Effect of a micronutrient-rich snack taken preconceptionally and throughout pregnancy on ultrasound measures of fetal growth: The Mumbai Maternal Nutrition Project (MMNP)

Abstract

Improving micronutrient intakes of under-nourished mothers in low- and middle-income countries increases birth weight, but there is little data on the nature and timing during gestation of any effects on fetal growth. Ultrasound measures of fetal size were used to determine whether and when a food-based supplement affected fetal growth. Non-pregnant women living in Mumbai slums, India (N = 6,513), were randomly assigned to receive either a daily micronutrient-rich snack containing green leafy vegetables, fruit, and milk (treatment) or a snack made from lower-micronutrient vegetables (control) in addition to their usual diet from before pregnancy until delivery. From 2,291 pregnancies, the analysis sample comprised 1,677 fetuses (1,335 fetuses of women supplemented for ≥3 months before conception). First-trimester (median: 10 weeks, interquartile range: 9-12 weeks) fetal crown-rump length was measured. Fetal head circumference, biparietal diameter, femur length, and abdominal circumference were measured during the second (19, 19-20 weeks) and third trimesters (29, 28-30 weeks). The intervention had no effect on fetal size or growth at any stage of pregnancy. In the second trimester, there were interactions between parity and allocation group for biparietal diameter (p = .02) and femur length (p = .04) with both being smaller among fetuses of primiparous women and larger among those of multiparous women, in the treatment group compared with the controls. Overall, a micronutrient-rich supplement did not increase standard ultrasound measures of fetal size and growth at any stage of pregnancy. Additional ultrasound measures of fetal soft tissues (fat and muscle) may be informative.

Keywords: India; fetal growth; food-based supplement; pregnancy; randomised controlled trial; ultrasound.

Figure 1

Flowchart of participants in the Mumbai Maternal Nutrition Project (MMNP). Shaded boxes indicate women who started supplementation ≥3 months before their last menstrual period (LMP)

Figure 2

Head circumference, biparietal diameter, femur length, and abdominal circumference according to gestational age (weeks) in relation to the 3rd, 10th, 50th, 90th, and 97th centiles from the INTERGROWTH‐21^st standards. Biparietal diameter in our study was measured differently from the INTERGROWTH‐21^st project; hence, the value could not be formally compared with the provided international standards. IG = INTERGROWTH

Figure 3

Standardised regression coefficients β (and 95% confidence interval) for the effect of the intervention on HC, BPD, FL, and AC at visits 1, 2, and 3. Results are taken from the unadjusted analysis (differences are computed as treatment − control. A positive β indicates larger size in the intervention group). Circles refer to the mean difference in fetal size between control and treatment groups in the intention‐to‐treat analysis. Triangles represents the same values estimated in the per‐protocol analysis. AC = abdominal circumference; BPD = biparietal diameter; FL = femur length; HC = head circumference; ITT = intention‐to‐treat; PP = per‐protocol

Figure 4

Effect of the intervention on BPD and FL at visit 2 according to maternal parity. Values are means; error bars indicate 95% confidence intervals. Panels (a) and (b) refer to the results obtained in the intention‐to‐treat analysis. Panel (c) summarises the results from the per‐protocol analysis (women who started supplementation ≥3 months before their last menstrual period date). The numbers in each figure summarise the mean difference between treatment and control of the considered measure according to parity. BPD = biparietal diameter; FL = femur length