[Preterm delivery in relation to combined pregnancy weight gain and prepregnancy body mass]

To investigate association of preterm delivery with rate of pregnancy weight gain and prepregnancy body mass among polish women.

28,152 mothers from the 2001-2002 countrywide perinatal register. Delivery before 37 weeks of gestation was considered as preterm. Relation between preterm delivery and body mass, rate of weight gain, maternal age, place of residence, marital status, education, parity, mode of delivery were examined in healthy women (without medical conditions potentially related to preterm delivery (18,891)). Association of preterm delivery with the factors was expressed as odds ratios (OR). Within group of vaginal delivery dependence of preterm delivery on rate of pregnancy weight gain and prepregnancy body mass was adjusted for above factors as potential confounders.

In healthy vaginal delivering women odds ratios of preterm delivery adjusted for socio-economical potential confounders were computed: for low pregnancy weight gain and underweight OR=1.93 (CI=1.7 ; 2.2), for low pregnancy weight gain and average-weight or overweight OR=1.15 (CI=1.1 ; 1,2), for average or high pregnancy weight gain and underweight OR =1.27 (CI =1.2 ; 1.4) (reference level: average-weight or overwaight and average or high pregnancy weight gain).

Low rate of pregnancy weight gain and prepregnancy underweight increased risk of preterm delivery.