Possible to get pregnant while breastfeeding?

Dear Alice,

Is it possible to get pregnant when I am a lactating mother of a three month old baby and I missed my period this month? Last month, I had spotting — like I have periods for two days for the first week and second week of the month. I’m worried about getting pregnant again. Please help me; we had sex two days after my spotting/period.

Dear Reader,

Trying to make sense of an erratic menstrual cycle can certainly be confusing, especially when your hormones are going haywire after recently having a baby. To get straight to the heart of your question, the answer is yes; it is possible to get pregnant within a few months after having a baby — even if you’re still lactating. You may have heard about something called “lactational amenorrhea,” or the breastfeeding method, which is a birth control method frequently practiced by new moms. It works because breastfeeding causes a woman to stop ovulating and in turn, stop menstruating for about six months after giving birth. However, this contraception strategy only prevents pregnancy when under specific circumstances (more on that in a bit). This means that some new moms might still be at risk of pregnancy depending on their particular breastfeeding situation.

How does this whole breastfeeding method of birth control even work? The key is that when a woman is breastfeeding, the action of the baby suckling at her breast is a cue for the mom’s body to stop the release of a hormone known as gonadotropin-releasing hormone (GnRH), which regulates the menstrual cycle. This frequent suckling of a baby increases the levels of prolactin in a woman’s body — the hormone responsible for producing and releasing milk — and those high prolactin levels interfere with the release of GnRH. So, by stopping GnRH in its tracks, breastfeeding is able to prevent the whole cascade of other hormones that lead to ovulation and fertility. But here’s the kicker: just expressing milk with a breast pump or lactating (but not breastfeeding) might not be sufficient to cue the body to stop fertility. Breastfeeding only works as a contraception method if all three of these criteria are met:

  • Exclusive breastfeeding: The suckling action of the baby is believed to be the real key to preventing fertility. Some women are unable to breastfeed exclusively for any number of health or lifestyle reasons, and if the baby is getting formula or other foods, there’s probably a lot less suckling happening. Also, as babies get older and start eating other foods (usually around six months), they rely on breast milk less, so the breastfeeding method of birth control will no longer be effective.
  • Continuous breastfeeding: Again, the key here is the suckling action. If a new mom is not breastfeeding every four hours during the day and every six hours at night because she cannot or because the baby has started sleeping through the night, breastfeeding won’t be a reliable birth control method.
  • No bleeding or spotting: Once a woman starts to bleed or spot, it’s a pretty good sign that she’s fertile again. Keep in mind that a woman can be fertile and ovulate even before she notices spotting and bleeding. Monitoring other physical cues, like body temperature and cervical mucus, might help you stay on top of when you’re ovulating again and your fertility is returning. Check out Fertility awareness: The symptothermal method for information on monitoring fertility.

If you’ve reviewed the list above and think that it might be possible you’re at risk for pregnancy, consider checking in with your health care provider to evaluate whether you’re actually pregnant or not. If you’re not pregnant, there are lots of possible birth control methods out there for you to consider, such as traditional, shorter-term methods like condoms or oral contraceptives, or more long-acting options, like an intrauterine device (IUD). Your health care provider might also be able to help you pinpoint why you’re having irregular spotting.

Originally published Mar 06, 2015

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