Can you get pregnant while breastfeeding? How the breastfeeding method works, why fertility can return before your first period, and contraception that suits nursing mums

Yes, you can get pregnant while breastfeeding. KKH's obstetricians say fertility can return within weeks of giving birth, and that breastfeeding only protects you from pregnancy when three things are all true: you're fully breastfeeding, your period hasn't come back, and your baby is under six months. Doctors call this the lactational amenorrhoea method, or LAM, and KKH puts its failure rate at 1 to 2%. Once any of the three stops being true, or if you'd rather not rely on it, KKH's advice is to use contraception from the first time you have sex after the birth. Condoms, the mini pill, injections and an IUD or hormonal IUS fitted six weeks after delivery all suit breastfeeding mums; the combined pill doesn't, because it interferes with milk production.

The three conditions for breastfeeding to protect you

LAM depends on frequent feeding, day and night, so it only holds while all three conditions do.

KKH lists LAM's reliability at 98 to 99%, about the same as the mini pill, but only while all three hold. If you mostly pump, have gone back to work or are spacing out feeds, don't rely on it; ask your doctor about another method.

Why you can get pregnant before your first period

You release an egg about two weeks before a period, not after it. So the first egg after the birth can come before you've had any period at all, and a pregnancy can start with no warning. That's why KKH says you may get pregnant when you have sex unless you're fully breastfeeding, even though your body has barely recovered from the birth. Our guide to ovulation and your fertile window explains the cycle, and the bleeding you see in the first weeks after delivery is covered in our guide to postpartum bleeding.

There's no fixed date for your first period after the birth, so don't wait for it as a sign that it's time to start contraception.

Contraception that's safe while breastfeeding

KKH's O&G department lists these methods as suitable for breastfeeding mothers. Reliability figures are KKH's own.

Not suitable while breastfeeding: the combined pill, which KKH says interferes with milk production. Permanent options, tubal ligation for women or vasectomy for men, are irreversible, and KKH doesn't recommend sterilisation for women under 35 in case they want another child later. Most reversible methods wear off quickly; KKH says most women get pregnant within six months of stopping contraception.

Raise contraception at your six-week postnatal check, or earlier if you plan to have sex before then. Our guide to contraception after giving birth shows when each method can start and where to get it. Our guide to sex after giving birth covers when it's safe and what to expect.

If you think you're pregnant while breastfeeding

• Do a home pregnancy test. Breastfeeding doesn't stop a test working. Our guide on when to take a pregnancy test covers timing, and a faint line still usually means pregnant.
• Book a GP, polyclinic or your O&G to confirm it and date the pregnancy, especially if you haven't had a period, since you can't count from your last one.
• Ask your O&G whether to keep breastfeeding, and mention it at every antenatal visit.
• Think about spacing. KKH's O&G team says a longer gap gives your body time to recover and rebuild nutrients such as calcium and iron, though there's no single right answer; our family planning guide weighs the pros and cons.

For breastfeeding questions along the way, HealthHub lists the Breastfeeding Mothers' Support Group counselling line on 6339 3558 and KKH Lactation Services on 6225 5554 during office hours.

Frequently asked questions

Can you get pregnant while exclusively breastfeeding?

It's unlikely but possible. KKH puts the failure rate of the breastfeeding method at 1 to 2%, and only while you're fully breastfeeding, have no period and your baby is under six months.

Can you get pregnant before your first period after birth?

Yes. You ovulate before a period starts, so the first egg can come before any period. KKH says fertility can return within weeks of giving birth.

When does breastfeeding stop protecting against pregnancy?

As soon as your period returns, your baby turns six months, or you stop breastfeeding fully, for example with regular formula or solids. From then, use another method.

Which contraception is safe while breastfeeding?

KKH lists the hormonal IUS, copper IUD, mini pill, hormonal injections, condoms and diaphragm as suitable. The combined pill isn't, because it interferes with milk production.

How soon after giving birth can I get an IUD?

KKH lists insertion of an IUD or hormonal IUS at six weeks after delivery. Ask about it at your postnatal check.

Do pregnancy tests work while breastfeeding?

Yes. A home test detects pregnancy hormone in urine whether or not you're breastfeeding. If you get a positive, see a doctor to confirm and date the pregnancy.