Accumulating evidence has highlighted the role of maternal nutritional status on fetal development, birth outcomes and child health. The Mother and Infant Nutritional Assessment (MINA) cohort is a 3-year follow-up study of pregnant women and their children in Qatar and Lebanon. This study reports on the characteristics and determinants of pre-pregnancy BMI and Gestational Weight Gain (GWG) of MINA particiants, as well as birth outcomes. A total of 272 pregnant women were recruited during their first trimester from primary healthcare centers as well as private clinics in Beirut (n = 194) and Doha (n = 147). During the first visit, data collection included pre-pregnancy weight, sociodemographic and lifestyle characteristics. The weight before delivery and neonatal outcomes were extracted from the medical records. GWG was calculated as the difference between weight before delivery and pre-pregnancy weight and was classified into insufficient, adequate, and excessive, as per the IOM criteria. Overall, 42.1% of women had a pre-pregnancy BMI≥25 Kg/m2 (58% in Qatar vs 30.8% in Lebanon, p<0.001). Only 30.2% of women had adequate GWG, while 25.7% and 44.1% of women had insufficient and excessive GWG, respectively. In the cohort 68.7% of infants had a weight adequate-for-gestational age (AGA), 6.7% were SGA and 24.6% were LGA. The proportions of LGA were higher with greater GWG (p<0.05). After adjustment, Qatari women were 3 times more likely to be overweight or obese before pregnancy while a higher education level was associated with significantly lower odds of pre-pregnancy BMI≥25 Kg/m2. Pre-pregnancy BMI≥25 Kg/m2 and regular breakfast consumption were predictors of excessive GWG (OR: 3.20, CI: 1.48-6.91; OR: 2.84, CI: 1.15-7.02, respectively). The high prevalence of pre-pregnancy overweight and excessive GWG among MINA participants underscores the need for culture-specific intervention programs to promote healthy body weight in women of childbearing age, and prevent excessive weight gain during pregnancy.