I finally found the research that is behind the statement that 99%, 98%, ‘almost all women’, can breastfeed. It’s contained in a WHO report from 1989.
In the report nearly 4000 women from Nigeria and Zaire, as well as 450 from Guatemala are followed. No lactation failure is observed. You can read it at the link above.
Here’s my problems with the study in comparison to our industrial world.
Ancestral diet: In pre-industrial societies the population is more likely to be eating what they have been eating for the past several centuries. This means allergies are more likely to have worked themselves out of the population. Us in the western world? We’re eating sugars and processed flours and food additives, colors and dyes and flavors, not to mention foods our ancestors didn’t eat.
Genetic diversity: People in the USA, New Zealand, Australia, Europe, the UK and similar countries are less genetically diverse than African populations. However, this African genetic diversity is cluster or tribally based and not the hybrid mix that is found in the Western/developed world. That is, while many variations on the theme of humanity are present in Africa, they are not mixed as much as might be found elsewhere in the world. This means that while the populations are diverse, each individual population has gained genetic stability for issues like tongue tie and PCOS. Possibly to the point that these issues have been, to some degree, bred out of these populations. (See the comments as there are some important clarifications discussed there)
Chemical exposure: In industrial societies we’ve had decades of being exposed to endocrine disruptors, pesticides and industrial toxins. This means we are more subject to the things that go along with that, like endocrine disorders, autoimmune disease, and genetic mutations.
Modern medical science: We now have women surviving childbirth who may not have without modern medicine, and likely would not in a less developed country. The 2005 WHO report indicates a ‘natural’ childbirth mortality rate of 1-1.5%. This includes issues like high blood loss (a factor in lactation failure), postpartum infection (potentially as a result of retained placenta, another potential lactation issue). We also have women conceiving who may not have in the past.
The 1989 study above puts the blame on psychosocial factors for women not breastfeeding and seems to imply that all lactation failure is a result of perceived insufficiency rather than actual issues. In addition it makes the assumption about the nearly 4000 African women that secreting milk=enough milk to sustain the infant. For the Guatemalan women the 448 are over an 8 year period and apparently all living children were all successfully breastfed. I’ve mused before that the 98-99% is potentially the percentage of mothers unable to secrete milk at all. A figure that meshes well with the ‘natural’ childbirth mortality rate incidentally. Or unable to physically put the baby to the breast due to serious medical issues like postpartum cardiomyopathy.
All of these factors contribute to a higher rate in developed countries. Simply put we are not women living traditionally in Africa. The differences between the populations considered are of considerable significance. The psychosocial factor is of importance, but for those who did educate themselves, did ‘do everything right’ and still experienced issues, it is clearly not the only meaningful factor.