Breastfeeding: Is there benefit of suppression of ovulation through nursing?

I understand that breastfeeding suppresses ovulation. I also understand that breastfeeding reduces the risk of ovarian cancer. My question is this: Is there any short or long-term health benefit to suppressed ovulation? In other words, is it the suppressed ovulation caused by breastfeeding that reduces the cancer risk? If not, is there anything that could be considered a benefit of suppressed ovulation caused by breastfeeding?


Debbi Donovan

Debbi Donovan is a Board Certified Lactation Consultant, as well as a retired La Leche League Leader. For more than a decade, Debbi... Read more

Exclusive breastfeeding (where baby receives nothing else by mouth) can suppress ovulation. It has been found that the Lactational Amenorrhea Method (LAM) of family planning, when properly used (exclusive and frequent breastfeeding along with absence of menses in first six months), is 98 percent effective in preventing pregnancy during that period of time. Many women find that continuing to breastfeed will postpone the return of fertility for a year or more.

Suppression of ovulation has be associated with health advantages for the nursing mother. A nursing mother has a decreased risk of developing not only ovarian cancer, but also premenopausal breast cancer (McTiernan, 1986), ovarian cancer (Gwinn, 1990; Schneider, 1987), endometrial cancer (Petterson, 1986), and cervical cancer (Brock, 1989).

We know that the things influencing a woman's risk of breast cancer, such as number of pregnancies, and time of the first menstrual period, are related to ovarian function. Oncologist, William C. Dooley, MD, director of the Johns Hopkins Breast Cancer Center stated that "there's a relationship between the number of menstrual cycles a woman has before her first pregnancy and breast cancer and a relationship between her total lifetime dose of estrogen and breast cancer ... What has happened in this country is that the average age of the onset of menstruation has fallen and the age of menopause has risen. And with delayed child-bearing, there's also a longer interval between the first period and the first pregnancy, and that's where the risk is. Breastfeeding decreases the risk, and having more children decreases the risk." Most likely, extended breastfeeding reduces the risk of ovarian and breast cancer because it reduces ovarian function (Intelihealth News, June 1997).

A study published in The New England Journal of Medicine stated that if women who do not breastfeed or who breastfed for less than three months would nurse for 4 to 12 months, breast cancer among premenopausal women with children could be reduced by 11 percent, and if all women with children breastfed for 2 years or longer, the incidence might be reduced by 25% (Newcomb, 1994).


  • Brock, K. E., "Sexual Reproductive, and Contraceptive Risk Factors for Carcinoma-in-Situ of the Uterine Cervix in Sidney," Med. Journal of Australia,1989
  • Byers T., et al. Lactation and breast cancer: evidence for a negative association in premenopausal women. American Journal of Epidemiology 1985; 121:664-74.
  • Gwinn, M.L. et al., "Pregnancy, Breast Feeding, and Oral Contraceptives and the Risk of Epithelial Ovarian Cancer," J Clin Epidemiol 1990; 43(6): 559 568.
  • Layde P.M., et al. The independent associations of parity, age at first full term pregnancy, and duration of breastfeeding with the risk of breast cancer. Journal of Clinical Epidemiology 1989; 42:963-73.
  • McTiernan et al. "Evidence for a Protective Effect of Lactation on Risk of Breast Cancer in Young Women," Am J Epidemiol 1986; 124(3):353-358.
  • Newcomb, P.A. et al. 1994 Lactation and a reduced risk of premenopausal breast cancer. The New England Journal of Medicine 1994; 330(2):81-87.
  • Petterson B, et al. "Menstruation span- a time limited risk factor for endometrial carcinoma". Acta Obstet Gyneocol Scand 1986; 65:247-55
  • Schneider, A. P. "Risk Factor for Ovarian Cancer." New England Jounal of Medicine, 1987.
  • Siskind V., et al. Breast cancer and breastfeeding: results from and Australian case-control study. American Journal of Epidemiology 1989;130:229-36.
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