Grandmother's pregnancy complications and autism spectrum disorders in grandchildren, a California multigenerational cohort study

Background Pregnancy complications have been associated with offspring autism spectrum disorders (ASD). There has also been increasing evidence for multigenerational risk factors of ASD. Methods In a multigenerational California birth cohort of 1,740,379 mother–child pairs, we investigated pregnancy complications when the grandmother was pregnant with the mother's generation and their associations with ASD in grandchildren. We estimated odds ratios (ORs) and 95% CIs using logistic regression. Results The odds of ASD in grandchildren were higher among grandmothers who experienced pregnancy hypertensive disorders (OR, 1.23; 95% CI, 1.12–1.36) or infections (OR, 1.14; 95% CI, 1.01–1.28) compared to grandmothers who did not have the respective condition in pregnancy. The odds of ASD in grandchildren were also higher among mothers born prematurely (OR, 1.06; 95% CI, 1.02–1.11) compared to mothers born at term and elevated among mothers born with low birth weight (OR, 1.05; 95% CI, 1.00–1.11) compared to mothers with normal birth weight. Conclusions ASD risk in grandchildren is higher among grandmothers who experienced hypertensive disorders or infections when pregnant with their daughters. Future studies are needed to explore the biologic underpinnings of possible multigenerational mechanisms.