Status: Funded - Closed
Influence of maternal nutrition before and during pregnancy on child birth outcomes
Melissa Young, B.S., Ph.D.
8. BACKGROUND: Maternal undernutrition is a key determinant of poor fetal growth, low birthweight, and increased infant morbidity and mortality and has long-term adverse consequences on her child’s motor and cognitive development and lifelong health. GAP: Reliable data prior to conception are rare and the role of maternal pre-pregnancy nutritional status in fetal growth remains poorly understood. While studies have examined the impact of total gestational weight gain on adverse birth outcomes, we lack an understanding of the relative importance of trimester specific weight gains. HYPOTHESIS 1: Maternal pre-pregnancy weight and body composition are associated with birth outcomes. 2: The relative importance of maternal weight gain for birth outcomes varies across three periods of the continuum from preconception to delivery: Early (pre-pregnancy, PP - < 20 weeks gestation), Mid (20 - 29 weeks), Late pregnancy (30 weeks - delivery).
METHODS: Prospective maternal anthropometry, weight gain data, fetal ultrasounds and infant size at birth data were collected on women starting pre-pregnancy through delivery using secondary data from a randomized controlled trial evaluating weekly preconceptional micronutrient supplements (PRECONCEPT) on maternal and child health outcomes in Thai Nguyen province, Vietnam (n=1436). Maternal conditional weight gain (CWG) allows for the influence of weight gain in three distinct periods: Early (pre-pregnancy, PP - < 20 weeks gestation), Mid (20 - 29 weeks), Late pregnancy (30 weeks - delivery). CWG are uncorrelated, conditional measures, independent of prepregnancy BMI, which allows for each time period to be examined independently. Fetal anthropometry was obtained by trained physicians during early, mid and late pregnancy from ultrasound measures (head circumferences-HC, biparietal diameter-BD abdomen circumference-AC, and femoral length-FL) and were converted to Z scores using the reference values from the INTERGROWTH-21st Project. Risk for small for gestational age (SGA), < 10th percentile based on INTERGROWTH-21st reference, and infant anthropometry (weight, length, head circumference, mid upper arm (MUAC) and abdomen circumferences) were assessed at birth. Generalized linear models, adjusting for potential confounding factors (pre-pregnancy BMI, maternal age, education, treatment group, child gender, household SES, time from enrolment to conception) were used to examine the impact of maternal nutrition on fetal and infant growth.
Maternal prepregnancy weight was the strongest preconception anthropometric indicator predicting infant birth size. A 1 standard deviation (SD) increase in prepregnancy weight (5.4 kg) was associated with a 283 g (95%CI: 279–286) increase in birthweight. A similar and independent association was observed with birthweight for an increase of 1 SD in gestational weight gain (4 kg) (250 g; 95% CI: 245–255). Women with a prepregnancy weight of <43 kg or who gained <8 kg during their pregnancy were more likely to give birth to a SGA (OR 2.9: 95%CI 1.9–4.5, OR 3.3: 95%CI 2.2–5.1) or LBW infant (OR 3.1: 95%CI 1.5–6.2, OR 3.4: 95%CI 1.6–7.2), respectively.
Early maternal weight gain (CWG <20 weeks) significantly impacts fetal growth during early (BD), mid (HC, BD, FL) and late (HC, BD, AC, FL) pregnancy. Early maternal weight gain has nearly twice the impact on late fetal growth for HC, BD, FL compared to mid pregnancy weight gain (with exception to AC). Late pregnancy weight gain has no significant impact on late fetal growth. Early maternal CWG had the greatest association on all infant birth outcomes. For infant birth weight, a 1 SD increase in weight gain in early pregnancy had nearly 3 times the impact compared to the same gain in late pregnancy (111 vs 39 g). Early weight gain (1 SD increase in CWG) was associated with a 48% reduction in risk of SGA and had nearly twice the impact compared to late pregnancy weight gain.
IMPACT: There is a need to target women before or early in pregnancy to ensure adequate nutrition and weight gain to maximize impact fetal growth and infant birth size.
United States, Vietnam