Can You Get Pregnant While Breastfeeding? Fertility, Birth Control and Nursing While Pregnant

“You can’t get pregnant while you’re breastfeeding” is one of the most persistent myths in early parenthood. Breastfeeding can delay your fertility, sometimes for months, but it doesn’t switch it off reliably, and plenty of people find themselves pregnant again sooner than expected.

This guide explains how breastfeeding affects fertility, when it can work as birth control, which contraception is compatible with breastfeeding, and what to expect if you breastfeed through a new pregnancy. For more on caring for yourself while nursing, see our breastfeeding nutrition and health hub.

How breastfeeding affects your fertility

Frequent breastfeeding, especially at night, affects the hormones that trigger ovulation. That’s why many exclusively breastfeeding parents don’t have a period for months after birth.

But the timing is unpredictable, and there’s an important catch: you ovulate before your first period, not after it. So your first sign that fertility is back may be a positive pregnancy test.

Things that can bring fertility back sooner:

• longer gaps between feeds, especially a baby sleeping through the night,
• adding formula, other drinks or solid foods,
• possibly, pumping instead of some feeds at the breast, and
• your baby getting older.

For comparison, ACOG says that if you are not breastfeeding, ovulation may happen within a few weeks of childbirth, while with breastfeeding it may be delayed but usually returns by about 6 months.

The lactational amenorrhea method (LAM)

Breastfeeding can be used as temporary birth control, called the lactational amenorrhea method. According to the CDC, all three of these must be true for it to protect you:

LAM condition	What it means
1. No periods	Your menstrual periods have not returned since the birth
2. Fully or nearly fully breastfeeding	No more than 4 hours between feeds during the day or 6 hours at night
3. Baby under 6 months	LAM stops working as birth control at 6 months

As soon as any one of these changes, LAM no longer protects you, and you need another method. ACOG adds that LAM has no cost and no side effects, but it’s unclear whether pumping reduces its effectiveness. It also doesn’t protect against sexually transmitted infections.

LAM works well for some families, but many find it hard to keep to. A longer stretch of sleep, a bottle of pumped milk at daycare or a first taste of solid food can all mean the method no longer applies.

Birth control that’s compatible with breastfeeding

Plenty of options work well alongside breastfeeding. The CDC’s medical eligibility criteria guide which methods are suitable after birth:

Method	Breastfeeding notes
Condoms and other barrier methods	No effect on milk; condoms can be used any time
Copper IUD	No hormones; doesn’t affect milk
Hormonal IUD	Progestin only; generally compatible
Implant	Progestin only; generally compatible
Progestin-only pill (“mini-pill”)	Generally compatible; take at the same time each day
Injection	Progestin only; generally compatible
Combined pill, patch or ring (estrogen)	ACOG advises avoiding for the first 4 to 6 weeks if breastfeeding; very small risk to supply

For progestin-only methods, the CDC’s evidence review says studies of pills, injections and implants started within 6 weeks of birth found no detrimental effect on breastfeeding or on babies’ health, growth and development in the first year, although it describes those studies as generally of poor quality. Estrogen-containing methods add to the blood clot risk that is already higher after birth. The CDC advises against them in the first 21 days after birth, and ACOG advises breastfeeding parents to avoid them for the first 4 to 6 weeks, until breastfeeding is established. ACOG describes a very small risk that estrogen affects milk supply, and the CDC says study results on this are conflicting.

The best time to talk about birth control is before you leave the hospital or at your postpartum visit. Bring up your breastfeeding plans so your provider can match the method to them. If your supply ever drops after starting a new method, our guide on how to increase milk supply can help while you talk to your provider.

Breastfeeding while pregnant

If you do get pregnant, you don’t automatically have to wean. La Leche League International says that in a normal pregnancy there’s no evidence that continuing to breastfeed takes nutrients the unborn baby needs. It cites research that found no difference in full-term birth rates or birth weight between mothers who breastfed during pregnancy and those who didn’t (high-risk pregnancies were not included).

What about contractions? Breastfeeding releases oxytocin, but LLLI explains that the uterus responds very little to oxytocin until close to labor, and there’s no reason to link breastfeeding in a normal pregnancy with miscarriage.

Talk to your provider first if

• you’re expecting twins or more,
• you’ve had a miscarriage or preterm birth before, or are at risk of early labor,
• you have bleeding or pain, or
• you’ve been told to avoid sex or nipple stimulation during this pregnancy.

What you may notice

• Sore nipples. Tenderness is common in pregnancy. Changing positions or keeping feeds shorter can help.
• Less milk. LLLI says supply often drops around the fourth or fifth month of pregnancy, sometimes earlier, because of pregnancy hormones. Extra feeding or pumping won’t bring it back up the way it would outside pregnancy.
• Changes in taste. LLLI says the composition and flavor of your milk can change, and that this may prompt some older toddlers to nurse less often or wean entirely.
• Your nursling’s needs. If your nursing child is under 1 year, LLLI advises keeping an eye on their weight gain, since breast milk may be a big part of their diet. Our breast milk intake calculator shows typical amounts by age.

Eat well and rest when you can: you’re nourishing a pregnancy and a nursing child. Our guide to how many calories breastfeeding burns explains energy needs while nursing; your prenatal provider can help you plan for both.

Tandem nursing after the birth

Some families continue through pregnancy and then breastfeed both children, called tandem nursing. LLLI notes that nursing during pregnancy doesn’t use up the colostrum your newborn needs, and, citing lactation author Nancy Mohrbacher, suggests giving the newborn first priority at the breast in the early days so they get the nutrients and antibodies in colostrum.

Tandem nursing may also help with engorgement in the early days, and your supply adjusts to demand. Your older child may want to nurse more often at first; gentle limits, such as waiting until the baby has finished, often help.

If you’d rather stop, our guide on how to stop breastfeeding explains how to wean gently, during pregnancy or after.

When to talk to a doctor or lactation consultant

See your doctor or midwife if:

• you think you might be pregnant, or have spotting or pain,
• you’re breastfeeding and want to choose a birth control method,
• you have cramping, bleeding or contractions while nursing during pregnancy, or
• your nursing baby under 1 year isn’t gaining weight well.

A lactation consultant (IBCLC) can help with sore nipples, a drop in supply or planning for tandem nursing. Our breastfeeding support page explains where to find one.