Is extreme morning sickness linked to autism?

UCLA Health article

Hyperemesis gravidarum is a serious condition that causes extreme nausea and vomiting during pregnancy and affects about two percent of pregnant women.

Although it is commonly called extreme morning sickness, the symptoms can attack women anytime of the day or night. In some cases, the woman must be hospitalized for treatment with intravenous fluids or a feeding tube.

Contrary to popular belief, researchers have found pregnancy hormones hCG and estrogen are less likely to be associated with the condition than the placenta and appetite hormone GDF15 and the progesterone receptor. In addition, they have discovered that genetics play a role in who is susceptible. They are also learning how hyperemis gravidarum affects children who are exposed to it while in the womb.

Now, a study recently published in the Journal of Reproductive Toxicology shows a possible link between hyperemesis gravidarum and autism spectrum disorder, a developmental condition that affects communication and behavior.

Marlena Fejzo, an associate researcher at the David Geffen School of Medicine at UCLA and lead author on the study, explains more:

How was the study done?

In our past study of children exposed to hyperemesis gravidarum in the womb, we found an increased risk of neurodevelopmental delay in children at 8 years of age, which included attention deficit disorders, anxiety disorders, and sensory integration and processing disorders. We did not find a significant incidence of autism spectrum disorder.

In this new study, we repeated the data collection from the mothers on their children’s diagnoses at approximately 12 years of age.

What was your key finding?

Eight percent of mothers who had hyperemesis gravidarum reported a child with an autism spectrum diagnosis. None of the mothers who did not experience hyperemesis gravidarum reported a child with an autism diagnosis.

We think the numbers became noteworthy at age 12 because additional children received a diagnosis of autism spectrum disorder between the ages of 8 and 12 years.

Is this the first study to find an association between extreme morning sickness and autism?

Our findings correlate with two other studies. One Australian study showed that increasing frequency and severity of nausea and vomiting in the mother correlated with increasing severity of autism symptoms in the child. Another U.S. study identified hyperemesis gravidarum in mothers as a risk factor for autism.

What is the significance of these findings?Since early intervention for autism spectrum disorder can be critical to the child’s prognosis, larger studies are needed to determine whether autism is associated with exposure to hyperemesis gravidarum.

In the meantime, pediatricians should ask new mothers if they had a history of extreme nausea and vomiting during pregnancy and, if so, follow these children closely for signs of neurodevelopmental delay.

Should women with hyperemesis gravidarum worry?

Hyperemesis gravidarum patients do not need more to worry about when they are pregnant and feeling extremely ill. The majority of mothers did not report a child with autism spectrum disorder, so the overall risk is likely low.

What else did you find?

This was a very small study, but we did not find any evidence to support an association between common medications to treat nausea and vomiting (ondansetron, promethazine, metoclopramide) and an autism diagnosis.

What are the next steps in this research?

If larger studies confirm this association, then the next step is to understand why. The cause for this potential association is unknown, but may be due to abnormal expression of two genes, GDF15 and IGFBP7, during fetal development, or stress, nutritional deficits, and/or mother/newborn bonding after birth.

Where can I find out more about hyperemesis gravidarum?

This research was funded, in part, by the Hyperemesis Education and Research Foundation. Their website is