medicine said. The analysis included 2,476,492 births, including 53,681 births, or 2.2%, in which the mother received emergency or inpatient care for HG.

After accounting for possible confounding factors, Stanford Medicine said HG was associated with higher risks of preeclampsia, gestational hypertension, preterm birth, anemia, placental abruption and babies who were small for their gestational age. Preeclampsia can lead to seizures if untreated, while placental abruption occurs when the placenta partly or fully separates from the uterus before delivery, according to the study summary.

The increases varied by complication. Stanford Medicine said patients with HG were about 18% more likely to have preeclampsia, about 25% more likely to deliver early, about 37% more likely to be anemic and about 14% more likely to have placental abruption than patients without HG.

The study also found timing differences, according to Stanford Medicine. Patients first hospitalized for HG in the second trimester had higher complication risks than those first hospitalized in the first trimester.

Nutrition may be part of the link

Stanford Medicine said HG can interfere with eating, hydration and absorption of nutrients needed early in pregnancy, including folate. Gardner said prior studies show patients with HG receive fewer nutrients, which could affect placental development and help explain outcomes such as preeclampsia and smaller-than-expected babies.

The California analysis used birth records, diagnostic codes from pregnancy and delivery care, maternal demographic information, prepregnancy body mass index and census-tract measures of social vulnerability, Stanford Medicine said. Gardner said earlier studies were often smaller and mostly based on European populations and health systems, limiting how well their findings applied to the United States.

Stanford Medicine noted that American College of Obstetricians and Gynecologists guidance for HG treatment changed in 2018, after the years covered by the data. The updated guidance encourages faster and more aggressive treatment of pregnancy nausea, and two medicines are now approved by the U.S. Food and Drug Administration for nausea and vomiting in pregnancy, Gardner said.

Gardner said more research could assess whether HG should lead clinicians to offer additional preventive care, including low-dose aspirin, which is used to reduce preeclampsia risk in some patients. She also said most HG pregnancies still end with healthy outcomes for mother and baby, while HG should be treated as a condition that warrants attention rather than something patients are expected to endure.

This story draws on original reporting from Medical Xpress.