Breast-Feeding and the "Missing Girls"

A new working paper by Seema Jayachandran and Ilyana Kuziemko offers another explanation for the “missing girls” phenomenon observed in some developing countries. Breast-feeding both improves health outcomes and temporarily decreases fertility. Jayachandran and Kuziemko argue that women with a preference for male children may wean daughters earlier in the hopes of restoring their fertility and conceiving a son, resulting in worse health outcomes for girls. The authors find that daughters are weaned sooner than sons and conclude that the breastfeeding factor explains 14 percent of India’s missing girls. (Related: even in the U.S., some Asian families exhibit a “son preference.”) (HT: Karen Grepin) [%comments]


While breastfeeding does improve the chance for healthy outcomes for babies, I thought that old wives' tale about breastfeeding as a contraceptive had been put to rest a long time ago.


Breastfeeding as contraceptive is not necessarily an old wives' tale. There are certain conditions which must be met - if I remember right, the baby has to get all its nourishment from breastfeeding, and has to be fed on demand - and even then it doesn't reliably work for all women, but it does work pretty well for many women.


It appears that lactational amenorrhoea method or LAM is a genuine and 98-99 per cent effective form of birth control providing that it is followed on a rigorous breastfeeding schedule coupled with monitoring other bodily signs like menstruation, body temperature and cervical mucus. It appears that the success probability falls 10 per cent when relying on the monitoring of menstruation alone. LAM appears to be advised only for when a suckling infant is 6 or fewer months of age, and supplementing with other contraception methods thereafter.

The CDC appears to keep various U.S. data of postpartum health via their PRAMS program. It seems that breastfeeding is linked in several ways to improved health depending on how long a mother does it. Among some ethnicities (caucasian especially) and age ranges (<20) there is a propensity to give up breastfeeding earlier which correlates to lower baby healthfulness.



There's a huge difference between "reduces fertility" and "contraceptive". I wouldn't use breast feeding to *prevent* pregnancy, but when you measure across a population the reduction appears.


Yes, studies have shown that exclusive breastfeeding can delay the return of menses and fertility for a few months.

This theory of the gender gap is fascinating, and one I would've never thought of. Thanks!


Education is the issue that sticks out for me here. Is it plausible that these women *know* breastfeeding can decrease fertility?

Another idea: perhaps the women weaned sooner not because they wanted to restore fertility as soon as possible, but because they were disappointed with having a girl and were averse to the "bonding" aspect of breastfeeding?


@ Kay "Is it plausible that these women *know* breastfeeding can decrease fertility?"

Of course it is plausible. I would even say it is probable.


Breastfeeding in traditional cultures is an extremely effective contraceptive, generally leading to spacing of 2 to 3 years.When babies are held by their mothers all day and sleep next to them at night, the babies nurse several times an hour for short feedings. It is this frequency that has the contraceptive effect.


...but Kay DOES have a point: I thought of the exact same thing when reading the post: I think the women were unhappy with girls and unwilling to continue breastfeeding for a long period of time.


In cultures in which breastfeeding is the normal method of infant feeding, of course women will be able to observe the contraceptive effect. Their own fertility will take months to years to return, as well as that of their peers. This can be true in cultures in which, unfortunately, breastfeeding is not the norm, but as observed by Hannah, above, it is unrestricted breastfeeding, both day and night, that results in the delayed/reduced fertility.


OK, so there is a cause, and suppose it has some evolutionary significance (i.e. it is a product of evolutionary developments in child bearing).

What are the implications of the mismatch? Increased competition for mates? A large youthful male-dominated society that is prone to war as a means of eliminating competition for territory, resources, propagation? (see Iran, China, N. Korea)

Why would a disproportionate number of males be a successful evolutionary strategy? How is a large military symptomatic of this drive? In other words, what does it mean and why should one care?

Avi Rappoport

@Kay, formal education is unnecessary, simple observation is all it takes. Most women don't get pregnant until they wean their babies. And in any village culture, or even one more communal than your average suburban area, observation is pretty much forced upon a person.


An interesting hypothesis. Breastfeeding can't be the only factor though, and I wonder if it is even a major one, because the nutritional benefits of breast milk over formula are, per recent studies, not vast, and breast-fed babies are usually a little leaner. But perhaps in the context of rural poverty it's breast milk or pretty much nothing until the baby can eat solids.

In very conservative sexist parts of North India people who are too poor for sex-selective abortion do regularly starve their little girls, and in the wealthier hospitals in big cities, there are just many more boys born because families have the money to get around bans on sex-selective abortion. I believe Rajasthan launched a program that offered money to people who had daughters to encourage them to keep their little girls and feed them well....I wonder how well that's working.


@ SP the "nutritional benefits of breast milk over formula" are, IN FACT, significant...what "recent studies" do you refer to?

I think there probably is something to the study. My inclination would not be to accuse the mothers of outright resistance to bonding by weaning earlier, but believe more that the impetus to try again would be strong.

The extended breastfeeding does work in terms of staving off fertility...I did not get a period for 20 months while breastfeeding. Women who live a rougher lifestyle and get more strenuous exercise through manual labor probably experience the effect to an even stronger degree.


"The authors find that daughters are weaned sooner than sons and conclude that the breastfeeding factor explains 14 percent of India's missing girls."

So 86% are either aborted or left to die of exposure post birth?

In considering the issue via the Pareto Principle, this 14% is not worth concentrating on if it is desired to change the trend.