Children conceived in winter and spring had increased risk of cerebral palsy


An increased risk of cerebral palsy was observed in children conceived in the winter and spring compared to summer, according to a recent study published in JAMA Network Open.

Children conceived in winter and spring had increased risk of cerebral palsy | Image Credit: © Syda Productions - © Syda Productions -

Children conceived in winter and spring had increased risk of cerebral palsy | Image Credit: © Syda Productions - © Syda Productions -

Article highlights

  • Winter and spring conception slightly increase the risk of cerebral palsy in children.
  • A California study involving over 4 million births aimed to understand the impact of conception season on CP risk.
  • CP risk is higher in children born to older, obese, Black, Hispanic mothers, or those with lower education who smoked during pregnancy.
  • CP risk is 9-10% higher in fall/winter conceptions, with the highest risk in January, February, or May compared to July.
  • This suggests a link between seasonal environmental factors and CP risk, especially in high-risk neighborhoods and among minority populations, warranting further research.

According to a recent published in JAMA Network Open, children conceived in the winter and spring experience a slight increase in cerebral palsy (CP) risk.

CP is the most common neuromotor and physical disability in children, with 2 to 3 per 1000 live births impacted in the United States. Currently, there is little data on the etiological causes of CP. However, investigating seasonal patterns of the condition may provide further understanding on how seasonally varying environmental risk factors impact disease risk.

Investigators conducted a cohort study in California to bridge the information gap about how season of conception impacts CP risk. The study cohort included 4,652,013 live births which occurred in California between 2007 and 2015.

Excluded birth records included records missing maternal residential address or last menstrual period information and records with potential cofounding errors. There were 4,468,109 live births included in the final analysis, of which 4697 children had CP.

CP was defined by study authors as, “a group of nonprogressive lesions or disorders in the brain that are characterized by paralysis, spasticity, or abnormal movement and/or posture control that manifested in early childhood.”Cofounders were determined by extracting maternal and child sociodemographic data.

Conception data was estimated using the child’s date of birth and length of gestation based on the last menstrual period. Winter was defined as January to March, spring as April to June, summer as July to September, and fall as October to December.

Of participants, 51.2% were male, 28.3% had a maternal age of 19 to 25 years and 27.5% of 26 to 30 years, 5.6% were Black, 13.5% Asian, 49.8% Hispanic, and 28.3% non-Hispanic White. CP was seen more often in children born to older, obese, Black, and Hispanic mothers, as well as mothers with a lower education level or who smoked during pregnancy.

The risk of CP was estimated as 9% to 10% higher among children conceived in the fall or winter compared to those conceived in the summer. When evaluating specific months, the risk of CP was 15% greater for children conceived in January, February, or May, than those conceived in July.

These associations were strengthened among children born to mothers living in high-risk neighborhoods based on sociodemographic factors. Racial and ethnic minority status and lower maternal education also strengthened these associations.

These results indicated an increased risk of CP among children conceived in the winter or spring seasons compared to the summer season. Investigators recommended future etiological research on CP to evaluate exposure effects from seasonally varying environmental risk factors.


Zhuo H, Ritz B, Warren JL, Liew Z. Season of conception and risk of cerebral palsy. JAMA Netw Open. 2023;6(9):e2335164. doi:10.1001/jamanetworkopen.2023.35164

This article was initially published by our sister publication, Contemporary OB/GYN®.

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