Do you know how breastfeeding affects your fertility?

Can you get pregnant while you’re breastfeeding? When will your period come back? Can you use birth control when you’re a breastfeeding mom? Is it ok to breastfeed while you’re pregnant? These are things a mama wants to know! Here’s what the experts have to say about breastfeeding and fertility, plus some tips from real moms.

  1. Is breastfeeding a form of birth control?

Breastfeeding is about 98% effective at preventing pregnancy if all the following are true:

  • your baby is under six months old
  • your periods have not returned
  • your baby is breastfeeding regularly both night and day—no longer than every four hours during the day and every six hours at night
  • your baby only gets breast milk or tiny amounts of other food

This approach is called the Lactational Amenorrhea Method (LAM). Breastfeeding suppresses the hormones needed to trigger ovulation. (Pumping breast milk isn’t enough to suppress these hormones however.) “There is a natural child spacing that happens with exclusive breastfeeding,” confirms Joy Frazer, International Board Certified Lactation Consultant (IBCLC), RM, ND, RN, who runs her practice Joy of Life in Durango, Colorado. “For one to two women out of a hundred, though, that isn’t the case. You can ovulate in the cycle just before your period comes back, and it’s really hard to detect that first ovulation.” After all, we all know a coworker/cousin/friend whose kids are born less than 14 months apart.

45: the percentage of unintended pregnancies in the United States in 2011 source: The New England Journal of Medicine

The New England Journal of Medicine

You may have heard about “ecological breastfeeding” too, which delays the return of fertility beyond six months, although it’s not an exact science and will vary from mom to mom. In addition to frequent, regular nursing, ecological breastfeeding means you offer your breast to soothe your baby (not just for milk), you don’t use bottles or pacifiers, you co-sleep, you nap with your baby during the day and you keep your baby close to you almost all the time. “When your baby starts to crawl and cries after a bump, even a three-minute suckle can be enough to control hormone levels,” says Sara Chana Silverstein an IBCLC and classical homeopath in New York City. “It doesn’t have to be 20 minutes.” According to La Leche League, if you practice ecological breastfeeding, you have a six percent change of getting pregnant at six to 12 months post partum if your period has not yet returned.

  1. When will my period come back?

“It’s so different for every woman,” says Frazer. “Most breastfeeding women have six to 12 months before their period returns, but for some it can be up to two years.” Silverstein adds, “I’m the mom of seven so I was either pregnant or breastfeeding for 20 years straight! I nursed on demand until they were two or three years old, and I had maybe two or three periods during that entire time.”

  1. Is it safe to use birth control while breastfeeding?

Medical experts agree that it’s totally fine to use birth control while you’re breastfeeding, although it’s recommended to avoid hormonal birth control for about six weeks after your baby is born to reduce the risk of developing blood clots. Some anecdotal evidence suggests hormonal birth control could affect milk supply in the early weeks of breastfeeding. However, a 2015 study published in the medical journal Contraception looked at 47 studies that examined the use of progesterone-only contraception (for example, the “mini pill” or a levonorgestrel IUD) and didn’t find evidence of negative effects on breastfeeding. Check with your health care provider. 

Your breastfeeding and postpartum birth control chart
Centre for Disease Control (Society of Obstetricians and Gynaecologists of Canada)

  1. Can I still breastfeed my toddler if I want to get pregnant again?

Most women don’t have trouble getting pregnant while nursing a toddler if their periods are regular, says Frazer. However, every woman’s body chemistry is different. “Some breastfeeding women have suppressed estrogen levels and won’t get pregnant; some will be breastfeeding and will get pregnant,” says Silverstein. “Sometimes clients call me and say, ‘my breasts are sore while I nurse and I don’t know why’ and I say, ‘take a pregnancy test and call me back!’”

Alexis Sassard, who lives near Houston, Texas, and blogs at General Public Goods, tried for a year and a half to get pregnant again while still breastfeeding her toddler daughter Luella. So, she changed things up. “I continued to nurse her frequently throughout the day but started to get my husband involved in the evenings. I would send her off with him after a good nursing session so he could bathe her and then rock her straight to sleep,” she says. “This meant she was going anywhere from eight to 10 hours without breastfeeding. Within a couple of weeks of this new routine, I was finally pregnant again.”

A Harvard researcher suggests that 6- to 12-month-old babies that cry at night could have an evolutionary edge.

Science News
Evolution, Medicine and Public Health

  1. Can I breastfeed when I’m pregnant?

It’s safe to breastfeed while you’re pregnant. Breastfeeding can cause your uterus to contract, so if you have a history of preterm labour or miscarriages your doctor may advise against it, but generally there is no problem. Some moms enjoy the continued bond of breastfeeding while pregnant and then tandem breastfeeding afterwards (nursing both a baby and a toddler). “You may have a dip in milk supply in the first trimester, which usually rebounds in the second trimester,” says Frazer.


Other mamas find breastfeeding uncomfortable because of the sore breasts, morning sickness and fatigue that often come with pregnancy. “Toddlers may self-wean while you’re pregnant because the milk tastes different,” notes Frazer. “Moms tell me their toddlers say, “it’s yucky now!’” Silverstein encourages her clients to continue nursing until six or seven months into their pregnancy if they wish. “After that, I find toddlers can get jealous or angry about the baby. Stopping before the baby is born gives a toddler a chance to establish a different relationship with mom.” Like just about everything about parenthood, you’ll have to decide what makes sense for you and your family.


If you continue breastfeeding while you’re pregnant, your breast milk changes sometime between the fourth and eighth month. 

Pediatric Clinics
Breastfeeding Place


For Rachel Coley, a mom of two who blogs at Can Do Kiddo, breastfeeding throughout her pregnancy was right choice for her. Her baby was eight months old when she got pregnant again and she wanted to continue breastfeeding until he was at least a year old. “Even before I had a big baby belly, my abdomen got tender and I got uncomfortable with a wiggly toddler on my lap,” she says. “My go-to position was lying down to nurse. We transitioned our son to a toddler bed at 12 months and a queen-sized mattress on the floor at 15 months. This allowed me to nurse in his bed at nap times and wake-up.” Because she had some nipple soreness, she says she set boundaries. “Nursing stopped if he got too wiggly. I started singing a song as his cue that nursing was almost over and then I’d gently use my finger to break suction and pop him off when the song was all done.”

So there you go, mamas: the breastfeeding mom’s guide to fertility!