Birth Intervals, Gestational Age, and Low Birth Weight: Are the Relationships Confounded?

Abstract

Regardless of whether low birth weight (2500 grammes or less at birth) is caused by intra-uterine growth retardation or pre-term birth, the condition remains one of the strongest predictors of neonatal and infant mortality. Using data from 2,234 post partum women in two hospitals belonging to the Mexican Social Security Institute, this study examines the relationship between birth intervals and low birth weight. The analysis controls for a number of potentially confounding factors, including mother's age and physical characteristics, outcome of previous pregnancy, and gestational age. The results indicate that although gestational age is a significant predictor, it has very little effect on the relationship between birth intervals and low birth weight. A birth interval 90 per cent below one year is associated with an increase in the odds of low birth weight, and an interval of 13 to 21 months is associated with an increase of 65 per cent.