Effect of stress on birth weight in two Johannesburg populations.

The effect of stress on birth weight was assessed in mothers delivering at Johannesburg (predominantly white) and Baragwanath (exclusively black) Hospitals. The Social Readjustment Rating Scale of Holmes and Rahe was used to assign maternal stress scores established during an interview conducted within 36 hours of delivery. Only mothers without medical problems who had delivered liveborn infants were included. Maternal age, obstetric history, smoking history and stresses present during the 12 months preceding delivery were recorded. Of 535 Johannesburg and 662 Baragwanath mothers studied, 48% and 55% respectively reported significant stresses. Analysis of the two groups revealed that for the Johannesburg mothers, smoking, cumulative stress score and previous preterm birth were important determinants of birth weight. Of the stress factors studied, marital separation and death of a spouse were significantly associated with a lower birth weight. For Baragwanath mothers the major determinants of low birth weight were maternal age, loss of income through being dismissed from work, or having to leave school as a consequence of the pregnancy.