literature. This presents a problem for the breastfeeding mom who is looking for a contraceptive method that will work. Many times women will ask about the chance of getting pregnant while breastfeeding. This is a very important question and the explanation involves admitting that we have an incomplete understanding of the complex process by which lactation, or breastfeeding, inhibits ovulation and the menstrual cycle.

The concept of lactational amenorrhea (amenorrhea means no menstrual cycle), or LAM is indeed a form of birth control. The mechanism is the result of frequent suckling which results in high levels of the hormone, prolactin. These elevated levels of prolactin alter the production of another hormone, luteinizing hormone, or LH. In order to understand the process of lactational amenorrhea and to grasp the intricacy of our bodies, we must first briefly discuss ovulation.

Ovulation in a ‘nutshell’

1. The ovarian follicle develops by stimulation of hormones from the pituitary, a structure located in the brain. The pituitary secretes follicle stimulating hormone, or FSH. FSH travels in the bloodstream and binds to specific sites called receptors on the ovary.
2. The ovarian follicle requires FSH from the pituitary.
3. The ovarian follicle also requires estradiol.
4. The ovary makes estradiol in response to another pituitary hormone, luteinizing hormone or LH
5. At midcycle, an increase in estradiol triggers the release of preovulatory surges of LH and FSH
6. The follicle secretes predominantly progesterone and the oocyte, or “egg” is released 36 hours later.

In lactation the secretion of pituitary hormones is altered or decreased. Therefore, the growth of the follicle is suppressed because the production of estradiol is suppressed. The suckling of the newborn is responsible for this cascade of events.

Many women wonder when to expect the return of the menstrual cycle if they are breastfeeding. This is a very good question because the return of the menstrual cycle typically signals the return of fertility. For women who are exclusively breastfeeding (no more than 4 hours between day time feedings and no more than 6 hours between night feedings) the earliest possible menstruation is 4 to 6 weeks postpartum. In regards to contraception, the longer the first menses is delayed, the more likely the first cycle will be ovulatory. If the baby is exclusively breastfeeding this causes an increase in prolactin levels and a decrease in LH. Infertility is the result of hormonal suppression during lactation.