The Impact of Adherence to Prenatal Multiple Micronutrient Supplements on Gestational Weight Gain in Low- and Middle-Income Countries: A Simulation Study.

BACKGROUND

Despite the evidence that prenatal nutritional supplements increase gestational weight gain (GWG) and improve birth and pregnancy outcomes in low- and middle-income countries (LMICs), adherence to prenatal nutritional supplements is generally low among pregnant females.

OBJECTIVES

The study aimed to evaluate the impact of varying levels of adherence to prenatal multiple micronutrient supplements (MMS) on GWG using a simulation study that was designed based on the published meta-analysis.

METHODS

Simulated datasets with different sample sizes (250-4000 participant females) were generated from an assumed model to represent different proportions of females who adhered to their treatment (50%-100%). The performance metrics reported are bias, empirical variance, and mean squared error.

RESULTS

As the adherence level decreased, the average bias and the mean squared error of the estimated percent adequacy of GWG difference between those with and without supplements increased. With 2000 participants, the average bias was 0.66, 0.53, 0.40, 0.24, 0.14 for 50%, 60%, 70%, 80%, and 90% adherence, respectively. This meant that the estimated difference was significantly underestimated with 50% adherence. Results from the simulations varying the sample size and adherence level showed that at each sample size, decreasing the adherence level resulted in larger bias, and at each adherence level, the sample size does not impact the mean bias. These results also demonstrate that even with a large sample size of 4000 participants, the mean bias remains nearly as large as that observed with a smaller sample size when the adherence is low.

CONCLUSIONS

Low adherence leads to significant underestimation of the beneficial effect of prenatal MMS on GWG. Increasing the sample size does not remedy this problem. These results highlight the importance of improving adherence to prenatal nutritional implements among pregnant females in LMICs to maximize GWG, reduce low birth weight, and small-for-gestational-age birth.