Maternal Stress During Pregnancy Linked to Higher Autism Risk in Children, Study Finds
Mothers experiencing extreme stress during or after pregnancy may be placing their children at heightened risk of developing autism, according to a groundbreaking new study from Japan. Researchers have discovered a significant correlation between perinatal depression—psychological distress occurring around the time of pregnancy—and an increased likelihood of autistic traits in offspring.
Gender Differences in Autism Risk and Presentation
The research team from Tohoku University analysed medical data from 23,000 mother-child pairs, assessing depressive symptoms during early and mid-pregnancy as well as one month after birth. Their findings revealed that newborn girls showed the strongest association between maternal stress and autistic traits, with these female infants also more likely to be born underweight and demonstrate weaker bonds with their mothers.
However, the study noted that boys consistently displayed more autistic-like traits than girls regardless of their mother's mental health status. This gender disparity in presentation may contribute to the underdiagnosis of autism in females, a phenomenon supported by separate research published this week suggesting girls may be just as likely to be autistic as boys but less frequently diagnosed during childhood.
Biological Mechanisms Revealed Through Animal Studies
To investigate the biological underpinnings of their findings, the researchers established a stress model in pregnant mice. The stressed mice exhibited depression-like symptoms and demonstrated reduced maternal care behaviors. Their female offspring subsequently displayed autism-like behavioral patterns, including increased self-grooming and diminished social awareness.
Further analysis revealed that stressed mouse mothers had lower oxytocin levels—the hormone crucial for social bonding—in a key brain region. Their female offspring similarly showed fewer oxytocin receptors in the same brain area, potentially explaining the impaired mother-infant bonding observed.
Understanding Autism Spectrum Disorder
Autism is not an illness or disease but rather a neurodevelopmental condition characterized by different brain functioning patterns. Individuals are typically born autistic or show signs early in childhood, and autism persists throughout life. While not a medical condition requiring "cure," many autistic people benefit from support with certain challenges.
Common characteristics include:
- Difficulties with communication and social interaction
- Sensory sensitivities to bright lights or loud noises
- Challenges understanding others' thoughts and feelings
- Anxiety in unfamiliar situations or social events
- Repetitive behaviors or thought patterns
The exact causes remain unclear, though genetic factors likely play a role. Importantly, autism is not caused by bad parenting, vaccines, diet, or contagious infections.
Research Limitations and Broader Context
The Japanese researchers acknowledged study limitations including a relatively small sample size that couldn't account for cultural differences. Their findings, published in Molecular Psychiatry, emphasize that "developmental delays appear to be more common in girls with autism spectrum disorder" and underscore "the importance of screening and supporting maternal mental health."
These results align with previous research, including a British Medical Journal study of over 140,000 pregnant women that found antidepressant use during the second and third trimester nearly doubled autism risk in children. The NHS notes that while some mood changes are normal during pregnancy, antenatal depression affects many women, with symptoms including persistent sadness, irritability, appetite changes, negative thoughts about the baby, and concentration difficulties.
Growing Awareness and Service Demands
The findings emerge amid soaring demand for autism assessment services, with approximately 91,000 people aged 10-25 awaiting referrals as of March last year. Some experts attribute this increase to growing awareness of autism spectrum disorder, which only gained widespread recognition as a distinct condition this century.
In December, Shadow Health Secretary Wes Streeting called for an independent review into the rising demand for mental health, ADHD, and autism services following warnings about potential overdiagnosis. Meanwhile, Dr. Caroline Fyfe, lead author of the gender disparity study, stated: "Our findings suggest that the gender difference in autism prevalence is much lower than previously thought, due to women and girls being underdiagnosed or diagnosed late."
Experts describe these collective findings as both timely and important, supporting theories that autism remains significantly underdiagnosed in females while highlighting the critical need for early identification and support of maternal mental health beginning in pregnancy to reduce adverse developmental outcomes in children.
