Women are twice as likely as men to develop Multiple Sclerosis in their lifetime, and recent studies have been focused on discovering links, if they exist, between MS and motherhood. The relationship between women and MS has become increasingly complicated as fluctuations in risk have been identified throughout pregnancy, after giving birth, and even regarding the age of a woman at the time of the first menstruation cycle.
The American Academy of Neurology recently published an article after conducting a study that found that women who breast-feed their children for at least 15 months over one or more pregnancies may have a lower risk of developing MS. The study compared breast-feeding mothers to mothers who either did not breast-feed or only breast-fed for up to four months.
The study also included participants who had been diagnosed with clinically isolated syndrome (CIS), a precursor to MS which has been linked in previous studies to the development of MS. All in all, the study found that women who breast-feed over a total period of 15 months or longer are 53% less likely to develop MS or CIS.
Study demographics and background
Dr. Annette Langer-Gould, MD, PhD authored the study published in an online issue of Neurology. She is an active member of the American Academy of Neurology, and practices with Kaiser Permanente Southern California in Pasadena.
379 female participants were assessed using a questionnaire of relevant topics. All 397 had been diagnosed with either MS or CIS, and the average age of the women was 37. The results of the participants were compared to an additional 433 women who were healthy and who participated in the same questionnaire. Women on both sides of the study were matched for age and race with their counterpart.
The questionnaire focused on pregnancy periods, breast-feeding practices, use of hormonal contraceptives, and the length and history of ovulation. Participants answered questions in person, and since the questions involved a period of time usually earlier in life, there may be a small room for error in patient memory. Women who did not breast-feed were also not questioned as to why they did not breast-feed, or why they only breast-fed for a short amount of time.
Previous studies have shown that women already diagnosed with MS are less likely to relapse in the second to third trimester of pregnancy, which drew attention to the possibility that MS progression and significant hormonal changes in mothers may be linked. The tendency is for risk of MS relapse to increase again in the 3 to 6 months after giving birth.
The history of breast-feeding studies proves controversial, as previous attempts to understand the link between breast-feeding and MS have had both positive and negative outcomes. Dr. Langer-Gould avoids this controversy by widening the scope of her study over previous studies, and simply targeting whether or not there is a statistical advantage to breast-feeding in preventing the development MS.
Outcomes and verdict of the study
Of the women who participated in the study who had been diagnosed with MS, 44 declared that they had breast-fed for 15 months or longer. By comparison, 85 of the women who did not have MS declared that they had breast-fed for 15 months or longer—nearly two times as many. The study did not examine whether or not the 15 months was continuous, but the results suggest that continuous periods of breast-feeding are not relevant to the health benefits.
118 women who had not breast-fed at all, or who had breast-fed for less than 4 months, had been diagnosed with MS or CIS. This is compared to 110 healthy women who had also breast-fed for four months or less. The rest of the women in the study had breast-fed somewhere between 4 months 15 months, where there were no significant comparisons.
This led Dr. Langer-Gould and the study group to the conclusion that women who breast-feed for more than 15 months, no matter how consecutive the period, have a lower risk of developing of MS.
Ovulation and the risk of developing MS
Dr. Langer-Gould also directed the study towards understanding the relationship between sex hormones and the development of MS. It has been suggested by previous studies that sex hormones are partially responsible for the development of MS, but Langer-Gould wanted to explore the hypothesis that lack of ovulation had a role to play.
The survey given to the participating women included questions about the history and length of menstrual cycles, to see if ovulation offered any relevant findings to the study. The study found that women who were 15-years-old or older when they experienced their first menstruation were at a lower risk of developing MS than women who received their first period at age 11 or younger. 44 healthy women experienced menstruation at age 15 or older, compared to 27 women with MS or CIS. 131 with MS or CIS experienced menstruation at age 11 or younger, compared to 120 healthy women.
With the findings of age-related risk, the study was able to conclude that the overall years of ovulation were not a significant factor in the risk of developing MS. The average age of the participants was 37, and no correlation between years of ovulation and risk of MS could be found.
The study was also able to rule out several other factors in risk of developing MS. The age of a woman when giving birth to the first child was ruled out as a nonfactor. Number of children, following the finding that breast-feeding could yield benefits across any number of pregnancies, was also ruled out. Despite suggestions from other studies, use of hormonal contraceptives was also found to be irrelevant.
Skepticism in the study results
Specialists cautioned that the results of the study be taken with a grain of salt. The discovery of a correlation between breast-feeding and MS development does not suggest that failure to breast-feed could cause the development of MS. They instead see the study as an opportunity for mothers to be supported in deciding to breast-feed, and believe that breast-feeding should be supported in light of this and other benefits to both mother and child.
Dr. Langer-Gould cuts through any skepticism by saying that the study is simply “another example of a benefit to the mother from breast-feeding.” While the study does not shine any direct light into the origins or development of MS, it certainly suggests that the benefits of breast-feeding have yet to be fully appreciated.