Impact of smoking on the duration of breastfeeding in mothers with insulin‐dependent diabetes mellitus

Abstract

The effect of smoking on breastfeeding was studied in 252 mothers with insulin-dependent diabetes mellitus (IDDM) giving birth in the period 1985-1995 and of whom 31% were classified as White group B, 16% group C, 37% group D and 16% group F or R. As part of a centralized regimen a detailed smoking history was taken during pregnancy. Forty-six percent were smokers. In 1997, a questionnaire was sent out asking for information on the duration of breastfeeding. The response rate was 87%. The duration of breastfeeding was significantly longer in the non-smoking group (p = 0.004). Fifty-five percent of non-smokers versus 33% of smokers were still breastfeeding 4 mo after birth. A strong dose-response relationship was established (p = 0.009). Cox multiple regression analysis showed a significantly negative influence of smoking (p = 0.01) and of hospitalization of the infants during the first year of life (p = 0.02) and a significantly positive influence of maternal age (p = 0.02) and birthweight (p = 0.03) on the length of breastfeeding. The breastfeeding curves for non-smokers and smokers were mainly divergent in the first month after birth, suggesting that the effect of smoking on breastfeeding is mainly exerted during that period. Smoking exerted a strong, negative, dose-dependent influence on breastfeeding duration in mothers with IDDM. Given the hazards of smoking, the advantages of breastfeeding and the possible link between being breastfed and later development of diabetes mellitus, these results should be taken into consideration when counselling pregnant women with IDDM about smoking.