Breastfeeding has an effect on mothers' fertility, something that in turn appears to be affected by the living conditions of the mother and her newborn, a recent study shows.
The period of infertility following childbirth is lengthened when the mother is breastfeeding. While it lasts just a few weeks for a woman who does not breastfeed, it can last over several months -- even more than a year -- for a woman who breastfeeds her child. The duration of this contraceptive effect from breastfeeding is not the same in all women, and could depend on the mother's living standards, according to researchers from the Max Planck Institute for Demographic Research in Germany and the CNRS in France, published in the journal PNAS . According to their findings, mothers living in developed countries appear to have shorter periods of infertility than those living in more precarious conditions.
Breastfeeding can burn up to 500 calories a day
Producing milk requires a lot of energy from the mother: about 500 kilocalories per day, in fact, when the child receives no other food. Conceiving a child also draws considerably on mothers' reserves. It's therefore plain to see the interest of a period of infertility following each birth, preventing the onset of a new pregnancy that could endanger the mother and her children.
So if living conditions improve, does that mean that fertility returns sooner? Nicolas Todd and Mathias Lerch analyzed 2.7 million births in 84 developing countries over the past 45 years. They based their analysis on the most visible sign of suppressed ovarian function after birth, the absence of menstruation, known as postpartum amenorrhea.
The researchers found that this period of time, marked by the absence of menstruation, has significantly shortened over the years in some of the countries studied. "In Bangladesh for example, the duration of breastfeeding has remained stable, whereas the duration of amenorrhea has halved, from 11 months to around seven months," explains Nicolas Todd.
Much of this appears to be explained by rapid socioeconomic development. Indeed, the Human Development Index or other measures of development, such as access to electricity, were associated with a reduced contraceptive effect of breastfeeding. "This means that for the same duration of breastfeeding, the more developed the country, the lower the period of temporary sterility following childbirth," the study reports.