So you are ready to start trying to get pregnant, only to realize you don’t actually understand the menstrual cycle. OBGYN Dr. Kenosha Gleaton is here to explain the various phases and when you can actually get pregnant.
While cycles have long been blamed for all things shameful—excess of ice cream, chips, and sleep—they are important indicators of our health and our likelihood of reproductive success.
Overview of the menstrual cycle
The menstrual cycle is a delicate balance of hormonal fluctuations controlling female human reproduction and involves the brain, uterus, tubes, and ovaries. The cycle starts with the beginning of one menstrual period and lasts until the beginning of the next. There are four major events or phases of the menstrual cycle— menstruation, the follicular phase, ovulation, and the luteal phase. Let's take a closer look at each.
Four phases of the menstrual cycle
- Menstruation: Starts on day one of bleeding and lasts up to eight days. Menstruation occurs during the follicular phase.
- Follicular phase: The follicular phase begins with menstruation and lasts until the LH surge. The follicular phase can be 14-21 days and can vary cycle to cycle.The brain releases Follicle Stimulating Hormone (FSH) which stimulates the ovaries, causing five to 20 follicles to develop. Each follicle contains one immature egg. FSH causes only one egg to mature, while the remaining eggs die. Simultaneously, the uterine lining also thickens as a result of the estrogen levels released by the developing follicles. This lining serves as a perfect environment for future implantation of an embryo.
- Ovulation: Ovulation is the release of a mature egg from the surface of the ovary and occurs typically 14 days prior to the next cycle. Ovulation is triggered by a midcycle surge of Luteinizing Hormone or LH and typically occurs within 48 hours of this surge. The ovary releases a mature egg which is funnelled into the fallopian tube and toward the uterus by waves of small, hair-like projections. The lifespan of a released egg is only 24 hours, and if not fertilized during this time, it will die. The LH surge is detectable in the urine with ovulation tests, which can be useful in timing intercourse when trying to conceive. Although pregnancy can occur during the five days prior to and the day after ovulation, it's best if sperm are swimming in the fallopian tubes prior to ovulation occurring.
- Luteal phase: The luteal phase starts with ovulation and ends with the first day of the next menstrual cycle. The term luteal phase reflects the presence of the Corpus Luteum, which is the mature follicle left behind after the egg is released. Its major function is to produce progesterone and estrogen to support the thickened uterine lining in preparation for implantation.
Tracking the days you can get pregnant each cycle
The average adult menstrual cycle is 28-35 days and of those, only six are potential days to conceive. Identifying this often evasive fertile window can be imperative to maximize efforts when trying to conceive. Studies suggest that calendars and phone apps are highly inaccurate in their ability to predict the fertile window and its range. And although more studies are needed, the ability to precisely identify ovulation is not only empowering for some, but can eliminate stressful guess work when trying to get pregnant. To accurately identify ovulation, considering using Natalist Ovulation Tests, which are over 99% accurate and easy to use.