Understanding Hormones

Ah, how many things you can blame on your hormones! Seriously, hormones have everything to do with your cycles and your ability to conceive a baby. The balance of each hormone has to be just right for a pregnancy to occur. Even a slight variation can lead to fertility problems.

While these slight variations can cause many problems, you should assume your chances of getting pregnant are high until it's proven otherwise. By beginning to know your menstrual cycle you can help determine that your cycles are normal. The focus here is on your normal cycle — whether that is 28 days or 30 days or 32 days.

The process of growing a lining in your uterus, releasing an egg, and conceiving a child depends on many factors, not the least among them hormones. Let's start with the basics.

There are five main hormones to be concerned with when starting to know your cycle. These are the building blocks of your menstrual cycle and future pregnancy — follicle stimulating hormone (FSH), estrogen, luteinizing hormone (LH), progesterone, and gonadotropin releasing hormone (GnRH).

Follicle Stimulating Hormone (FSH)

Follicle stimulating hormone or FSH is a gonadotropin, meaning it affects your gonads: ovaries or testes. In women it stimulates the growth of follicles in the ovary. When it is given in large doses it can cause you to produce more than one follicle. In men, FSH stimulates the production of sperm.


B-estradiol is a form of estrogen that is produced by your follicles. There is very little estrogen in your body at the beginning of your cycle. Your estrogen levels build gradually from day one of your cycle until they peak around days 10–15.

Luteinizing Hormone (LH)

Your production of the luteinizing hormone (LH) begins in the anterior pituitary gland. LH helps stimulate follicle growth in your ovaries. When you experience an LH surge, your body responds one or two days later by releasing the mature egg. It is during the next 12 to 36 hours after the release of the egg that intercourse is advised if you are trying to become pregnant.

While many eggs begin the maturation process, once the LH surge has occurred the process is halted. Many of these eggs will “die” without ever having been released for ovulation. This process is called “atresia.”


As soon as your body has released a mature egg, it begins to secrete progesterone. This hormone helps your body create and maintain the lining of the uterus, the endometrium. The release of progesterone signals your body to stop producing eggs for that cycle. This is why only one egg is generally released per cycle.

Progesterone also causes you to produce more heat. If you are charting your temperature you will see a rise in your basal body temperature as your body shifts into the next phase of your cycle.

Gonadotropin Releasing Hormone (GnRH)

Your hypothalamus, a region in your brain, produces gonadotropin releasing hormone (GnRH). The release of the GnRH from your hypothalamus causes your body to produce more FSH and LH. This hormone is suspected to be more susceptible to stress than others.

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