The form of morning sickness in question is called hyperemesis gravidarum, and it occurs in less than 5% of pregnancies, explained a team at Kaiser Permanente Southern California. Women with the condition have intense nausea and can't keep food or fluids down, which can lead to dehydration and poor nutrition during pregnancy.
The new study -- involving data on nearly 500,000 pregnant women and their children born between 1991 and 2014 -- "suggests that children born to women with hyperemesis may be at an increased risk of autism," said lead author Dr. Darios Getahun.
The study couldn't prove cause and effect, but it found a 53% increased risk of a child being diagnosed with autism spectrum disorder if their mother suffered from hyperemesis gravidarum.
There was one silver lining from the finding, Getahun said: "Awareness of this association may create the opportunity for earlier diagnosis and intervention in children at risk of autism."
The earlier that women experienced severe morning sickness, the stronger the tie to autism. Getahun's team found that hyperemesis gravidarum in the first and second trimester was linked with autism risk in offspring, but not when it was diagnosed in the third trimester.
Girls were more likely to develop autism than boys if their mothers had severe morning sickness, the findings indicated.
