Background: malnutrition and extremely low body mass index (BMI) are neglected problems with many underlying obstetrics complications including infertility, miscarriage, low birth weight, intrauterine growth restriction, small head circumference, premature birth, increased risk of stillbirth, postpartum depression and anxiety. It’s advisable a multidisciplinar approach to these patients, preferable before the pregnancy. Cases: we reported two cases of pregnant women with extremely low BMI, describing the management and perinatal outcomes. Conclusions: our aim was to emphasize the challenges in obstetric care in such specific group of patients and the impact of extremely low maternal BMI on early pregnancy outcome. A multidisciplinary approach in such a highly vulnerable group of pregnant women is necessary to ensure a favorable early perinatal outcome and to avoida long term consequences.