Effect of Maternal Exposure to Seasons during the Second and Third Trimesters of Pregnancy on Infant Birth Weight in Rural Bangladesh.

BACKGROUND

Pregnant women belonging to agricultural communities of low- and middle-income countries often face seasonal food insecurity and energy stress.

OBJECTIVES

We aimed to investigate the effect of maternal exposure to different seasons during the second and third trimesters of pregnancy on infant birth weight in rural Bangladesh.

METHODS

Information on 3831 singleton live births was obtained from the electronic databases of Matlab Health and Demographic Surveillance System and Matlab hospital of the International Centre for Diarrhoeal Disease Research, Bangladesh. We collected information on all term births from July 2011 to June 2015 and excluded congenital anomalies and observations with missing data. Each year was divided into 3 distinct seasons: the post-aman harvest period (January-April), the height of the monsoon (May-August), and the post-aus harvest period (September-December). Seasonal exposure was measured in weeks, and multivariable linear regression models were fitted to determine the independent effect of each week of exposure of different seasons during the second and third trimesters of pregnancy on birth weight.

RESULTS

We observed peak birth weight in the post-aman harvest season, especially among infants born in March (mean ± SD: 2930.5 ± 462.1 g), and the lowest birth weight in the month of July (2830.6 ± 385.4 g) during the monsoon season. Regression analysis showed that exposure to the post-aman harvest season during the third trimester, and the post-aus harvest period during the second trimester of pregnancy had significant positive effects on birth weight. In the final adjusted model, each week of exposure to the post-aman harvest season during the third trimester was associated with a 6.3-g (95% CI: 1.6, 10.9 g;  = 0.008) increase in birth weight.

CONCLUSIONS

Infants born to women who were exposed to the post-aman harvest season for the entire third trimester (14 wk) were associated with 88.2-g higher weight at birth. Further investigations into the complex interplay between seasonal energy stress, maternal, and fetal nutrition and measures to alleviate it are warranted.