The effect of pre-pregnancy body mass index on gestational weight gain and pregnancy outcome in Gorgan, North Iran

Abstract

This study was performed to assess the role of pre-pregnancy BMI on gestational weight gain and birth weight. A prospective study was conducted in 315 pregnant women with the mean age of 26.6±5.6 years who attended to two urban and rural health care centers in Gorgan, North of Iran. Patients with gestational diabete and pre-eclampsia were excluded. Data on pregnancy weight gain, height, age, smoking, parity, birth weight and mother's educational status were obtained by a trained health worker and some questionnaires. Then women were divided to four subgroups based on pre-pregnancy BMI as underweight, normal, overweight and obese. Participants were also divided to three subgroups on the basis of their educational status. Gestational weight gain was studied in each of these groups and compared in regard to pre-pregnancy BMI and educational status of the women. Weight gain below the lower cut-off of IOM was 47.7, 47 and 20.3% in underweight, normal and overweight groups, respectively. Normal weight gain according to IOM was 40.9, 34.7, 52.5 and 33.3% in underweight, normal, overweight and obese groups, respectively. Mean birth weight was significantly higher in women with normal pre-pregnancy BMI and the prevalence of LBW was much more in women with low pre-pregnancy BMI (p = 0.002). Also, highly educated women (>12 years of schooling) gained more weight during pregnancy significantly. This study showed a considerable proportion of women with underweight and normal weight in study area have lower gestational weight gain that recommended by IOM, which can be a cause for LBW neonates.