Early prenatal food supplementation ameliorates the negative association of maternal stress with birth size in a randomised trial.

Low birth weight increases the risk of infant mortality, morbidity, and poor development. Maternal nutrition and stress influence birth size, but their combined effect is not known. We hypothesized that an early invitation time to start a prenatal food supplementation program could reduce the negative influence of prenatal maternal stress on birth size, and that effect would differ by infant sex. A cohort of 1041 pregnant women, who had delivered an infant, June 2003-March 2004, was sampled from among 3267 in the randomized controlled trial, Maternal Infant Nutritional Interventions Matlab, conducted in Matlab, Bangladesh. At 8 wk gestation, women were randomly assigned an invitation to start food supplements (2.5 MJ/d; 6 d/wk) either early (~9 wk gestation; early-invitation group) or at usual start time for the governmental program (~20 wk gestation; usual-invitation group). Morning concentration of cortisol was measured from 1 saliva sample/woman at 28-32 wk gestation to assess stress. Birth size measurements for 90% of infants were collected within 4 d of birth. In a general linear model, there was an interaction between invitation time to start the food supplementation program and cortisol with birth weight, length, and head circumference of male infants, but not female infants. Among the usual-invitation group only, male infants whose mothers had higher prenatal cortisol weighed less than those whose mothers had lower prenatal cortisol. Prenatal food supplementation programs that begin first trimester may support greater birth size of male infants despite high maternal stress where low birth weight is a public health concern.