THE IMPACT OF PREGNANCY ON THE LONG-TERM WEIGHT-GAIN OF PRIMIPAROUS WOMEN IN ENGLAND

OBJECTIVES: To investigate the impact of pregnancy on long-term weight gain of primiparous mothers in England, and to identify potential ris k factors for maternal obesity. DESIGN: A retrospective, repeat-pregna ncy study which examined the change in maternal body weight from the b eginning of the first successful pregnancy to the beginning of the sec ond. SUBJECTS: Two hundred and forty-three mothers, all of whom had be en weighed during the first trimester of their first and second pregna ncies, and none of whom had fallen pregnant less than 12 months after the birth of their first child. MEASUREMENTS: Sociodemographic, behavi oural, medical, obstetric and perinatal data, together with antenatal measurements of maternal body weight and height, were extracted from e ach mother's obstetric notes. A comprehensive survey of weighing scale s used at all antenatal clinics was undertaken. RESULTS: After account ing for the effect of ageing, there was no significant long-term incre ase in mean maternal body weight following the first pregnancy (95% Co nfidence Intervals: -0.82-0.28 kg). While most mothers (70.8%) gained 1.0 kg or less, 24.7% gained more than 1.54 kg. Even after accounting for the maximum error in clinic scales, 14.8% of the mothers gained 1. 54 kg or more in association with their first pregnancy. Mothers with higher BMIs at the beginning of their first pregnancy, who gained more weight during pregnancy, gave birth to heavier babies and had longer intervals between their pregnancies, gained significantly more weight from one pregnancy to the next. CONCLUSIONS: pregnancy has little impa ct on the mean weight gain of primiparous women from England, who have a row prevalence of obesity (BMI greater than or equal to 26.0, 25.5% ). Nevertheless, pregnancy may be associated with a permanent increase in maternal body weight simply because it is a period of positive ene rgy balance during which some women gain excessive weight. Other facto rs, such as prepregnant BMI, determine whether long-term weight gain a ctually occurs.