Parental Age and Childhood Risk for Cerebral Palsy in California.

OBJECTIVE: To investigate the associations between maternal or paternal age at the time of delivery and offspring's risk for cerebral palsy (CP) in California.

STUDY DESIGN: We conducted a population-based, case-control study that included 8,736 singleton CP cases and 90,250 singleton controls, matched by sex and birth year selected from California birth certificate records from 1994 to 2010. We estimated odds ratios (OR) and 95% confidence intervals (CIs) for CP diagnosis according to maternal and paternal age recorded on the birth certificates. Causal mediation analysis was performed to estimate direct and indirect effects of parental ages on CP with preterm delivery as a potential mediator.

RESULTS: Children born to younger mothers (≤19 years) or older mothers (35-39 years; ≥40 years) had a higher risk of CP compared with children of mothers aged 25-29 years (ORs ranging from 1.13 to 1.59). Compared with paternal age 25-29 years, older paternal age (40-44 years; ≥45 years) was also associated with an increased risk for CP independent of maternal age. When analyzing jointly using both parents of ages 20-34 years as the reference, the highest risk was estimated for older parents (≥35 years). Preterm birth was estimated to mediate 19-34% of the total effects between maternal or paternal age and offspring CP risk.

CONCLUSION: Young maternal age and an older age in either or both parents were associated with a higher risk of CP in their children. Although preterm birth was a mediator, additional factors related to parental age need further exploration to explain risk of CP.