Does Breastfeeding Delay Menopause?

Most women reach menopause between 40 and 58, with the average age being 51 years old. Besides genetics — that is, when your mother experienced her last period — there are many unknowns about why some women go through this transition years earlier than others.

Breastfeeding, Pregnancy, May Reduce Risk for Early Menopause

New research suggests that motherhood — specifically, having a least one pregnancy and breastfeeding — is associated with a lower risk for reaching menopause before age 45. The study, published on January 22, 2020, in JAMA Network Open, followed 108,887 premenopausal women ages 25 to 42 from 1989 until 2015, making it the largest study examining the association of reproductive factors with early menopause.

“We found both pregnancy and breastfeeding to be independently associated with the onset of menopause,” says lead author Christine R. Langton, MPH, master of social work and doctoral candidate at the University of Massachusetts in Amherst. “In our statistical models, when we combined both those factors together, we observed the lowest risk for early menopause,” says Langton.

Defining Menopause and the Menopausal Transition

Menopause is a retrospective diagnosis usually made after a woman goes 12 consecutive months without a monthly period. The months or years leading up to that milestone is called the menopause transition, or perimenopause, and symptoms can include hot flashes, mood changes, disruptions in sleep, and changes in the monthly cycle.

Researchers conducted their investigation within the ongoing Nurses’ Health Study 2 cohort. At the start of the study, women provided their medical history and health-related behaviors, like smoking, physical activity, use of oral contraceptives, and menstrual and pregnancy status. Every two years for the duration of the study, participants updated health information, including any new health conditions or changes in health behaviors.

Women were also asked to report pregnancies, pregnancies lasting longer than six months, and births. Investigators measured breastfeeding history by asking participants if they breastfed, for how long, as well as when they began to supplement or replace breastfeeding with formula or cow's milk.

Early Menopause: Reaching Natural Menopause Before Age 45

Women’s menopause status was self-reported as well, using questions about the cause, whether the transition was influenced by health factors (cancer, surgery, or other treatment), or hormone therapy. Researchers controlled for factors like smoking, body mass index (BMI), alcohol intake, and oral contraceptive use. Reaching natural menopause before the age of 45 was considered early menopause.

When compared with women who had no full-term pregnancies, women who gave birth had a reduced risk of early menopause. Women with three pregnancies had a 22 percent lower risk, those with two pregnancies had a 16 percent lower risk, and women with one birth had an 8 percent lower risk.
Regardless of the number of children, months of exclusively breastfeeding was associated with a reduced risk of early menopause. One to six months brought a 5 percent reduced risk, seven months to a year was linked to a 28 percent risk, and 13 to 18 months was associated with a 20 percent reduced risk.
Women with three or more pregnancies who breastfed exclusively for a total of 7 to 12 months had about a 32 percent lower risk of early menopause compared with women with the same number of children who breastfed exclusively for less than one month.

Investigating Why Women Reach Menopause at the Age They Do

This study further explores the question of why women go through menopause at a particular time, says Lauren Streicher, MD, medical director of the Northwestern Medicine Center for Sexual Medicine and Menopause in Chicago.

Menopause Occurs After Ovaries Stop Producing Estrogen

What causes things to shut down so that their ovaries are no longer producing estrogen? Dr. Streicher asks. “A lot people think it’s when you run out eggs. This isn’t going to happen — we’re born with millions and millions of eggs — it’s really about the aging of eggs and what causes them to age more quickly,” she says.

If someone has pregnancy or if someone is breastfeeding, is this going to delay the aging of the eggs? “On the basis of this observational data, this research would suggest that this is the case,” says Streicher.

The numbers in the prospective study are meaningful and it appears that there is an association between women who breastfeed and have pregnancies, that they tend to go through a later menopause, says Streicher. “But do we know why that’s the case? No,” she adds.

How Women’s Bodies Slow or Delay Egg Depletion

The authors hypothesize in their findings that exclusive breastfeeding would be more strongly associated with reduced risk of early menopause because it’s more likely to suppress ovulation and “thus slow the depletion of the ovarian pool.”

What About Hormonal Birth Control Pills?

Streicher has questions about this conjecture by the authors. “Take a woman who is on birth control pills as an example; If you’re talking about things that are going to give your ovaries a rest, pregnancy and breastfeeding would fall into that category, but so would birth control pills,” says Streicher.

“When you’re on birth control pills, your ovaries are in resting mode, but women who are on birth control pills haven’t been shown to go through menopause any later,” she says. "The whole concept that that you’re going to give your ovaries a rest by breastfeeding and pregnancy and that’s somehow going to “protect” them to me doesn’t necessary make sense from a scientific perspective," she adds.

“The takeaway from this research is that, based on the findings, it does appear that women who breastfed and had pregnancies tended to go through menopause a little bit later, but we’re still not sure why that is,” says Streicher.

Why Menopause Timing Matters

When we look at the things that are the greatest determinants for when someone is going to go through menopause, genetics seems to be the one of the most important things, according to Streicher. “There’s a lot of truth in that you may follow what happened with your mother, if she went through menopause late, you may, too,” she says.

Certain medical conditions, such as autoimmune problems, thyroid issues, and lupus, can make a woman go through menopause earlier, as well as smoking, adds Streicher.

Correcting Myths About Menopause, Age, and Estrogen

A valuable aspect of this research is that it increases awareness that many women go through menopause earlier than people think, she says. “Many people don’t know that going through menopause any time after the age of 40 is considered normal. Between 40 and 45 is normal, it’s just early,” she says.

Whenever It Arrives, Menopause Comes With Health Risks

This is important because estrogen offers protective health effects and there are real health risks for women who go through menopause early, “They have increased risk for cardiovascular disease, diabetes, and cancer,” says Streicher.

“My goal as a menopause expert is that we get those women in our hands earlier. Here at the Northwestern Medicine Center for Sexual Medicine and Menopause we see very young women who have gone through natural menopause early or as a consequence of cancer or another health condition, and our goal is to make sure they don’t have those increased risks.”

When You Hit Menopause, and Lose Protective Estrogen, Prioritizing Health Is Key

“The value of research like this is not necessarily to help us figure out a way to delay menopause, but rather to increase awareness about when menopause generally occurs and what women can do to maximize their health after that transition,” says Streicher.