This week, Dr. Sydney Spiesel discusses a new and rigorous study on the impact of breast-feeding, physical and psychological; the effect of bad marriages on the health of the heart; and a paradoxical finding about cod-liver oil.
Breast-feeding: How good for babies is it really?
Question: How do you establish the benefits of breast-feeding in a scientific way? It would be unethical—and, of course, impossible—to assign mothers randomly to either breast-feed their infants, say exclusively for six months, or to give them formula. But the differences between mothers who breast-feed exclusively and mothers who don't include socioeconomic status, degree of education, employment, ethnicity, and a host of other factors. And so without running a randomized trial, it's extremely difficult to know what's causing any perceived difference between the two groups of babies. Is it the feeding choice or some other difference in the mothers that plays the central role?
New study: Despite the obstacles, one research team headed by Dr. Michael Kramer of McGill University in Montreal has devised a rigorous approach. Instead of randomly assigning individual women to breast-feed or formula feed, this research group promoted breast-feeding in some arbitrarily chosen geographic areas around maternity hospitals in Belarus, leading to much higher rates and duration of breast-feeding. The authors then compared the women and babies from these areas with women and babies in areas where maternity centers just continued whatever had been their customary practice, having isolated the effect of an increased breast-feeding rate.
Physical findings: Dr. Kramer's group previously found some medical benefit to breast-feeding, though less than I expected. (As I have said before, I am a proponent of breast-feeding.) Increased breast-feeding reduced the rate at which babies developed diarrhea or eczema but, contrary to expectations, had little or no effect on respiratory disease.
Psychological findings: The recently reported bigger surprise, however, was that increased breast-feeding appeared to make no difference on the psychological front for babies or mothers. About 14,000 children, from the two groups, were examined when they were 6½ years old for problems with conduct, hyperactivity, and peer relations. The researchers also looked at mothers' satisfaction with their marriages and in their relationships with their children. To my amazement, the study turned up no differences in any of these outcomes. I was sure that, on average, the tactile nature of breast-feeding would promote mother-child closeness, which would mean better adjustment for the child and greater satisfaction for the mother. I was wrong.
Conclusion: Which puts me in a very awkward position. Breast-feeding is a topic that evokes strong feelings, and merely presenting facts that might be taken as not fully supportive makes some people angry. Very angry. Breast-feeding is clearly critical—and even life-saving—in parts of the world that lack sanitation and access to fresh water and refrigeration. I continue to believe that there is a biological benefit to breast-feeding even in the developed world, where the risks of formula feeding are fewer. But I am now less sure of the psychological benefit to mother or child. Finally, I still believe that the baby will prosper most if the mother's choice of feeding method is the one that gives her the most satisfaction and pleasure. But now I want that question to be scientifically studied, also.
Marital bliss: Does it make the heart healthier?
Question: Epidemiologic research has shown that social relationships can protect adults from risk of illness and death, and that marriage is particularly beneficial. But what about bad marriages? Is it better to be single than to be in one?
New study: Recent research begins to shed light on this long-ignored question. Dr. Julianne Holt-Lunstad and colleagues used blood pressure as a marker for cardiovascular risk and studied about 300 adults who responded to an ad. Two-thirds of them were married and one-third were single. Blood pressure, measured frequently over a 24-hour day, was used as a rough index of cardiovascular health.