You’re here because you want to learn the secret code to understanding your ovarian cycle, right? Well, the truth is, there is no secret code. But don’t go just yet! It turns out you don’t need a code to understand the pattern your reproductive cycle goes through.
Here’s a brief guide to your ovarian cycle and how it works. The more you learn about your body’s ovarian cycle, the easier it will be to navigate the complex series of hormone-related emotions and physical sensations you experience each month.
Like the menstrual cycle, the ovarian cycle also helps prepare the body to become pregnant by governing your progesterone and estrogen level and triggering the growth of follicular cells.
How Does the Ovarian Cycle Work?
Most women have a pretty good understanding of how the menstrual cycle works but know very little about the ovarian cycle. If you’re one of these women, don’t worry! Once you read through this guide, the ovarian cycle will hopefully become much more clear to you.
As you probably know already, the menstrual cycle is responsible for preparing and maintaining the uterine lining. The ovarian cycle, on the other hand, is responsible for the release of eggs and preparing the endocrine tissues. Both cycles work together to balance estrogen and progesterone levels and get the body ready for a potential pregnancy.
The ovarian cycle leads to the growth of follicle cells on the ovary surface, and the eventual formation of the corpus luteum (don’t worry, we’ll go over this in more detail later on). This process gets the egg ready for ovulation, fertilization, and implantation in the uterus. Progesterone and estrogen play a very important role in the ovarian cycle and help prepare the body to become pregnant.
If you think about the delicate dance that goes on inside the body every month to create optimal conditions for reproduction, it’s all pretty mind-blowing. While you’re walking around thinking about other things, your reproductive system is hard at work. It’s undergoing complex hormonal changes and releasing eggs without you even noticing. It’s truly amazing!
What Are the Major Events in the Ovarian Cycle?
Like the menstrual cycle, the ovarian cycle typically lasts anywhere between 22-32 days (with the average length being 28 days). It is also composed of three distinct stages, known as the follicular phase, the ovulation phase, and the luteal phase (while the menstrual cycle is divided into the menstrual phase, proliferative phase, and secretory phase). Here’s what happens in the ovarian cycle:
The Follicular Phase
- Primordial follicles develop, which are surrounded by granulosa cells
- Follicle stimulating hormone (otherwise known as FSH) and luteinizing hormone (LH) are secreted from the anterior pituitary gland and help to prepare the mammary glands and reproductive tract for pregnancy
- A dominant follicle emerges during the follicular phase, while the others die-off
- Estradiol production increases, which initiates the formation of a new endometrium layer in the uterus and stimulates the cervix to produce more protective mucus
The Ovulation Phase
- Ovulation (the release of a mature oocyte—or egg—from the mature ovarian follicle into a fallopian tube) occurs
The Luteal Phase
- The pituitary hormones LH and FSH cause the corpus luteum (a mass of progesterone-producing cells in the ovary) to develop from the dominant follicle
- Progesterone and other hormones that support early pregnancy increase
- Either the fertilized oocyte implants in the uterine wall, or luteolysis (the destruction of the corpus luteum), shedding of the endometrium, and menstrual bleeding begins
If the released oocyte (or egg) released during the ovulation phase is not fertilized or implanted during the luteal phase, the corpus luteum will die. In that case, progesterone levels will decrease, and the menstruation phase will begin. The uterine cycle will continue like this until a fertilized egg implants in the lining of the uterus and initiates the stages of pregnancy.
At this point, you may be wondering what a follicle is and why only one dominant, Graafian follicle develops. Ovarian follicles are found inside the ovaries and are small sacs filled with fluid. Primordial follicles are surrounded by a layer of granulosa cells and make up most of the follicles found in the ovary. They release hormones that influence the female reproductive cycles.
What Is the Role of Follicles?
Most women start with approximately 300,000 to 400,000 ovarian follicles when they begin puberty. That sounds like a lot, but by the time you reach age 36, your follicles drop off significantly. That’s why it’s generally harder to get pregnant the older you get.
Each follicle in your body has the potential to release a secondary oocyte for fertilization. The size and health of your follicles and granulosa cells play an important role in your fertility. While the follicular phase of the ovulation cycle stimulates the growth of multiple follicles, only one primary follicle will continue to grow bigger until it releases an egg during the ovulation phase. This is also known as a ruptured follicle (which sounds scary but is perfectly normal!)
It’s important to understand that just because a mature follicle releases an egg does not necessarily mean the released egg is good or mature enough for fertilization. Your eggs need to be in good condition to become fertilized and grow into your own little Mini-Me. Each egg also needs a quality zona pellucida, which protects the egg and embryo during development.
What Is the Order of Hormones in the Ovarian Cycle?
During the three phases of the ovarian cycle, the body undergoes some dizzying changes in hormone levels. Here’s a brief overview of the order of sex steroid hormones during the various phases of the ovarian cycle.
The Follicular Phase
During the follicular phase, several hormone levels rise. These include estrogen, FSH, and LH. The increased estrogen levels come from the Graafian follicle, while the pituitary gland secretes FSH and LH hormones. Gonadotropin releasing hormone (also known as GnRH) is released from the hypothalamus. It’s the hormone that triggers the pituitary gland to produce FSH.
Estrogen causes the endometrium (uterus lining) to thicken and grow in preparation for pregnancy. When estrogen levels peak, they trigger the pituitary gland to release a large amount of LH and a smaller amount of FSH. These two hormones trigger ovulation. Before ovulation begins, the primary follicle stops producing estradiol, one of three estrogen hormones your body produces.
The Ovulation Phase
Estrogen drops rapidly right before the ovulation phase. When the egg is released into the fallopian tubes, the corpus luteum begins producing progesterone. Raising progesterone levels helps stimulate new blood vessels and glands to prepare the body for pregnancy.
The Luteal Phase
In the middle of the luteal phase, progesterone levels peak. If the egg does not implant during this phase, the corpus luteum begins to degrade and break down. Estrogen levels also return to high levels during most of the luteal phase. The increase in both estrogen and progesterone cause the milk ducts to swell, which is why your boobs get so sore just before your period.
If your egg doesn’t implant during the luteal phase, then it disintegrates. Without an implanted egg, your progesterone and estradiol levels drop and trigger the beginning of your period.
If your hormones are imbalanced at any time during your ovarian cycle, you may struggle to become pregnant. Fortunately, you can achieve a healthy hormone balance throughout your cycle by taking Hertime supplements. Made with all-natural ingredients, Hertime balances hormones, and supports women’s health through all reproductive stages.