Welcoming a newborn into the family is a very joyous time. However, what will this mean for the return of a woman’s fertility? It will be different for each woman. There are several factors that will determine the return speed of fertility. One of the key factors is whether a woman breastfeeds her baby or not.
Breastfeeding vs. Non-breastfeeding and Fertility
According to the American Academy of Pediatrics (APP) (1997), breast milk is the optimal form of nutrition for the baby. The APP recommends that mothers breastfeed their babies for one year. There are many benefits for the baby and the mother, but not all women can or want to breastfeed their babies.
For a woman deciding not to breastfeed her baby, fertility returns quickly, and she can get pregnant within 9-13 weeks (2.5 - 3 months) after delivery of her baby.
In North America one out of two women will choose to breastfeed. Among women who breastfeed their infants, the time from the birth of the baby until the return of regular ovulatory cycles could take months to years. Around 33% percent will have their first ovulation within the first three months postpartum, and 87% will have ovulated by 12 months. A woman who is breastfeeding may not see the presence of her period until she is completely done breastfeeding. An important factor is whether the baby was exclusively breastfed or partially breastfed (in combination with baby food).
Why the Delay?
To understand why this happens, we need to know what occurs with the hormones during breastfeeding. The hormone prolactin is the major hormone responsible for the production of milk in the breasts and also causes the suppression of ovulation. Suckling stimulates the release of prolactin. The number of times that the baby is breastfed during the day and night, and the duration of suckling by the baby will have an influence on the effectiveness and length of ovulation suppression. Levels of the luteinizing hormone (LH) are a good monitor for when ovulation is approaching and a woman’s fertility is returning almost to its optimal point. Ovulation tests can be used to start tracking this return to fertility. It's recommended to begin tracking your LH level 40 days or 6 weeks postpartum.
See the example below of a woman moving through the 4 phases, from bottom to top. (The first cycle in May includes the first two phases.)
To access this chart view in Premom app, go to your calendar and tap on "Report". For additional help, reach out to "Support'" within the app.
When to Start TTC (Trying to Conceive)
Trying to conceive while breastfeeding can be detrimental to both the recently birthed baby and newly conceived baby, so it’s best to wait at least six months before trying again. Although you can get pregnant before six months, you will increase your chance of milk dry-up and miscarriages. The rate of having a miscarriage when you start trying before six months is higher when exclusively breastfeeding (35%) than when a woman practices partial or no breastfeeding at all (14-15%).
Menstrual bleeding is the most important indicator of fertility health during breastfeeding. Begin tracking your LH level as soon as you are 40 days or 6 weeks postpartum. This will allow you to accurately predict your first ovulation and period. This will help identify when your cycles are healthy enough to start trying to conceive again and support a new pregnancy.
Download the free Premom app to track your conception and pregnancy journey!
Monica Rincon is a certified Marquette Method Natural Family Planning (NFP) Teacher / fertility awareness educator and a medical microbiologist.
- Prior JC. Chapter 15 - Postpartum Lactational Amenorrhea and Recovery of Reproductive Function and Normal Ovulatory Menstruation. In: Kovacs CS, Deal CL, editors. Maternal-Fetal and Neonatal Endocrinology: Academic Press; 2020. p. 207-14.
- Molitoris J. Breast-feeding During Pregnancy and the Risk of Miscarriage. Perspectives on Sexual and Reproductive Health. 2019;51(3):153-63.
- Ahn CH, MacLean Jr WC. Growth of the exclusively breast-fed infant. American Journal of Clinical Nutrition. 1980;33(2):183-92.
- Diaz S, Cardenas H, Brandeis A, Miranda P, Salvatierra AM, Croxatto HB. Relative contributions of anovulation and luteal phase defect to the reduced pregnancy rate of breastfeeding women. Fertility and Sterility. 1992;58(3):498-503.
- Valdés V, Labbok MH, Pugin E, Perez A. The efficacy of the lactational amenorrhea method (LAM) among working women. Contraception. 2000;62(5):217-9.
Updated August 24, 2020