That's a trick question, actually. It can and does, depending on the circumstances.
Because there are so many rumors and half-truths flying around on the topic, I thought I'd give you a quick look at the facts.
All information is taken from the Ask Dr. Sears website, unless otherwise indicated.
Q. I've heard about something called LAM. What does it stand for?
A. The lactational amenorrhea method (LAM) is a natural birth control technique based on the fact that lactation (breastmilk production) causes amenorrhea (lack of menstruation).
Q. How do I use the LAM method?
A. According to LAM, a mother can rely on breastfeeding for protection from pregnancy if she can answer "no" to the following questions:
1. Have your menstrual cycles returned?
2. Are you supplementing regularly or allowing long periods without breastfeeding, either during the day (more than three hours) or at night (more than six hours)?
3. Is your baby more than six months old?
Q. How effective is LAM?
A. Research shows that LAM's effectiveness in preventing pregnancy is better than 98 percent, a figure that compares well with artificial methods of birth control.
Q. The 6-month mark has passed, but I'm still nursing like crazy. How likely is it that I'll get pregnant?
A. Studies have shown that most mothers who are breastfeeding exclusively remain infertile for more than the six-month period covered by LAM.
Q. My baby is sleeping through the night (six hours or more without nursing). How will this change effect my fertility?
A. The milk-making hormones that suppress ovulation are highest between 1 a.m. and 6 a.m. Nighttime nursing is important to the suppression of fertility.
Q. I want to get pregnant, but I'm still nursing my toddler. How much is breastfeeding effecting my fertility?
A. Sometimes women who are nursing older babies or toddlers want to get pregnant and find this difficult while they are breastfeeding. The baby's nursing may continue to affect a woman's fertility even after her periods have returned. This can be very frustrating. Sometimes getting the toddler to cut back a bit on breastfeeding, especially at night, can make it possible for mother to conceive.
Here's a LAM fact sheet by Family Health International that you can print.
*** As always, please consult your care provider if you have further questions about LAM or about birth control options while breastfeeding.
(Photo by: super-structure)