Regular nursing sessions can lessen a woman's fertility. Although it is a nice idea to allow a woman's body time to rest between pregnancies, this can create a real conflict when that woman, like me, is almost 39.
I am part of a relatively new subset of nursing mothers—those whose age necessitates closer-than-ideal spacing between births. Every woman's body is different; some can continue nursing on demand and conceive, while others need to wean completely before they ovulate again. So how do we balance the needs of a current infant against the desire for another child?
Wendy Haldeman, RN, an international board-certified lactation consultant, and one of the founders of the L.A.-based breast-feeding support center The Pump Station, faces this question frequently, as most of her clients are older than 35.
Haldeman encourages mothers to exclusively breast-feed for the first six months, and then, if need be, wean all night feedings. "Often, if moms have a regular 12-hour stretch without suckling, they will ovulate. If not, they have to continue to reduce the number of feedings until they do ovulate." But some moms, she notes, have to wean completely before they are able to ovulate.
How does breast-feeding stave off ovulation?
Although there isn't one clear answer, it seems that high prolactin (the hormone that causes lactation) levels have a lot to do with the continued suspension of ovulation.
Dr. Pamela Berens, MD, an associate professor of obstetrics, gynecology, and reproductive sciences at the University of Texas Health Science Center, at Houston, who researches lactation and breast milk, explained how prolactin levels fluctuate and affect reproductive functioning.
"Baseline prolactin levels typically fall after delivery, and by 2–3 months postpartum, the basal levels are about 40%–50% of initial levels," Dr. Berens says. "Even though the basal level may have dropped, it still roughly doubles with each nursing."
She says that the fall in the basal level is somewhat related to how often you breast-feed, but the pattern and level of prolactin do not accurately predict when your fertility will return.
According to Dr. Berens, prolactin inhibits the normal release of gonadotropin-releasing hormone (GnRH). GnRH is responsible for the release of two hormones—luteinizing hormone (LH) and follicle-stimulating hormone (FSH)—that are crucial to stimulating ovulation. And to make matters worse, when your ovaries are exposed to higher levels of prolactin, the follicles in the ovary do not develop properly.
