A large new study challenges the common belief that a mother’s health during pregnancy directly influences her child’s risk of autism. Instead, researchers found that nearly all reported links between maternal health conditions and autism can be explained by genetics, environmental factors, and access to healthcare rather than the mother’s medical history itself.
The study, led by NYU Langone Health and published in Nature Medicine on January 31, suggests that the onlypregnancy-related conditions truly associated with autism were complications affecting the fetus. However, researchers believe these complications were likely early signs of autism rather than causes of the disorder.
Examining Over 1.1 Million Pregnancies
The study analyzed medical records from more than 1.1 million pregnancies involving 600,000 mothers in Denmark. Unlike in the U.S., where medical records are scattered across different providers, Denmark consolidates all health records under a single government-issued number.
This allowed researchers to track each woman’s full medical history and examine more than 1,700 different health conditions.
From these, the researchers focused on 236 conditions that appeared in at least 0.1% of pregnancies.
No Evidence That Maternal Health Causes Autism
The study aimed to separate coincidence from cause by looking at multiple factors, including:
- Age of the mother (older mothers are more likely to have children with autism).
- Socioeconomic status (which affects access to healthcare).
- Genetics and environmental influences (such as pollution exposure).
Even after accounting for these factors, 30 maternal conditions were still linked to autism. However, when the researchers included siblings in the analysis, the associations weakened significantly. This meant that if a mother had the same condition during multiple pregnancies—but only one child developed autism—it was unlikely that her condition caused autism.
To confirm this, the researchers also examined fathers’ medical histories. Since fathers have no direct impact on fetal development, any similar link between paternal health and autism would suggest that genetics or shared environmental factors—not pregnancy conditions—were responsible.
Indeed, many of the same associations seen in mothers also appeared in fathers, further discrediting the idea that maternal health issues cause autism.
Autism Likely Starts Prenatally
After ruling out most maternal conditions, the researchers found that the only strong link remaining was with fetal complications during pregnancy. However, they believe these complications are not causing autism, but rather are early signs of it.
“The predominant hypothesis is that autism really starts prenatally,” said Dr. Magdalena Janecka, senior author of the study. “Even before a child receives a diagnosis, developmental changes have been happening the entire time.”
A Message to Mothers: You Didn’t Cause Autism
For many mothers, the idea that their pregnancy somehow caused their child’s autism has been a source of guilt and anxiety. This study offers reassurance that autism is not the result of maternal health conditions.
“Many mothers feel guilty, thinking they did something wrong during pregnancy, and it is heartbreaking,” said Janecka. “This research shows that these factors do not cause autism. Instead, our focus should be on better support for autistic children and their families.”
The findings highlight the importance of shifting research toward genetics and early brain development, rather than focusing on maternal health conditions as a cause. By better understanding how autism develops before birth, researchers hope to improve early interventions and support for children on the autism spectrum.
If you care about autism, please read studies that cats may help decrease anxiety for kids with autism and new study may develop better treatment for autism
For more information about health, please see recent studies about how to eat your way to a healthy brain, and results showing this type of food may contribute to autism.
The research findings can be found in Nature Medicine.
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