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Fertility Series #3 : How Hormones Shape Fertility

Updated: Aug 22, 2022

Whenever I think of the hormones related to fertility, I think of the story in the bible about the farmer who scattered his seeds on various parts of his property (Matthew 13: 1-8). The seeds that fell in fertile soil produced "a crop that was thirty, sixty, and even a hundred times as much as had been planted" (Matthew 12:8). Hormones are absolutely essential to reproduction on earth! Both male and female fertility is largely contingent on the cyclical nature of hormones in our body. Each hormone has a main job, but they often influence the jobs of other hormones. They all work together to ensure that your body is ready to create a new life. In part two of this fertility series, we discussed the basics of the menstrual cycle with a focus on the four main phases and I gave a general overview of the reproductive cycle. If you don’t have a basic understanding of the menstrual cycle, I would check this out before continuing in this article. Today, we will be taking a closer look at the hormones involved throughout the month. With each hormone, I will first give an explanation of what science says is happening physiologically and then I will give some clinical or “real-life” signs that your hormone levels are increasing/decreasing in your body.

Follicle Stimulating Hormone (FSH)

FSH is at its highest in the follicular phase of the cycle. At day one of the menstrual cycle, FSH begins to rise and will eventually encourage an egg cell in the ovary to begin to grow in a sac-like-structure called a follicle. At the end of each menstrual period, the biggest of these egg cells begins to grow to maturity in preparation for ovulation. It takes about two weeks for the egg cell to reach maturity. As the egg begins to grow, production of Luteinizing Hormone (LH) and estrogen increase. In relation to the parable I mentioned earlier, FSH is like the farmer choosing the best seeds to plant. In the absence of FSH, ovarian function becomes impaired and may fail entirely. Without proper maturation of egg cells, a healthy pregnancy is unlikely.

Some signs of FSH dysfunction include hot flashes, irregular periods, mood changes, difficulty sleeping and vaginal dryness. These symptoms are often seen in women who are menopausal or perimenopausal as FSH levels tend to drop as ovarian function declines.

Luteinizing Hormone (LH)

Towards the end of the follicular phase, the presence of sustained high levels of FSH triggers a short release of LH that lasts 36-48hrs and leads to ovulation and the remnant of the follicle forms the corpus luteum. The corpus luteum is made up of cells that once surrounded the mature egg and it secretes progesterone and estrogen, which encourage the uterus to continue preparing for a fertilized egg to implant. Without the rise of LH, there is no trigger to release an egg and a pregnancy cannot occur without an egg!

Some clinical signs that LH is high (during a typical cycle) are mild cramps, bloating and one-sided pelvic pain. The presence of other hormones like estrogen and testosterone (in small levels) at this time might also result in glowing skin, increased libido and cervical changes (e.g. positioning and cervical fluid consistency). Most over-the-counter ovulation kits check for the presence of LH in urine to determine when ovulation is likely to occur. Because of how closely linked to the release of a mature egg the presence of LH is, tracking this hormone is incredibly helpful when trying to get pregnant or if you’re trying to prevent pregnancy. I will be discussing how I prevent pregnancy without the use of hormonal birth control next week!

Some signs of LH dysfunction include delayed puberty, hot flashes, infrequent or absent periods and infertility (inability to get pregnant).


Estrogen levels begin to rise in the second half of the follicular phase (after your period). Estrogen is at its highest at ovulation, being produced by the cells surrounding the mature egg in the ovary. It encourages the uterine lining to thicken and soften in preparation for a potential fertilized egg. In relation to the farmer parable I mentioned earlier, I think of estrogen as the fertilizer for the good soil. It encourages the uterus to become the perfect nesting ground for a potential embryo to live and grow.

The combination of estrogen and other hormones present at the same time may result in glowing skin, feeling energized, increased libido, and egg-white consistency cervical fluid. If the egg is fertilized, it will secrete Human Chorionic Gonadotropin (HCG) hormone which tells the body to continue producing estrogen to help the body sustain the pregnancy. If the egg is not fertilized, estrogen levels begin to decline which triggers the deterioration of the uterine lining and the next period begins. Declining estrogen levels toward the end of the luteal phase result in common symptoms of premenstrual syndrome including tender breasts, decreased libido, moodiness/depression, vaginal dryness, hot flashes and trouble concentrating.

Signs of estrogen dysfunction include changes in bones density/skeletal problems, lack of puberty, poor breast development, infertility, mood swings and hot flashes.

Progesterone (P)

Progesterone plays a key role in different phases of the menstrual cycle. P levels decrease right before the start of your period and remain low until right before ovulation. The presence of LH triggers a quick spike in P during ovulation. Levels continue to rise if the egg is fertilized (like estrogen) and levels decline if no pregnancy occurs. P is similar to estrogen in that it acts as a fertilizer for the soil to nurture the growing seed.

Clinical signs that P levels are high include increased fatigue, mood changes, breast tenderness and increases in basal body temperature. Some women have claimed success with tracking ovulation by tracking the P spike, which reportedly can be observed through an increase in basal body temperature mid-cycle. This method, known as “temping”, is most effective when the woman tracks her temperature every day of the cycle because the change in body temperature is fairly subtle.

Signs of progesterone dysfunction include anxiety/agitation, hot flashes, depression, muscular weakness/fatigue, sudden weight gain and infertility.

Human Chorionic Gonadotropin (HCG)

HCG is released once a sperm impregnates an egg and its presence acts as a messenger to the body to continue to sustain the pregnancy. Signs that HCG levels are high include nausea, bloating, mood swings, hot flashes and a missed period. I’ve written several articles about HCG as it relates to pregnancy. You can check one out here for a detailed explanation!


Commonly associated with male reproduction, testosterone plays a key role in the menstrual cycle. It is often at its highest during ovulation and its main role is to increase sex drive. Changes in the level of testosterone often have a direct effect on female libido but can also impact other parts of the system.

Signs of too much testosterone include irregular or absent periods, weight gain, excessive body hair and acne. High levels of testosterone have been associated with polycystic ovarian syndrome (PCOS). PCOS is a condition that affects the healthy functioning of a woman's ovaries and leads to irregular menstruation. The ovaries can also enlarge and grow fluid filled sacs, like cysts, that lead to extreme discomfort and potential infertility.


While each hormone has an important role in the reproductive cycle, they often overlap and are associated with similar clinical symptoms. Understanding the signs can help you better understand what hormones are at work at each stage of the cycle. Ultimately, this will help you become more in-tune with your body and hopefully help you spot subtle changes throughout the month. If you're having any concerns about anything I discussed today, I encourage you to consult a doctor! I am sharing information based on my own research and my personal experiences. This information really comes in handy when trying to prevent pregnancy without the use of common hormonal and barrier birth control methods. Next week, we will be discussing my preferred form of birth control which is the fertility awareness method or the “family planning method”. Be sure to check back in next week for that post! Was this article helpful? Leave a comment below!

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