Breast-feeding for 15 months or longer may prevent mothers from developing multiple sclerosis at a later point. The team warns that correlation does not imply causation, but they encourage breast-feeding as a good practice.
Data made available through the Center for Disease Control and Prevention's (CDC) 2016 Breastfeeding Report Card show that breast-feeding rates in the United States are on the rise.
Fortunately, MS relapses have been found to decrease in the second and third trimesters of pregnancy, though it is said that they tend to increase again in the first 3 to 6 months postpartum.
Breast-feeding has been linked both to a risk of relapse and a drop in MS relapses, making it a controversial topic over time. A new study by Dr. Annette Langer-Gould, from Kaiser Permanente Southern California in Pasadena, looks at whether or not breast-feeding can protect new mothers from developing MS.
The findings were recently reported in the online issue of Neurology.
Breast-feeding mothers at lower MS risk
The study recruited 397 female participants who had recently been diagnosed with MS or with clinically isolated syndrome (CIS), which can eventually evolve into MS. The average age of the women in the group was 37.
The results for this group were compared with the outcomes of a group of 433 women who did not have MS. The healthy women were matched for race and age with their counterparts.
All the women were assessed using questionnaires targeting relevant topics, such as information about their pregnancy period, breast-feeding practices, and use of contraceptives.
It was found that women who had breast-fed over a cumulative period of 15 months or longer, either following one pregnancy or across several pregnancies, had the lowest risk of developing MS. They were at a 53 percent lower risk of developing MS or CIS than women who had not breast-fed, or who had breast-fed for 4 months or under.
Eighty-five of the healthy female respondents and 44 respondents with MS or CIS declared that they had breast-fed for 15 months or longer. Out of the women with MS, 118 had not breast-fed at all, or had breast-fed for up to 4 months. In contrast, 110 healthy women declared they had breast-fed between 0 and 4 months.
The researchers also investigated the lengths and histories of the women's menstrual cycles to see if ovulation held any relevance in the study outcomes.
"Many experts have suggested that the levels of sex hormones are responsible for these findings, but we hypothesized that the lack of ovulation may play a role, so we wanted to see if having a longer time of breast-feeding or fewer total years when a woman is ovulating could be associated with the risk of MS," says Dr. Langer-Gould.
Years of ovulation not linked to MS risk
It was found that women aged 15 or older when their first menstruation occurred were at a 44 percent lower risk of MS and CIS than women who had got their first period at age 11 or earlier.
Out of the participants, 44 healthy women and 27 women with MS or CIS declared that they experienced their first menstruation at age 15 or later. A total of 131 women with MS or CIS said that they were age 11 or younger at the time of their first menstrual cycle, and 120 healthy women declared the same.
These findings suggest that the number of years that the participants ovulated did not influence the risk of developing MS. Other related factors, such as age at first birth, the number of children, and the use of hormonal contraceptives, were also found to be irrelevant.
Despite discovering a correlation between breast-feeding for a long cumulative period of time and a decreased risk of MS, the specialists strongly warn against making any hasty conjectures. The correlation does not imply causation, they insist.
They do, nonetheless, view their findings as a sign that breast-feeding should be encouraged, and that mothers who wish to breast-feed should be supported to do so.
"This is another example of a benefit to the mother from breast-feeding," says Dr. Langer-Gould.
It should be noted that the research had its limitations, mainly the subjective component of the in-person questionnaires. The participants had to recall information sometimes spanning several years, so there is no guarantee that they remembered it correctly. Also, women's reasons for not breast-feeding, or for breast-feeding only for a limited period, were not looked into.