Objective: To assess the effect of body mass index (BMI) on the tendency of pregnant women to vomit and on their general condition during pregnancy. Study design: We included patients in this study who presented to our gynecological emergency room and clinic during their first trimester of pregnancy. All women completed a questionnaire assessing obstetrical and physical characteristics, including gravidity, parity, gestational age, height and weight for BMI calculation. Women were requested to report the number of vomiting episodes per day and their general condition using a 1 to 10 scale (1- good, 10- bad). Patients were allocated to either a low- frequency group (0- 1 vomiting episodes per day) or to a high- frequency group (2 and more vomiting episodes per day). Results: Sixty- one consecutive women were included in the study. The low frequency group consisted of 35 women and the high frequency group included the remaining 26 women. The BMI was significantly lower in the high frequency group as compared to the low frequency group (21.8 ± 3.5 versus 24.4 ± 4.7, respectively; P < 0.05). Patients in the high frequency group also reported a worse general condition than those in the low frequency group (7.6 ± 2.2 versus 3.5 ± 2.1, respectively; P < 0.05). Conclusion: Patients with higher frequency of vomiting episodes during the first trimester of pregnancy tend to have a lower BMI score and a worse general condition than patients with low frequency of vomiting episodes. Objective: To assess the effect of body mass index (BMI) on the tendency of pregnant women to vomit and on their general condition during pregnancy. Study design: We included patients in this study who presented to our gynecological emergency room and clinic during their first trimester of pregnancy. All women completed a questionnaire assessing obstetrical and physical characteristics, including gravidity, parity, gestational age, height and weight for BMI calculation. Women were requested to report the number of vomiting episodes per day and their general condition using a 1 to 10 scale (1- good, 10-bad). Patients were allocated to either a low-frequency group (0-1 vomiting episodes per day) or to a high- frequency group (2 and more vomiting episodes per day). Results: Sixty-one consecutive women were included in the study. The low frequency group consisted of 35 women and the high frequency group included the remaining 26 women. The BMI was significantly lower in the high freque ncy group as compared to the low frequency group (21.8 ± 3.5 versus 24.4 ± 4.7, respectively; P <0.05). Patients in the high frequency group also reported a worse general condition than those in the low frequency group (7.6 ± 2.2 versus 3.5 ± 2.1, respectively; P <0.05). Conclusion: Patients with higher frequency of vomiting episodes during the first trimester of pregnancy tend to have a lower BMI score and a worse general condition than patients with low frequency of vomiting episodes.