When it comes to feeding infants, medicine has long held the position that breast milk is best. It has been demonstrated that breastfed babies have less diarrhea, fewer ear infections, and fewer incidents of wheezing early in life. Now, new studies suggest that children of asthmatic mothers may not receive the same benefits as children of non-asthmatic mothers. "Longer breastfeeding in infancy is associated with improved lung function in later childhood, with minimal effects on airflow in children of non-asthmatic mothers. However, longer breastfeeding in children of mothers with asthma demonstrates no improved lung growth and significant decrease in airflows later in life," said Theresa W. Guilbert, the lead author of the current study.
The results of this study are published in the latest edition of the American Journal of Respiratory and Critical Care Medicine. The study started with a population of 1,246 infants who were enrolled at birth. 679 of the original participants went on on to have lung function tests performed between the ages of 11 and 16, and the researchers obtained detailed information about whether or not they were breastfed as babies. It was found that the group of children who were breastfed had a lower lung capacity then those who were fed formula. Further analysis showed that children of non-asthmatic mothers who were breastfed demonstrated an increase in lung volume and no decrease in their air flows; this group could not account for the overall decrease. The children of asthmatic mothers who breastfed, on the other hand, showed a "significant reduction in airflows."
Dr. Guilbert speculates, based on these findings, that non-asthmatic mothers' breast milk may contain certain chemicals that promote lung development that are not present in asthmatic women. One compound that is singled out is cytokine TGF-α1—previous studies have shown infant lung wheeze is inversely proportional to the dose of TGF-α1 received in breast milk. Even though the study revealed an association between breastfeeding by asthmatic mothers and decreased airflow in the child's lungs, Dr. Guilbert cautions that the clinical implications are not yet known. "Human milk is uniquely suited to the feeding of infants, having been subject to selective pressures for millennia. It is premature to suggest any change in breastfeeding recommendations based on one study, particularly given the multiple well-documented benefits of breastfeeding," she says.
Another breastfeeding related study made public this week examined the effects of breastfeeding on the mother's breasts themselves. University of Kentucky plastic surgeon Dr. Brian Rinker said that many patients had come to his office for a breast lift or breast augmentation asking to "to fix what breastfeeding did to my breasts." Given the prevalence of cases such as this, he sought to find if breast ptosis (medical term for sagging of the breasts) was a direct result of breastfeeding. Dr. Rinker and colleagues interviewed 132 women who sought breast lifts or augmentations. They examined each patient's medical history, body mass index, pre-pregnancy bra cup size, and smoking status. What they found was that the degree of breast ptosis was no different in women who breastfed compared to those who did not. They did find that the degree of ptosis was related to age, the number of pregnancies, and whether or not a patient smoked. "Smoking breaks down a protein in the skin called elastin, which gives youthful skin its elastic appearance and supports the breast... so it would make sense that it would have an adverse effect on the breasts," Rinker concluded. This work is not yet published in a medical journal, but was presented at the American Society of Plastic Surgeons conference.
American Journal of Respiratory and Critical Care Medicine, 2007. DOI: 10.1164/rccm.200610-1507OC