How long after breast-feeding does lactational amenorrhea (absence of menstruation) normalize with normal hormonal values?

From the Guidelines

Lactational amenorrhea typically resolves within 3-6 months after complete cessation of breastfeeding, though this timeline can vary significantly between individuals. For women who are exclusively breastfeeding, amenorrhea may persist for 6 months or longer, while those who breastfeed less frequently or supplement with formula may see menstruation return earlier. The normalization of hormonal values occurs gradually as prolactin levels decrease when breastfeeding frequency and duration diminish [ 1 ]. Prolactin is the key hormone responsible for both milk production and suppression of reproductive hormones. As breastfeeding decreases, prolactin levels fall, allowing estrogen and progesterone production to increase and the hypothalamic-pituitary-ovarian axis to resume normal function. Some women may experience irregular cycles initially before establishing regular patterns. Factors that influence the duration of lactational amenorrhea include:

• The intensity and frequency of breastfeeding
• Maternal nutritional status
• Individual hormonal sensitivity Women should be aware that ovulation typically precedes the first postpartum menstruation, so fertility can return before the first visible period, making lactational amenorrhea an unreliable contraceptive method beyond the first six months postpartum or when breastfeeding patterns change [ 1 ]. According to the most recent guidelines, if a woman is less than 6 months postpartum, amenorrheic, and fully or nearly fully breastfeeding, no additional contraceptive protection is needed [ 1 ]. However, it is essential to consider individual variations and the potential for early return of fertility.

From the Research

Lactational Amenorrhea Normalization

• The duration of lactational amenorrhea, which is the absence of menstruation during breastfeeding, varies among women, but research suggests that it can last for several months after giving birth 2, 3, 4.
• Studies have shown that the probability of ovulation and pregnancy during lactational amenorrhea increases over time, with cumulative probabilities of ovulation ranging from 30.9% to 67.3% at 6 and 12 months, respectively 3.
• The lactational amenorrhea method (LAM) is a highly effective tool for individual fertility suppression, with a success rate of at least 98% when used correctly 5.
• However, the effectiveness of LAM decreases after 6 months, and other forms of contraception are essential to prevent pregnancy once menstruation has returned 4, 6.

Hormonal Changes

• During lactation, the hormone prolactin remains elevated, suppressing the release of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH), which in turn inhibits ovulation and menstruation 2, 5.
• As the frequency and duration of breastfeeding decrease, prolactin levels decrease, allowing GnRH and LH secretion to resume, and menstruation to return 2.
• The timing of the return of menstruation varies among women, but it is generally associated with the decrease in breastfeeding frequency and the introduction of supplements to the baby's diet 3, 4.

Normalization of Menstrual Cycle

• The menstrual cycle typically normalizes within 1-2 years after childbirth, although this can vary depending on individual factors such as breastfeeding duration and frequency 4, 6.
• Studies have shown that the lactational amenorrhea method can provide effective contraceptive protection for up to 12 months postpartum, but other forms of contraception are necessary once menstruation has returned 4, 5, 6.