Lesson 4 - Connection Between Hormones and Fertility Signs


  • Discover the roles that hormones play in the female menstrual cycle.
  • Identify the connection between hormonal processes and fertility signs.

Major Points:

  • Certain fertility signs, such as cervical fluid, saliva microscopes, and cervix position, may indicate a rise in estrogen. 
  • The presence of progesterone can usually be determined by charting your basal body temperature (BBT).
  • Some fertility monitors and ovulation prediction kits (OPKs) can measure luteinizing hormone (LH).
  • Before ovulation, it’s common to see an increase in estrogen. 
  • Progesterone typically increases after ovulation and throughout pregnancy.
  • Just before ovulation, luteinizing hormone (LH) increases, causing the ovarian sac to rupture and release the ovum.

Charting your fertility signs is an effective way to determine where you are in your menstrual cycle. Each of these fertility signs is associated with a specific hormonal process in the body. While estrogen and progesterone are the most significant of female hormones, there are numerous others that help the reproductive system work at an optimal level.

Estrogen is one of the most dominant hormones during the follicular or pre-ovulation phase. After ovulation, progesterone takes control during your luteal phase. If conception occurs, progesterone is also the primary hormone during pregnancy. 

Changes in the cervical fluid can clue you in about the presence of estrogen in your system. Fertility monitors and saliva microscopes can also help measure estrogen. The presence of progesterone can be determined by charting your basal body temperature (BBT). Luteinizing hormone (LH) is the last hormone to rise before ovulation. You can determine the presence of LH with some fertility monitors and ovulation prediction kits.

The Role of Estrogen in Fertility

Estrogen refers to a group of steroid hormones designed to regulate the development, growth, and function of the female reproductive system. It’s used to build and strengthen the tissues that make up the uterine lining so that it can sustain a fertilized egg. When speaking about estrogen that is produced by ovarian follicles, it’s called estradiol. Estrogen plays several roles in reproduction:

  • Estrogen signals the release of luteinizing hormone (LH) which is required for ovulation.
  • Estrogen creates extra cervical fluid which helps the sperm travel to the egg located in the fallopian tube.
  • Estrogen helps the cervix soften and open to allow the sperm to reach the fallopian tube more easily.

The Role of Progesterone in Fertility

In the follicular phase before ovulation, estrogen dominates. However, during the luteal phase after ovulation, progesterone becomes the dominant hormone. Before ovulation occurs, the body produces progesterone but only in small amounts. Post-ovulation, progesterone is produced in higher amounts by the corpus luteum. Progesterone plays a number of roles in fertility:

  • Progesterone causes the uterine lining to become soft and spongy which creates the perfect environment in which to implant a fertilized egg.
  • Progesterone causes your BBT to rise post-ovulation and to stay elevated throughout pregnancy.
  • Progesterone is required to sustain a pregnancy.

The Role of Luteinizing Hormone (LH) in Fertility

Luteinizing hormone (LH) typically peaks right before ovulation. This hormone is also responsible for rupturing the ovarian sac that releases an egg. LH can be measured with some fertility monitors as well as ovulation prediction kits. These devices are designed to detect the presence of LH in your urine.

When a high level of LH is detected in your urine, you’re likely to ovulate within 12 to 24 hours. Instead of being released all at once, LH releases gradually over the course of 1 to 2 days. As LH typically begins to rise during sleep in the early morning hours and requires an additional 4 to 6 hours before it can be adequately measured, it’s best not to use first morning urine. Instead, test your urine mid-day to get optimal results.

While ovulation kits cannot always target the day of ovulation, they can help you determine ovulation is near. However, it’s important not to fully rely on the results of an ovulation predictor as you may become fertile before a test measures positive for an LH surge. However, ovulation predictors can be used as part of your fertility charting to help keep track of your cycle.