Breastfeeding Papers

Are Lactating Women a Risk Group for Iron Deficiency Anemia?

Ted Greiner, PhD

Breastfeeding protects from anemia one of the highest risk groups--an interesting example of a win-win situation in nature. Revised from a paper presented to The First National Workshop on Nutritional Anemia
Dar es Salaam, Tanzania - July 1-5, 1991

Iron deficiency anemia is commonly stated to be a disease
of pregnant and lactating women. Such statements are misleading on two counts.

First, a large proportion of women in many developing countries are either pregnant or lactating during most of their reproductive years, and thus should hardly be considered as outside of the risk groups at any time during their fertile years. This is reflected in the overall prevalence rates for anemia in both developed and developing countries according to DeMaeyer, et al (1989) as given in the table below:

Table 1. Estimated prevalence (in per cent) of anemia in 1980

Using similar reasoning, a high proportion of lactating women are certainly anemic in most countries, especially poor ones. Thus it is correct to include them along with all other women of reproductive age among the groups to be targeted for intervention.

Nevertheless, the second misleading aspect of the statement "anemia is a disease of pregnant and lactating women" is that it implies that pregnancy and lactation are part of the cause of anemia. While this is clearly true for pregnancy, especially when birth spacing is short, the opposite is true for lactation.

Breastfeeding reduces the risk of developing iron deficiency anemia, particularly for those women who are most at risk of developing it.

This point is seldom if ever made in the literature on nutritional anemia or in papers listing the benefits of breastfeeding. (In fact, the benefits of breastfeeding to maternal health are rarely given much attention--usually lactation is vaguely assumed to be a burden on a woman's health.) Yet this benefit is easily demonstrated from a review of the data provided by De Maeyer.

DeMaeyer et al estimate that basal iron loss for a women of average body size is 0.8 mg/day. They point out that several studies (from several ethnic groups) have found that menstrual blood loss varies relatively little from month to month for any individual woman, but varies widely from one woman to another. This variation is also highly skewed. The median blood loss from each menstrual period is about 25-30 ml. Spread over a 28 day period, this results in a median iron loss of 0.4 mg/day. But 2.5% of women (+2 SD) lose iron at four times this rate, an average of 1.6 mg/day.

DeMaeyer et al state that the average amount of iron secreted into breast milk is 0.3 mg/day during the first six months of lactation and this low level is apparently universal--it cannot be increased by supplementing the lactating woman with iron. This 0.3 mg/day iron loss due to breastfeeding would decline whenever other foods replace breast milk. In the early months of life, any food or fluid may replace breast milk, especially if given in large quantity. But at 4-6 months of life the infant requires more calories than breast milk can provide for optimal growth. At this age complementation can take place without replacing breast milk if additional food is given as a "topping up" when the baby is still hungry after a breast feed.

If this pattern of full breastfeeding is followed, postpartum amenhorrea will be sustained for many months. The more intense and the longer a woman breast feeds, the longer this lactation amenorrhea will last. The other major cause of variability in the length of postpartum amenorrhea, is maternal undernutrition, though the effect is not great until undernutrition becomes severe (Short, 1984; Consensus Statement, 1988). The more undernourished the mother, the longer her period of lactation amenorrhea lasts.

At the median level of menstrual blood loss, a women might lose about as much iron in breast milk as she saved from lactation amenorrhea, for example if she breast fed for a year and had nine months' amenorrhea. However, for the women who lose the greatest amount of blood per menstrual period, breastfeeding will reduce overall iron losses. For example, for the 2.5% of women who lose 1.6 mg/day of iron from menstuation, six months of full breastfeeding would "cost" 54 mg of iron, but 48 mg of this would already be "saved" by the first extra menstrual period skipped. One year of breastfeeding that led to nine months' amenorrhea would result in an overall savings of 324 mg of iron. And it is these women with high menstrual blood losses who are most at risk of developing iron deficiency anemia in the first place.

Some might complain that it is misleading to say, based on the above argument, that breastfeeding reduces anemia risk for women, since many women introduce supplements early, often bottle feeding at the same time as breastfeeding, and thus will not have a very long period of lactation amenorrhea.

But actually this only strengthens my argument. It is bottle feeding or a lack of full breastfeeding that deprives such women from the protection they would otherwise have enjoyed from breastfeeding.

References

Consensus statement, 1988. Breastfeeding as a family planning method. Lancet 2:1204-1205.

DeMaeyer E, et al, 1989. Preventing and controlling iron deficiency anaemia through primary health care. A guide for health administors and programme managers. WHO: Geneva.

Short RV, 1984. Breast-feeding. Scientific American 250:23-29.