BMI and duration of breast feeding.

SIR We read with interest the study by Rutishauser and Carlini which showed that, after adjusting for the effects of confounding factors, body mass index (BMI) had a significant independent effect on the rate of cessation of breast feeding. The authors further suggest that concern regarding the lack of weight loss while breast feeding may be the basis for the association found between BMI and the duration of breast feeding. W'e have recently2 examined the effect of breast feeding on postpartum maternal BMI in 9428 women who gave birth in Jerusalem. Our results support earlier observations that women who breast feed their children for long periods may tend to gain more weight. These findings also agree with reports pointing out that current recommendations for energy intake during breast feeding are higher than necessary, as the non-lactational components of maternal energy expenditure are reduced during breast feeding' and the calculated energy content of breast milk is substantially lower than that commonly reported when milk is obtained physiologically.5 A recent study" found similar six month postpartum weight loss in both breast feeding and non-breast feeding mothers despite large differences in energy intake. Brewer et al" concluded that breast feeding does play a role in postpartum weight and body fat loss, but that the current recommended allowance may be too high to permit such losses. Concern has been expressed that attitudes favouring slimness may relate to lower maternal weight gains during pregnancy and thus adversely affect fetal outcome.' However , as we,5 and others, have shown, weight gain during pregnancy may have a much smaller effect on fetal weight gain in women with a high BMI. We are therefore less concerned in obese women about the possibility that "dieting could compromise the ability to breast feed successfully".' Although more data are definitely needed, it seems that body conscious obese women could be allowed to reduce their energy intake or even choose a weight reducing diet after delivery without a substantial negative influence on prolonged breast feeding. Rutishauser and Carlin' have identified an important group at risk for early cessation of breast feeding. Careful dietary instructions and reassurance that breast fced-ing may actually aid in losing the extra body fat which has been laid down during preg-nancy9 may encourage overweight women to breast fced for longer.