Understanding the Menstrual Cycle: Phases, Hormones, and Health Insights
The menstrual cycle is a complex interplay of hormones and physiological changes that prepare the body for potential pregnancy. Understanding the different phases of the menstrual cycle can provide valuable insights into women's health, especially for those experiencing issues like PMS, perimenopause symptoms, or trying to optimize fertility.
The cycle begins with the follicular phase, starting on the first day of menstruation, which is counted as Day 1. This phase continues until ovulation, typically around Day 14 in a 28-day cycle. During the follicular phase, the pituitary gland releases Follicle-Stimulating Hormone (FSH), which stimulates the development of follicles in the ovaries. These follicles produce estrogen, particularly estradiol, which supports the growth of the endometrial lining in the uterus. Around Day 7, estradiol levels begin to rise, reaching their peak around Day 14.
Ovulation is a pivotal moment in the menstrual cycle, occurring approximately on Day 14 (varies for everyone!). A strong surge in estradiol sends a positive feedback signal to the brain, triggering the release of Luteinizing Hormone (LH) from the anterior pituitary. The LH peak leads to the release of the mature egg from the dominant follicle about 10-12 hours later. This marks the start of the luteal phase.
The luteal phase lasts from Day 15 to Day 28 on average, but again, every body is different so that’s why tracking your menstrual cycle is so important. After ovulation, the residual sac from the ruptured follicle, known as the corpus luteum, begins to produce significant amounts of progesterone. This hormone helps maintain the integrity and proliferation of the endometrial lining, making it suitable for implantation should fertilization occur. Progesterone is also our chill hormone so I recommend checking your levels if you’re feeling anxious. There is also a slight rise in estradiol during this phase, complementing the effects of progesterone.
If fertilization does not occur, both estradiol and progesterone levels decline rapidly, leading to an increase in prostaglandins. This causes uterine contractions and the shedding of the uterine lining, resulting in menstruation. Menstruation marks the end of one cycle and the beginning of another, starting again at Day 1.
During the follicular phase, FSH stimulates about 15-20 follicles to mature, each producing estrogen to support the growth of the endometrial lining. By around Day 7, one follicle becomes dominant and continues to grow, leading to a significant rise in estrogen. When estrogen reaches a threshold, it triggers the LH surge, causing the dominant follicle to swell and eventually rupture, releasing the ovum. The corpus luteum remains in the ovary, producing progesterone and a slight increase in estradiol to support the endometrial lining.
Understanding these phases can help in identifying hormonal imbalances or health issues related to the menstrual cycle. For women seeking personalized support to address such concerns, holistic nutrition and functional testing can provide valuable insights and tailored guidance for optimal health. Please head to services if you’d like a hair mineral analysis test (HTMA), GI-MAP or DUTCH hormone panel. You may be surprised to learn your mineral levels and your gut health impact your sex hormones.
Q&A
Having a menstrual cycle length of 23 days is considered healthy. An optimal menstrual cycle length ranges from 23 to 35 days, and consistency is key. If your cycle is consistently 23 days, that’s normal for you. However, it is important to monitor for changes, such as your cycle shortening each month or experiencing multiple cycles within a month.
Not having a menstrual cycle can be due to various reasons and may require further evaluation. Possible causes include hormonal imbalances, stress, significant weight loss or gain, and medical conditions such as polycystic ovary syndrome (PCOS) or thyroid issues. I love supporting clients with PCOS and anovulatory cycles.
Low toxin period product options:
Menstrual cups: Made from medical-grade silicone, they are reusable and free from harmful chemicals. Examples include Divacup, Lunette, and Saalt.
Organic Cotton Pads and Tampons: Look for 100% organic cotton products that are free from pesticides, chlorine, and fragrances. Brands include Rael, Natracare, and Organyc.
Period Underwear: Reusable and made from natural materials, they offer a chemical-free alternative. Popular brands include Thinx, Kinx, and Modibodi.
Reusable Cloth Pads: Made from organic cotton or bamboo, they are an eco-friendly option. Brands like GladRags and Lunapads offer these products.
Want to work on your fertility, perimenopause or PMS?
Book in for 1:1 support with or without functional testing. I love offering the HTMA mineral hair testing alongside the GI-MAP for optimal hormonal health. Our gut health impacts our hormones so let’s reduce inflammation by working on your gastrointestinal health.