[Maternal weight gain during pregnancy. Relation to prepregnancy weight]

To describe the weight gain during normal pregnancy and to evaluate the relationship between maternal pregravid weight and gestational weight change.

The study population consisted of 1443 healthy women who delivered of singleton, live infants. Pregravid weight was determined on the basis of maternal reporting and categorized into four categories using the following BMI cut points (kg m-2): underweight (< 19.8), normal weight (19.8-26.0), overweight (26.1-29.0), obesity (> 29.0). Length of gestation was first determined from the onset of the last menstrual period. Weight gain by gestational age: the woman's pregravid weight was subtracted from the weight measured at each visit. Total weight gain was calculated from the last weight measured.

The mean (+/- SD) total amounts of weight gained by gestational week were 0.9 +/- 0.7 kg by 12 weeks, 7.5 +/- 2.7 kg by 28 weeks, and 12.9 +/- 3.8 kg by 40 weeks. Weight gain curve for this sample of women was linear. Weight curves in groups of women who differed in prepregnancy weight status showed similar linear trends. Compared with normal-weight women, obese and overweight women gained less during pregnancy (13.3 kg vs 11.8 kg, 12.2 kg, respectively).

Total weight gain in study population was similar to weight gain in other populations reported in publications. There was a tendency for overweight and obese women to gain weight at a lower rate, thus result in a overall lower total weight gain.