Effects of pre-pregnancy body mass index and gestational weight gain on low birth weight in Omani infants : a case-control study

Abstract EN

Objectives : This study aimed to investigate the association between pre-pregnancy maternal body mass 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.