If you’ve used a метод информирования о рождаемости (FAM, also known as fertility awareness-based methods or natural family planning) to monitor your return of fertility and/or avoid pregnancy during postpartum, you know that there are specific rules and caveats for use during this special season. But why is this?
Admittedly, recent research on послеродовой период return of fertility and menstrual cycles often has small, even very small, study sample sizes. Still, we can understand some general principles about why postpartum cycles are different from regular cycles, and how that impacts your ability to use FAM or ЕПС during this time.
Breastfeeding shifts the hormonal playing field for postpartum mothers
When we say that cycle charting and use of FAM can be tricky during postpartum, we primarily mean for mothers who are breastfeeding, and, in particular, those whose babies directly latch at the breast, hereafter referred to as breastfeeding mothers. (NB: For a fascinating look at why mothers who pump tend to have an earlier return of fertility than mothers whose babies latch at the breast, see здесь.)
In women who are not breastfeeding, return of fertility is expected between six and 13 weeks after baby’s birth, according to a small, old research review (albeit the most recent and “best” evidence available) [1].
Breastfeeding raises prolactin, and prolactin lowers hormones needed to ovulate
For breastfeeding mothers, we know that, generally speaking, the high пролактин levels that accompany lactation suppress the precursor hormones you need to ovulate. Recall that the rise of estrogen in the first part of your cycle, the follicular phase, leads to a surge of luteinizing hormone (LH) that triggers ovulation. The corpus luteum that forms from the leftovers of the follicle after ovulation releases progesterone.
High prolactin from breastfeeding decreases gonadotropin-releasing hormone (GnRH) which leads to less luteinizing hormone (LH) and less follicle stimulating hormone (FSH), which leads to less estrogen and, later on, progesterone. Keep in mind that this relay race-type explanation is a simplified version of a process that actually involves multiple feedback loops between different hormones, all driven by baby’s suckling.
What happens during ‘cycle zero’ before fertility returns
Borrowing Marquette Method terminology, cycle zero refers to the period of postpartum amenorrhea (no period) before fertility returns. Here’s what’s happening inside the body during that time, and why it’s so helpful to work with a trained instructor in an evidence-based FAM or ЕПС method to “catch” the postpartum return of fertility.
Your body goes through a series of warm-ups or practice runs before the real main event, your first ovulation, happens. This is why you can have ‘High’ readings on a Clearblue fertility monitor that не followed by an ovulation. Because of the hormonal changes of breastfeeding, the ovaries may be less sensitive to LH’s effects, requiring much higher than normal LH levels to ovulate for the first time [2]. As an example, 2023 research on the Mira monitor considered an LH surge as being over 15, along with meeting other criteria [2]. My first LH surge in cycle zero was over 170. Of course, the only way to know this scenario is happening from the comfort of your home is to use a quantitative urinary hormone monitor, as with a Mira monitor.
Consider another practice run scenario. Other research suggests that multiple follicles may develop без ovulation occurring [3]. How? Recall that an egg matures inside a follicle, and one follicle becomes dominant in each cycle, eventually undergoing ovulation or release of the mature egg. Practice run-type follicle growth is driven by immature or half-hearted follicle stimulating hormone (FSH) efforts, so estrogen may not rise substantially, even though during normal cycles FSH would drive estrogen way up. Without estrogen rise, you won’t have an LH surge. No LH surge, no ovulation.
You may “get close” to ovulating as suggested by hormone monitor results or other biomarker observations, without signs of овуляция or your period returning, and this might happen over and over. But once your first period arrives or once, if applicable, you have a noticeable rise in progesterone on a quantitative hormone monitor, cycle zero is over.
The first six postpartum cycles have special protocols
Marquette Method and other FAM users will be familiar with the directions to contact an instructor when their cycle returns and then again as they’re approaching their sixth cycle postpartum or if they completely stop Кормление грудью.
That’s because this timeframe, after the first ovulation and period through the end of the sixth postpartum cycle, has a specific protocol separate from the protocol for women in cycle zero (first postpartum ovulation has not yet occurred) or the protocol for after cycle six (when the woman is considered in regular cycles).
How are the first six postpartum cycles different from regular cycles?
Several trends emerged in a small 2025 preprint study of women utilizing the Mira quantitative monitor to assess hormone levels during regular cycles, PCOS, postpartum, and perimenopause [3]. These confirm предыдущие исследования на postpartum menstrual cycle trends в breastfeeding women [4] [5].
Longer cycles
Postpartum women had longer cycles overall, though cycle length tends to shorten with each progressive cycle and gradually normalize. As one example, a woman’s first cycle might be 50 days long, then 42, 40, 35, 30 and 30 in regular cycles going forward.
