In developed Western nations with a strong Catholic heritage, women are less likely to breastfeed than those in countries where Protestantism predominates, concludes an observational study, published in the online journal BMJ Global Health.
Policies promoting breastfeeding should be adapted to better fit prevailing cultural and religious norms, say the researchers.
The World Health Organization (WHO) recommends that women breastfeed their babies exclusively for the first six months and then partially until the child reaches the age of 2, but rates of breastfeeding vary widely among developed nations.
In a bid to gauge this, the researchers used publicly available data to look at breastfeeding rates and the proportions of Catholics and Protestants in 135 countries and in the regional areas of five Western countries: France; Ireland; the UK; Canada; and the USA.
Central and South American countries had the highest proportion of Catholics (an average of 68%) and Sub-Saharan African countries the highest proportion of Protestants (an average of 32%).
The proportions of Catholics and Protestants varied most widely in Western countries, as did breastfeeding rates.
After taking account of influential factors, such as population density, gross domestic product (GDP) and the Human Development Index (HDI)--a composite measure of average life expectancy, educational attainment, and income per head of the population that is used to rank countries' development--the researchers found an association between religious affiliation and breastfeeding rates in Western countries.
A higher proportion of Catholics in these countries was linked to lower breastfeeding rates, an association that wasn't evident in countries in other regions. This association held true even when the researchers looked at rates in different areas of the same country.
The higher the proportion of Catholics in regions of France, Ireland, the UK and Canada, the lower were the breastfeeding rates in those regions. A similar association was seen among white women in US states after factoring in household income.
This is an observational study, so no firm conclusions can be drawn about cause and effect. Furthermore, the study reflected a snapshot in time, and observations made at the population level may not reflect the behaviour of individual women, say the researchers.
They call for further research to confirm or refute their findings. "If confirmed at the individual level, our findings may help improve current breastfeeding promotion policies," they write.
And they conclude: "Our results suggest that women living in a country or region where Catholicism has historically dominated are less likely to initiate breastfeeding, and that breastfeeding promotion policies should be adapted to better fit populations' cultural and religious norms."