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Freeflow- The Menstrual Cycle Part 4: The Luteal Phase

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Abbie Tomson

Midwife BSc MSc, Yoga Teacher, All4Birth Lead



The menstrual cycle is a natural process in women and people of reproductive age. A complex interplay of hormones regulates it and involves the shedding of the uterine lining through vaginal bleeding. A cycle typically lasts between 21 to 35 days and can vary in length and intensity from person to person. The menstrual cycle has four phases: the menstrual phase, the follicular phase, the ovulatory phase, and the luteal phase. Different hormonal changes and physical symptoms characterise each phase. Understanding the menstrual cycle can help women track their fertility and identify potential issues or irregularities.

What is ‘the luteal phase’? 1

The luteal phase is a stage in the menstrual cycle that occurs after ovulation and before the start of menstruation. It is characterised by the corpus luteum, formed from the ruptured follicle that releases the egg during ovulation. The main function of the corpus luteum is to produce progesterone, a hormone that helps prepare the uterine lining for a potential pregnancy.

What is typically ‘normal’ in the luteal phase? 1

  1. Ovulation: Ovulation typically occurs around the middle of the menstrual cycle when a mature egg is released from an ovarian follicle.
  2. Corpus Luteum Formation: After ovulation, the empty follicle transforms into the corpus luteum, a temporary endocrine structure in the ovary.
  3. Progesterone Production: The corpus luteum secretes progesterone, which is crucial in preparing the uterine lining (endometrium) for the potential implantation of a fertilised egg.
  4. Endometrial Changes: Progesterone promotes the growth of blood vessels in the endometrium, making it more conducive to implanting a fertilised egg.
  5. If Pregnancy Occurs: If fertilisation and implantation occur, the developing embryo produces human chorionic gonadotropin (hCG), which signals the corpus luteum to continue producing progesterone to sustain the early stages of pregnancy.
  6. If Pregnancy Does Not Occur: If pregnancy does not occur, the corpus luteum degenerates, leading to a drop in progesterone levels. This drop triggers the shedding of the uterine lining, resulting in menstruation and the start of a new menstrual cycle.

The luteal phase length is relatively constant for most women and typically lasts around 14 days. However, it can vary from person to person, with a normal range of 10 to 16 days.

Symptoms that may prompt investigation into your luteal phase 1-5

While variations in the length and symptoms of the luteal phase are normal, certain abnormal symptoms may warrant further investigation. It’s important to note that individual experiences can differ, and what may be abnormal for one person might be within the normal range for another. If you are experiencing any concerns about your menstrual cycle or reproductive health, it is advisable to consult with a healthcare professional for personalised advice. Here are some symptoms that may prompt further investigation:

  1. Short Luteal Phase (Luteal Phase Defect): A luteal phase shorter than ten days may be associated with difficulty maintaining a pregnancy. It could indicate a luteal phase defect, which may be linked to hormonal imbalances or other factors affecting ovulation and corpus luteum function.
  2. Irregular Menstrual Cycles: Highly irregular cycles, with unpredictable variations in the length of the menstrual cycle or luteal phase, may indicate underlying hormonal imbalances or conditions such as polycystic ovary syndrome (PCOS).
  3. Severe Menstrual Cramps (Dysmenorrhea): While some discomfort during menstruation is normal, severe and debilitating menstrual cramps may be a sign of an underlying issue, such as endometriosis, which can affect the luteal phase.
  4. Premenstrual Syndrome (PMS) or Premenstrual Dysphoric Disorder (PMDD): Severe emotional or physical symptoms in the luteal phase, beyond typical PMS, may warrant investigation, especially if they significantly impact daily life.

It’s crucial to consult with a healthcare provider for a comprehensive evaluation and appropriate management if you experience any concerning symptoms related to your menstrual cycle or luteal phase.

Why is an understanding of the luteal phase important when trying to conceive? 1-5

Understanding the luteal phase is crucial when trying to conceive because it plays a significant role in fertility and the early stages of pregnancy. Here are several reasons why the luteal phase is important in the context of conception:

1. Optimal Conditions for Implantation: The luteal phase is characterized by progesterone secretion from the corpus luteum. Progesterone is essential for preparing the uterine lining (endometrium) for the potential implantation of a fertilised egg. A well-developed and adequately nourished endometrium is crucial for the successful attachment of the embryo.

2. Sustaining Early Pregnancy: If fertilisation occurs and a viable embryo implants in the uterus, the corpus luteum produces progesterone. Progesterone helps maintain the uterine environment and supports the early stages of pregnancy until the placenta takes over hormone production.

3. Luteal Phase Defects: In some cases, women may experience a luteal phase that is too short (luteal phase defect), potentially leading to difficulty maintaining a pregnancy. Insufficient progesterone levels or an inadequate response to progesterone can compromise the ability of the uterus to support a developing embryo.

4. Timing Intercourse: Understanding the length of the luteal phase is essential for timing intercourse accurately during the menstrual cycle. The fertile window, which includes the days leading up to ovulation and the early part of the luteal phase, is the most opportune time for conception.

5. Identifying Ovulation: Tracking the luteal phase allows individuals and couples to pinpoint the timing of ovulation better. This information is valuable for those who are actively trying to conceive, as having intercourse in the days leading up to and around ovulation increases the likelihood of fertilization.

6. Monitoring Menstrual Cycle Regularity: Regular and predictable menstrual cycles often indicate healthy ovulatory function. Irregularities in the length or timing of the menstrual cycle, including variations in the luteal phase, may signal underlying hormonal imbalances or conditions that can affect fertility.

7. Seeking Medical Assistance: If there are concerns about fertility or recurrent early pregnancy loss, understanding the luteal phase can provide valuable information for healthcare professionals. Identifying abnormalities or irregularities in the luteal phase can guide further diagnostic evaluations and appropriate interventions.

In summary, understanding the luteal phase is crucial for optimising the chances of conception, ensuring a supportive environment for early pregnancy, and identifying potential issues that may require medical attention. Couples trying to conceive may find tracking the menstrual cycle and paying attention to the luteal phase beneficial in their journey toward parenthood.


Links to other resources


Periods and Fertility in the Menstrual Cycle | NHS

Menstrual Cycle and Getting Pregnant | Tommy’s


It Starts with an Egg | Rebecca Fett

Taking Charge of Your Fertility | Toni Weschler

film-audioFilm Audio

The Menstrual Cycle Animation


Fertility Network

British Fertility Society


  1. Weschler, T. (2016). Taking Charge of Your Fertility: The Definitive Guide to Natural Birth Control, Pregnancy Achievement, and Reproductive Health. Random House
  2. Azziz, R., Woods, K. S., Reyna, R., & Key, T. J. (2004). “The prevalence and features of the polycystic ovary syndrome in an unselected population.” Journal of Clinical Endocrinology & Metabolism, 89(6), 2745-2749. doi:10.1210/jc.2003-032046
  3. Practice Committee of the American Society for Reproductive Medicine. (2014). “Treatment of pelvic pain associated with endometriosis.” Fertility and Sterility, 101(4), 927-35. doi:10.1016/j.fertnstert.2014.01.029
  4. Yonkers, K. A., O’Brien, P. M., & Eriksson, E. (2008). “Premenstrual syndrome.” The Lancet, 371(9619), 1200-1210. doi:10.1016/S0140-6736(08)60527-9
  5. Mayo Clinic. (2021). Menstrual cycle: What’s normal, what’s not.’s%20typical%3F,last%202%20to%207%20days


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