Longer follicular phase
The reason postpartum cycles tend to be longer than regular cycles is because of delayed ovulation. Remember that the фолликулярная фаза refers to the time between the start of your period and the time you ovulate (sometimes, you’ll read about the pre-ovulation time broken down into the menstrual phase and the follicular phase, but ‘follicular phase’ always means the time before you ovulate). Postpartum women tend to have longer cycles because they have variable and longer follicular phases than regularly cycling women.
In a ‘textbook’ regular cycle of 28 days, a woman might ovulate around day 16 or 17, giving her a 16 day follicular phase. But in a woman with a 50 day first cycle, her follicular phase might be 40 or even 45 days long.
Shorter luteal phase
Above, I wrote that a woman with a 50 day long cycle might have 40 or 45 days of follicular phase. Does that mean her luteal phase, the time after ovulation, could be only five days long? Yes.
In general, women who are still breastfeeding and in cycles one through six have lower estrogen and progesterone levels than women who are regularly cycling… and it shows. While progesterone peaks around seven days after ovulation, in those first six cycles, there can be a relatively weak progesterone rise, leading to a very short luteal phase [2]. Some women will have a four day luteal phase after that first ovulation and then bam! Their period returns [6].
In general, women who are still breastfeeding and in cycles one through six have lower estrogen and progesterone levels than women who are regularly cycling… and it shows. While progesterone peaks around seven days after ovulation, in those first six cycles, there can be a relatively weak progesterone rise, leading to a very short luteal phase. Some women will have a four day luteal phase after that first ovulation and then bam! Their period returns.
Over time, the luteal phase should lengthen
Normally, the luteal phase should lengthen each cycle before becoming very consistent from one cycle to the next.
As an example, with my most recent baby, my luteal phase after my first ovulation was seven days long. In the next cycle, cycle one, my luteal phase was nine days. While technically any luteal phase length greater than nine days is considered normal, ideally in the next cycle or two it will stretch out a bit more to between 12 and 14 days. After cycle six, it should remain rock solid stable from one month to the next at whatever my new normal is. It could be 12 days every time or 14 days every time, but it should not be 10 days one cycle and 13 days the next.
Итоги
Postpartum menstrual cycles may be long and irregular, and they should decrease and normalize over time. Longer follicular phase and shorter luteal phase are expected. Your body will likely go through one or more practice runs before your first postpartum ovulation or the return of your period. As you begin to wean, expect a ramp up in the hormones that drive ovulation. If you are seeking to avoid pregnancy, be sure to work with an instructor trained in your FAM of choice in order to monitor your return of fertility.
Ссылки
[1] Jackson E, Glasier A. Return of ovulation and menses in postpartum nonlactating women: a systematic review. Obstet Gynecol. 2011 Mar;117(3):657-662. doi: 10.1097/AOG.0b013e31820ce18c. PMID: 21343770.
[2] Bouchard TP, Schweinsberg K, Smith A, Schneider M. Using Quantitative Hormone Monitoring to Identify the Postpartum Return of Fertility. Medicina (Kaunas). 2023 Nov 15;59(11):2008. doi: 10.3390/medicina59112008. PMID: 38004057; PMCID: PMC10672941.
[3] Bouchard TP, Fehring RJ, Meyers M, Stujenske T, Boychuk L, Smith A, Schweinsberg K, Scarpa B, Schneider M. Modeling fertile window differences across the reproductive lifespan with quantitative urine hormone monitoring of the menstrual cycle. J Ovarian Res. 2026 Jul 13. doi: 10.1186/s13048-026-02184-w. Epub ahead of print. PMID: 42443950.
[4] Lewis PR, Brown JB, Renfree MB, Short RV. The resumption of ovulation and menstruation in a well-nourished population of women breastfeeding for an extended period of time. Fertil Steril. 1991 Mar;55(3):529-36. PMID: 2001754.
[5] Zinaman M, Stevenson W. Efficacy of the symptothermal method of natural family planning in lactating women after the return of menses. Am J Obstet Gynecol. 1991 Dec;165(6 Pt 2):2037-9. doi: 10.1016/s0002-9378(11)90575-4. PMID: 1755465.
[6] Bouchard T, Blackwell L, Brown S, Fehring R, Parenteau-Carreau S. Dissociation between Cervical Mucus and Urinary Hormones during the Postpartum Return of Fertility in Breastfeeding Women. Linacre Q. 2018 Nov;85(4):399-411. doi: 10.1177/0024363918809698. Epub 2018 Nov 30. PMID: 32431376; PMCID: PMC6322125.
