In the beginning, women fed their infants exclusively on breast milk. Then came baby bottles. While bottles freed mothers from the constraints of lactation, it soon became evident that bottle-fed infants did not survive well. By the start of the 20th century in Europe, it had already dawned on child welfare agencies that it was time to go back to the beginning.
Not only does mother's milk contain substances, such as antibodies, that protect the infant from diseases, but maternal milk, plus the container it comes in, is the cleanest, most germ-free way to feed a baby.
In the pasteurized, vacuum-sealed, irradiated world of the affluent west, it is easy to forget how quickly an infant can die from diarrhea caused by contaminated food or water.
Exclusive breast-feeding is now recommended worldwide. But it's not that simple. At some point, infants must be weaned onto adult fare, and the question is, when? How long should mothers breast-feed exclusively, and when should they start introducing complementary foods? The answer can be a matter of life and death in developing countries.
On the one hand, if foods are introduced too late, then a lactating mother, undernourished to begin with, might be unable to meet the demands of her growing infant. On the other hand the sooner an infant eats or drinks something other than breast milk, the greater are its risks of getting sick from contaminated food, especially in conditions of poor sanitation.
The World Health Organization currently recommends introduction of supplementary foods between four and six months of age. Many health workers, however, feel that in developing countries, it is safer to wait until six months. Research based at UC Davis has gone far to clearing up this question.
Professor Kathryn Dewey, Roberta Cohen and Professor Ken Brown with the Department of Nutrition and the Program in International Nutrition, have studied the effects of different breast-feeding practices in a low-income community in Honduras. The researchers and their colleagues in Honduras collaborated closely with La Leche League in that country.
The subjects of one study were 141 first-time mothers from low-income neighborhoods in the city of San Pedro Sula. All these women fed their infants nothing but breast milk for the first four months. Researchers then randomly assigned the subjects to different groups: those who were asked to continue exclusive breast-feeding for two more months, and those who were given jars of pre-prepared food to supplement their infants' diets while still breast-feeding .
The scientists measured a host of outcomes, from how much breast milk infants drank (by weighing infants before and after suckling), to number of daily feeds and duration of suckling time (about 14 feeds per day, totaling some 3.5 hours for mothers of four -month olds). Infants were also weighed every month until their first birthday.
In this community, there were strong attitudes against exclusive breast-feeding beyond the first four months. In fact, many women failed to join or complete the study because of pressure from family and friends. Not only did people think that infants' growth would falter on breast milk alone, they also saw four months of age as a critical time for infants to learn how to eat adult-type food. If a mother waited longer than this, they believed, then her baby would end up a fussy eater with a poor appetite.
Contrary to these beliefs, the results of the UCD study showed that there was no advantage in introducing food before six months. The babies who received supplements at four months grew no faster during the first year of life, and both groups of infants had equal appetites for various foods by their first birthday.
Comparing these Honduran infants with a group of exclusively breast-fed babies from Davis shows breast milk to be a great leveler. While the Davis infants were born substantially heavier, the Honduran babies caught up rapidly and by three to four months, weighed about the same as their Californian counterparts.
Based on these results, the UCD team recommends that infants be exclusively breast-fed for the first six months, thereby maximizing the intake of breast milk while minimizing the risk of contamination from weaning foods.
Programs that promote exclusive breast-feeding for six months probably do more for improving infant health and survival than any number of clinics handing out antibiotics.
* This study was carried out as part of UC Davis' Program on International
Nutrition, dedicated to promoting research, training, and outreach
concerning the nutritional problems of underserved populations
in low-income countries. Additional information on the Program
can be obtained from its web site http://nutrition.ucdavis.edu/PIN
or from the Program Director.
Dept. of Anthropology, University of California, Davis, CA 95616
e-mail: kjstewart@ucdavis.edu