Birthweight, preterm birth and perinatal mortality: a comparison of black babies in Tanzania and the USA

Abstract

Adverse conditions in Africa produce some of the highest rates of infant mortality in the world. Fetal growth restriction and preterm delivery are commonly regarded as major pathways through which conditions in the developing world affect infant survival. The aim of this article was to compare patterns of birthweight, preterm delivery, and perinatal mortality between black people in Tanzania and the USA. Registry-based study. Referral hospital data from North Eastern Tanzania and US Vital Statistics. 14 444 singleton babies from a hospital-based registry (1999-2006) and 3 530 335 black singletons from US vital statistics (1995-2000). Birthweight, gestational age and perinatal mortality. Restricting our study to babies born at least 500g, we compared birthweight, gestational age, and perinatal mortality (stillbirths and deaths in the first week) in the two study populations. Perinatal mortality in the Tanzanian sample was 41/1 000, compared with 10/1 000 among USA blacks. Tanzanian babies were slightly smaller on average (43g), but fewer were preterm (<37 weeks) (10.0 vs. 16.2%). Applying the USA weight-specific mortality rates to Tanzanian babies born at term suggested that birthweight does not play a role in their increased mortality relative to USA blacks. Higher mortality independent of birthweight and preterm delivery for Tanzanian babies suggests the need to address the contribution of other pathways to further reduce the excess perinatal mortality.