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Can breastfeeding really prevent pregnancy?

Having a baby is an exciting and life changing event. Still, caring for infants takes a lot of time and energy, especially if you’re juggling family and work. So even the happiest and proudest parents can wait a little after the birth of a child before welcoming another.

You may have heard that if you breastfeed, you won’t get pregnant. However, that’s not the whole story. The effectiveness of breastfeeding as a form of contraception depends on several factors.

What to consider if you choose breastfeeding for birth control

Experts recommend wait 18 months or more between pregnancies. This gives the uterus time to heal and is safer for the birthing parent and the baby.

There are many birth control options. Some alter the hormonal cycles that govern menstruation and pregnancy. Non-hormonal options most often block or slow down sperm, or prevent sperm and egg from meeting.

Breastfeeding is a natural birth control option that appeals to many people. Research shows that this can be an effective method during the months when a woman breastfeeds frequently and an infant receives only breast milk as food – no formula, baby food or other foods.

The medical term for this method is the lactational amenorrhea method, or LAM. Breastfeeding refers to breastfeeding and amenorrhea means not having a period or a regular menstrual cycle.

How does this method work?

Breastfeeding a baby regularly helps prevent ovulation, which is the release of an egg from the ovary. Ovulation must occur to conceive a pregnancy.

To successfully prevent pregnancy, all these guidelines must be followed:

  • Your baby is less than 6 months old and is only breastfed (no formula or food).
  • You breastfeed at least every four hours during the day and every six hours at night.
  • You are currently without menstruation (amenorrhea).

How effective is LAM?

Studies show that when used correctly as explained above, LAM can be about as effective as hormonal methods like the birth control pill. It is 98% effective within the first six months after the baby is born. This means that only two out of 100 people will get pregnant using this method if the guidelines are followed correctly. Otherwise, pregnancy is much more likely to occur. Your medical team can help you decide if this is a good method of birth control for you at this time and explain additional options to you.

What are the advantages of this method?

This form of birth control is completely natural and has no potential health risks or side effects. It is also free and does not require an appointment or medical procedure.

What are the disadvantages of this method?

  • This is not practical or possible for everyone.
  • You must be able and willing to exclusively breastfeed your newborn. Giving your baby any amount of formula or other foods decreases the effectiveness of this method of birth control. It is also unclear whether expressing breastmilk has the same effect as breastfeeding in preventing ovulation.
  • It is temporary. Pediatricians recommend starting babies on certain solid foods around 6 months of age. Babies will also start to sleep longer at night.
  • If you get your period using this method, you are likely to ovulate again. This means that you are not well protected against pregnancy and could get pregnant unless you start using another type of birth control.

If you decide to use LAM, be prepared to switch to another birth control method by the time your baby is 6 months old, or sooner if you find it inconvenient.

Is this method suitable for you?

This method might be a good choice temporarily if you are willing and able to

  • breastfeed your baby exclusively for the first six months after birth – without mixing formula or other foods
  • nurse at least every four hours during the day and every six hours at night.

This method does not protect against sexually transmitted infections (STIs), such as chlamydia or HIV. Not a good choice for anyone who wants to use a combination of breastmilk and formula, or who has a medical condition or uses medications that could harm a baby if they spread or pass through breastmilk .

Choosing the right contraceptive for you

Birth control should suit your lifestyle and meet your health needs. Some people want to avoid methods that contain hormones, for example. People with a history of blood clots or high blood pressure should avoid methods that contain estrogen. Busy people are better off using a long-term method of birth control, such as an IUD or implant. And anyone who wants to protect themselves against STIs should consider using condoms with any birth control option they choose.

Share your preferences and needs with your midwife, doctor or other members of your medical team. They can explain the options to you and help you make a decision that’s right for you.

See Harvard Health’s Birth Control Center for more information on options.

As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of the last revision or update of all articles. Nothing on this site, regardless of date, should ever be used as a substitute for direct medical advice from your physician or other qualified clinician.

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