Is grand multiparity associated with offsprings' hospital treated mental disorders? A 28-year follow-up of the North Finland 1966 birth cohort

Background: A child born to a grand multiparous (GMP) mother (i.e. a mother who has undergone six or more deliveries) is at increased risk of perinatal complications, but it is not known whether or not GMP status is associated with child's adulthood mental disorders. Methods: The data were obtained from the unselected, general population Northern Finland 1966 Birth Cohort (n = 11,017). The cohort members (children) were followed up prospectively to the age of 28 years. Using the National Hospital Discharge Register, a total of 89 DSM-III-R schizophrenia cases were identified, as well as 55 other psychoses, 87 personality disorders, 36 cases of alcoholism, 53 depressive disorders, and 67 anxiety and other non-psychotic disorders. The association between the mother's grand multiparity and the offspring's adult hospital-treated psychiatric morbidity was analysed using a continuation ratio model, which is a modification of logistic regression. Odds ratios were adjusted for social class, maternal antenatal depression, and wantedness of pregnancy. Results: A total of 1320 mothers (12%) were GMPs. Maternal CMP status was not associated with offspring's schizophrenia, anxiety or other non-psychotic disorders. The risk of other psychoses (OR 2.3; 95% CI 1.2-4.7), alcoholism (OR 2.0; 95% CI 0.8-4.7) and depressive disorder (OR 2.2; 95% CI 1.0-4.5) was elevated among offspring of GMP mothers. Conclusions: It is possible that the mother's GM status and the large family size associated with this are causal factors in the development of other psychoses than schizophrenia, alcoholism and depression among adult offspring.