The relationships of seasonality in prenatal diet and physical activity and postnatal micronutrient supplementation with growth in early life

The doctoral research centered on the topic of growth restriction during the first 1,000 days of life in rural Burkina Faso. Newborns and infants with growth restriction are at an increased risk of mortality and childhood undernutrition. More specifically, we investigated the role of seasonality in prenatal nutrition and physical activity on fetal growth and the effect of postnatal micronutrient supplementation in lactating women on infant growth. The work built upon the MISAME project which consisted of two randomized controlled nutrition intervention trials in pregnant women from subsistence-farming communities in the rural health district of Hounde, Burkina Faso. The MISAME1 trial showed that prenatal supplementation with multiple micronutrients (MMN, consisting of 15 micronutrients including iron and folic acid) compared to iron and folic acid (IFA) resulted in a modest increase in birth weight (+52 g; P = 0.04) and birth length (+3.6 mm; P = 0.01). The MISAME2 trial demonstrated that prenatal supplementation with a lipid-based nutrient supplement (LNS) including MMN compared to MMN resulted in a modest increase in birth length only (+4.6 mm; P = 0.001). In the first phase of the PhD research, relationships between seasonality in maternal diet and physical activity with fetal growth restriction were explored. Both MISAME trials showed effect modifications by maternal nutritional status at baseline, with MMN compared to IFA favoring mothers with a higher BMI and LNS compared to MMN favoring underweight mothers (BMI < 18.5 kg/m²). The PhD research further explored these findings as they imply that maternal nutrition interventions can be better targeted. Maternal nutritional status typically worsens during the rainy season. Firstly, a Fourier-based analyses of the MISAME2 trial showed that the effect of the LNS supplement compared to MMN on birth length is modified by seasonality. The largest effect of the LNS supplement on birth length was found at the transition from the rainy to dry season (+13.5 mm; 95% CI: 6.5 – 20.5), in those women whose second half of pregnancy covered the rainy season. Secondly, a cross-sectional study of physical activity in pregnant women during the rainy season suggested that the increased demands of agricultural labor imposes the involvement of women in late pregnancy, including those close to term. However, we found no associations between higher compared to lower physical activity levels of women in late pregnancy with birth outcomes. Conversely, we found an approximate 50% risk reduction for a small-for-gestational age (SGA) newborn in mothers with a higher physical activity energy expenditure in the rainy season during early and mid-pregnancy (RR: 0.52; 95% CI: 0.28 – 0.98; P = 0.04). Subgroup analyses showed that the association was only apparent in multiparous women in whom a reduction up to 76% was found (RR: 0.24; 95% CI: 0.09 – 0.62; P <0.01). A large, albeit marginally significant, 70% SGA birth risk reduction (RR: 0.30; 95% CI: 0.09 – 1.01; P = 0.05) was observed in mothers who spent more time in moderate intensity physical activity. In the second phase of the PhD research, we investigated whether an increased intake of MMNs in women for three months post-delivery could improve the growth and health of their breastfeeding infants in the first year of life. Women of reproductive age have been shown to have inadequate intakes of MMNs. Yet, of all populations, lactating mothers have the highest requirements for most micronutrients and are therefore most at risk of inadequate intakes and deficiencies. A randomized controlled trial showed that supplementation of MMNs compared to the recommended iron and folic acid had no effect on the linear growth and health of infants, unless they were respectively born too small or too soon. Subgroup analyses showed that the effect on linear growth was higher and statistically significant in infants who were born SGA (β = 0.0229 length-for-age Z-score/month; 95% CI: -0.0006 – 0.0465; P = 0.057). Conversely, prematurely born infants had increased hemoglobin concentration rates (β = 0.1558 g/dL/month; 95% CI: -0.0182 – 0.3299; P = 0.079).