Pre‐Pregnancy Energy Balance, Gestational Weight Gain, and Small‐for‐Gestational Age in Rural Gambia: the Early Nutrition and Immune Development Trial (ISRCTN49285450)
Authors: Johnson William , Elmrayed Seham AA , Prentice Andrew M , Moore Sophie E 
Published: November 2023

Background

The importance of periconceptional micronutrient status is widely recognised. Less however is known about the consequence of weight change patterns, indicative of energy balance, preceding conception, and the impact this may have on fetal growth and development. This is particularly pertinent in low‐ and middle‐income countries in which marked seasonality results in many women experiencing negative energy balance (i.e., losing weight) as they enter pregnancy.

Objective

To investigate the impact of energy balance entering pregnancy on gestational weight gain and risk of small‐for‐gestational (SGA) in rural Gambia, where there are distinct wet/hungry (June–October) and dry/harvest (November–May) seasons.

Methods

The sample comprised 599 mother‐infant dyads participating in a randomized trial of maternal nutritional supplementation, which from previous analyses we know to have had minimal effect on gestational weight gain and birth outcomes. Briefly, non‐pregnant women of reproductive age in the West Kiang region of The Gambia were invited to participate and visited monthly, for recording of their date of last menstrual period and weight. Once pregnant, women attended the clinic at a baseline “booking” visit early in gestation and subsequently at 20 and 30 weeks of gestation. Neonatal anthropometry were collected at home visits within 72 hours of birth. Pre‐pregnancy energy balance (negative or positive) was defined according to weight change (negative or positive, respectively) in the three months preceding conception. Gestational weight gain was defined according to change in weight between conception and 30 weeks of gestation. The primary outcome was SGA (< 10th percentile of INTERGROWTH‐21st standards). Regression models with adjustment for confounders were used to test the associations between 1) pre‐pregnancy energy balance and gestational weight gain, 2) gestational weight gain and SGA, and 3) pre‐pregnancy energy balance and SGA, with and without adjustment for gestational weight gain.

Results

260 women (43%) were in negative energy balance entering pregnancy and 339 women (57%) were in positive energy balance. As expected, energy balance was patterned by seasonality; 43% of the 260 women in negative energy balance were in the wet/hungry season (at the point of conception), while only 27% of the 339 women in positive energy balance were in the wet/hungry season (p < 0.001). However, even after adjusting for pre‐pregnancy height and body mass index, women in negative pre‐pregnancy energy balance demonstrated greater gestational weight gain (beta = 1.75 kg, p < 0.001), which in turn was related to decreased risk of SGA (odds ratio = 0.94, p = 0.017). Subsequently, the association between pre‐pregnancy energy balance and SGA was weak and non‐significant (p‐value > 0.8), both before and after adjusting for gestational weight gain.

Conclusion

Women in negative energy balance entering pregnancy, as a result of being in the wet/hungry season, may demonstrate greater gestational weight gain because they then spend mid‐ to late‐pregnancy in the dry/harvest season. Subsequently, they may have no increased risk of adverse birth outcomes compared to women in positive energy balance entering pregnancy.

Support or Funding Information

The ENID trial is supported by the Medical Research Council (UK), through core funding to the MRC International Nutrition Group (MC‐A760‐5QX00).