Effects of Pre-Pregnancy Body Mass Index and Gestational Weight Gain on Low Birth Weight in Omani Infants A case-control study

Objectives: this study aimed to investigate the association between pre-pregnancy maternal bodymass index (bmi), gestational weight gain and low birth weight (lbw) in babies born to a sample population of omani women. methods: a case-control study was carried out among deliveries registered between 1st may 2010 and 30th april 2011 at sultan qaboos university hospital, muscat, oman. a case was defined as a woman who delivered a low birth weight baby (<2,500 g); a control was a woman delivering a baby weighing between 2,500 and 4,000 g. a random selection of 150 cases and 300 controls was carried out using the hospital information system. maternal, pre-natal, and delivery data were extracted from the mothers’ follow-up cards. bivariate and multivariate logistic regression analyses were executed to examine the association between pre-pregnancy maternal bmi and lbw. results: the percentage of underweight mothers (bmi <18.5) was higher among the cases compared to the controls (17.3% versus 6%; p <0.001). the proportion of mothers with less-than-recommended weight gain was also higher among the cases compared to the controls (57.7% versus 33%; p <0.001). after adjustment for potential confounders, infants of underweight mothers had more than twice the risk of lbw compared to those of mothers with normal weight (odds ratio = 2.27; 95% confidence interval 1.09–4.71). conclusion: underweight omani women as well as women with less-than-recommended gestational weight gain were at higher risk of delivering lbw babies. maternal health promotion programmes should be directed towards improving mothers’ nutrition before and during pregnancies.