Study weight gain in pregnant women according to the recommendations of the American Institute of Medicine (IOM 2009) and identify the associated factors with inadequate weight gain in pregnant women in Constantine (Algeria). A prospective and longitudinal study of a cohort of 217 pregnant women aged 19 to 43 years was carried out during the entire period of pregnancy at antenatal consultation and monitoring centers in Constantine (Algeria) from December 2013 to July 2016. Their weight was measured in the first, second and third trimester. Gestational weight gain was classified as lower or meeting the IOM recommendations. Factors associated with gestational weight gain (GWG), such as pre-gestational body mass index, women's knowledge of GWG, sympathetic signs, eating habits and consumption, and maternal stress were studied. Statistics were performed using Statview™ and SPSS software. The majority of women (65.4%) had inadequate total GWG and only 34.6% of them had GWG consistent with IOM recommendations. Inadequate weight gain was more frequent in women obese before pregnancy (p<0.0001), women who reported not knowing the ideal GWG (p=0.01), had sympathetic signs (p=0.01), food aversions (p=0.0086), and insufficient vitamin, and mineral intakes (p<0.01). Inadequate GWG was also common among women with insufficient duration of sleep and living in a stressful environment. GWG is associated with a number of factors and variable relationships for each trimester of pregnancy.