The return of fertility while breastfeeding is unpredictable, making it difficult to know when the body is preparing to release an egg. Ovulation, the release of a mature egg, must occur before a pregnancy is possible. Because nursing delays this return, many people are uncertain about how to monitor their cycle’s reawakening. Utilizing specific monitoring techniques allows a person to detect the subtle signs that fertility is resuming during lactation. This knowledge is important whether one is hoping to conceive or actively trying to prevent a closely spaced pregnancy.
How Breastfeeding Affects the Menstrual Cycle
The primary reason breastfeeding delays the return of ovulation is the hormone prolactin, which is responsible for stimulating milk production. Suckling triggers a constant release of prolactin from the pituitary gland, keeping levels elevated during frequent nursing. These high prolactin levels actively suppress the normal hormonal signals required for the reproductive cycle to restart. Prolactin inhibits the release of Gonadotropin-Releasing Hormone (GnRH) from the hypothalamus, which disrupts the release of Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH) from the pituitary.
This disorganization of LH and FSH signals prevents the ovarian follicles from fully developing and maturing an egg. This suppression of ovarian activity is known as lactational amenorrhea, which naturally delays the return of menstruation and ovulation. The effectiveness of this suppression is strongly linked to the frequency and intensity of nursing, especially during night hours, which keeps prolactin levels consistently high. When the frequency of feeds decreases, such as when the baby starts sleeping longer stretches or consuming solids, prolactin levels may drop, allowing the ovarian cycle to attempt a return.
Observable Physical Signs of Impending Ovulation
A change in cervical mucus (CM) is one of the most reliable signs that the body is preparing for ovulation. As estrogen levels rise, the cervical mucus typically becomes clear, wet, and slippery, often resembling raw egg whites. This consistency indicates the fertile window because it helps transport and sustain sperm. While breastfeeding, however, a person may notice several patches of fertile-quality CM before the body successfully ovulates, as the cycle attempts to restart and then stalls.
Hormonal fluctuations may cause spotting or light bleeding before the first full menstrual period, signaling changes in the uterine lining. This bleeding can be confusing during the postpartum phase. Some individuals also report an increase in libido, which is hormonally driven and often coincides with the pre-ovulatory rise in estrogen.
A temporary dip in milk supply or increased breast/nipple sensitivity may also be noticed around the time of impending ovulation. The hormonal shifts preceding ovulation can sometimes impact the milk-making process, causing a subtle, short-term reduction in milk production. Tracking these subjective physical changes in combination with other methods provides a complete picture of the body’s attempt to restore fertility. The first cycles while breastfeeding are often anovulatory, meaning visual signs of fertility may not immediately lead to successful ovulation.
Confirmatory Tracking and Testing Methods
Specialized tools and tracking methods can confirm or predict the return of ovulation. Ovulation Predictor Kits (OPKs) measure the concentration of Luteinizing Hormone (LH) in the urine, which surges 24 to 36 hours before an egg is released. While OPKs detect the LH surge, their use while breastfeeding can be complicated because prolactin suppression may keep LH levels low or the returning cycle may be erratic.
Breastfeeding hormones can sometimes cause “false” or multiple small LH peaks, confusing the interpretation of test strips. Starting to track LH levels around six weeks postpartum can help identify when hormonal activity is increasing. For greater certainty that ovulation has occurred, some people use tests that measure the progesterone metabolite PdG in the urine, as this hormone only rises after the egg has been released.
Basal Body Temperature (BBT) charting involves measuring the body’s lowest resting temperature each morning, which typically rises by about 0.5 degrees Fahrenheit following ovulation due to the release of progesterone. The primary challenge with BBT while breastfeeding is the requirement for three to four consecutive hours of sleep before the reading. Frequent night awakenings and night feeds common during lactation can result in erratic and unreliable temperature readings, making the chart difficult to interpret.
Observing the position and texture of the cervix offers an additional sign of fertility. As ovulation approaches, the cervix typically becomes softer, higher, and more open in preparation for receiving sperm. After ovulation, the cervix returns to a lower, firmer, and closed state. Combining cervical changes with cervical mucus and test kits provides the most comprehensive approach to identifying the return of ovulation while nursing.