Family size and perinatal circumstances, as mental health risk factors in a Scottish birth cohort

Purpose: Higher maternal parity and younger maternal age have each been observed to be associated with subsequent offspring suicidal behaviour. This study aimed to establish if these, and other variables from the perinatal period, together with family size, are also associated with other psychiatric morbidity. Methods: Linked datasets of the Scottish Morbidity Record and Scottish death records were used to follow up, into young adulthood, a birth cohort of 897,685. In addition to the index maternity records, mothers' subsequent pregnancy records were identified, allowing family size to be estimated. Three independent outcomes were studied: suicide, self-harm, and psychiatric hospital admission. Data were analysed using Cox regression. Results: Younger maternal age and higher maternal parity were independently associated with increased risk in offspring of suicide, of self-harm and of psychiatric admission. Risk of psychiatric admission was higher amongst those from families of three or more, but, compared with only children, those with two or three siblings had a lower risk of self harm. Conclusion Perinatal and family composition factors have a broad influence on mental health outcomes. These data suggest that the existence of younger, as well as elder siblings may be important.