Objectives: The aim of the study was to examine relation between maternal prepregnancy BMI, pregnancy weight gain and infant birthweight.
Materials and methods: In 1998 the questionnaire was sent to 227 women who were pregnant in 1993.
Results: 56.4% of the women under study responded the questionnaire. We excluded 33 answers because of miscarriage, stillbirths, twin pregnancies and also missing data. In the remaining 95 women 37.9% had low prepregnancy BMI (< 19.8 kg/m2). 83 women gave birth to a child at term. There was a statistically significant difference in mean birthweight of infants born by women of various prepregnancy BMI (BMI < 19.8 kg/m2, 19.8-26 kg/m2, > 26 kg/m2) and also of various pregnancy weight gain (according to IOM recommendations). Underweight women gave birth to infants of lower mean birthweight than women of normal or excessive weight (p<0.05). 10.7% of underweight women gave birth to infants of low birthweight (< 2500 g). None of the women who were not underweight before pregnancy gave birth to a child of low birthweight. Women of low pregnancy weight gain gave birth to infants of lower mean birthweight than women of normal or excessive weight pregnancy weight gain. It seems that lower birth weight of infants could result from lower maternal energy, protein, calcium and iron consumption.
Conclusions: 1) Large proportion (37.8%) of women under study were underweight before pregnancy. 2) Birthweight was related to maternal prepregnancy BMI and pregnancy weight gain. Women who were underweight before pregnancy and those whose weight gain was too low gave birth to smaller infants than women who were not underweight before pregnancy and those who gained more weight during pregnancy.