Menstrual Cycle 101

Your menstrual cycle is so much more than an inconvenient monthly occurrence that has you make midnight tampon and Oreo runs. Each phase of it can be used as a window into your health and fertility.

If you’ve been trying to conceive for some time, it’s likely that you know the basics — how to tell when you’re ovulating, what it means to track your basal body temperature, that a missed period isn’t always a sign of pregnancy. But there is a lot more to it and the more you know, the better you can understand your fertility.

Menstrual Cycle Basics

Before we dive into two of the key ways your menstrual cycle can give you valuable information about your fertility, let’s have a quick refresher of what a menstrual cycle is.

First Day of Menstrual Cycle

The first day of your period marks the first day of your menstrual cycle. This is called the menstrual phase and usually last between 5 and 7 days. At the same time the menstrual phase begins, the follicular phase starts. The follicular phase lasts until roughly the 13th day of your cycle.

During this time, your pituitary gland releases a hormone that stimulates the egg cells in your ovaries to grow. One of the egg cells begins to mature (this takes the entire 13 days of this phase to happen). While the egg cell is maturing, your uterus begins to grow a new lining to facilitate the implantation of the egg should it be fertilized.

Your ovulation phase is next and is probably the day you are most concerned with. On this day, usually the 14th day of your cycle but this can vary, your matured egg is released into your fallopian tube to await fertilization.

Final Day of Menstrual Cycle

The final phase of your menstrual cycle is called the luteal phase. This begins the day after you ovulate and lasts until the day before your next period starts. If you released an egg and it was fertilized, it will travel back up your fallopian tube to implant into your uterus. If this does not happen, your uterus will begin to shed it’s lining and you’ll get your period.

This is just a 101 version of a menstrual cycle. It’s important to remember that this is based on averages and every woman is different. You may ovulate on the 14th day of your cycle or you may ovulate at a different time — that’s why it’s so important to track your ovulation when you’re trying to conceive.

The Length of Your Menstrual Cycle

It may be obvious that if you’re not getting a period then you aren’t ovulating. That's something you’ll want to talk to your doctor about. But even if you are getting your period, the length of it can directly impact your ability to conceive. Here’s a rundown on how the length of your cycle can affect your fertility:

  • Normal menstrual cycle — A “normal” menstrual cycle is considered one that lasts between 21 and 35 days, with a menstrual phase of 5 to 7 days. Regular periods are a sign that your hormones are balanced and that you’re ovulating.
  • Short menstrual cycle — If your menstrual cycle lasts 21 days or less, you have a short cycle. It’s possible that a shorter menstrual cycle indicates that you have a decreased number of eggs in your ovaries and that ovulation is not occurring.
  • Long menstrual cycle — Longer cycles, those that last more than 35 days, can occur due to a lack of ovulation and are a sign of hormonal imbalance. This should be addressed with your doctor as hormonal imbalances are often linked to infertility and an increased risk of miscarriage.

To find out how long your menstrual cycle is, track how many days you go between periods. The first day of your period is day 1 of your menstrual cycle. To make this easier, you can use a period tracking app like Clue or Glow. This can also help you track when you’re the most fertile and likely to get pregnant.

Menstrual Discharge and Your Fertility 

Deciphering your discharge throughout your cycle is another great way of learning more about your fertility. During each phase of your menstrual cycle, you’ll have different types of discharge — each of which can indicate how fertile you are.

  • Thick, white discharge — Typically, you’ll have this at the beginning and end of your cycle. This type of discharge will feel pasty and is indicative that you’re at the most infertile times in your cycle. The consistency of this discharge makes it hard for sperm to enter your uterus.
  • Creamy, white discharge — When estrogen levels begin to rise, your discharge will turn from thick to creamy and have more of a tacky feel to it. This type is still hard for sperm to penetrate, especially if the sperm is abnormal. You’ll find this discharge occurs during the week or so before you begin to ovulate.
  • Egg-white discharge — This slippery, stretchy discharge is what you wait for when you’re trying to conceive. The discharge will have the consistency of egg whites (hence the name) and is a sign that you are ovulating and should schedule in some time for baby-making.
  • Lubricating discharge — As you become your most fertile during your menstrual cycle, the egg-white discharge will become more lubricating than stretchy. This will allow it to help the sperm get to your egg that is awaiting fertilization.

Menstrual Cycles are the Starting Point for Fertility

Tracking your discharge may feel strange at first. However, doing so can clue you into many things about your body and fertility. If you notice discharge that is yellow or smells odd, head to your doctor’s office for treatment. This could be a sign of an infection.

Menstrual cycles, as taboo as they still seem to be, are such important indicators of fertility. They are the starting point for the entire process of pregnancy. You can use your menstrual cycle to tune into your body as you try to conceive.

Menstrual Cycle Hormones and Fertility

In reproduction, there are a number of hormones that regulate cycles of egg production, ovulation, and menstruation. If these chemicals drift out of balance, it can be difficult to get pregnant. If this happens, you may ultimately need to talk to a doctor about the following examples of fertility-related hormones.

  • Gonadotropin-releasing Hormone

    (GnRH) is produced in the hypothalamus. It then travels to the pituitary gland and stimulates the secretion of two other hormones, LH and FSH. GnRH is produced in pulses, and the frequency of these pulses determines whether LH or FSH is released. The pulses of GnRH speed up or slow down at different times during the reproductive cycle.

  • Luteinizing Hormone

    (LH) helps regulate a woman’s menstrual cycle. An increase in LH levels triggers ovulation after a follicle has fully matured. Measuring LH levels is a common way to track ovulation. A surge in LH levels typically lasts 24-48 hours and indicates that the mature egg has been released and is ready for fertilization.

  • Follicle-Stimulating Hormone

    (FSH), as the name suggests, is responsible for the development of follicles in the ovaries, the areas where individual egg cells mature before ovulation. Typical levels for a woman of reproductive age are between 4.7 and 21.5 mIU (milli-International Units)/ml.

Effects of Hormones on Fertility - Get the lowdown on menstrual cycle hormones.

Working together, these hormones determine the course of the entire reproductive cycle:

  • Low-frequency pulses of GnRH tell the pituitary gland to produce FSH, which causes the follicle to develop.
  • As the follicle reaches maturity, estrogen levels eventually reach a tipping point. This causes the hypothalamus to increase the frequency of GnRH pulses.
  • This signals the pituitary gland to start producing LH instead, triggering ovulation.
  • Meanwhile, the follicle – now emptied of its egg – develops into the corpus luteum. In turn, this produces progesterone, signaling the uterine lining to prepare for the egg after fertilization.

If levels of any of these hormones are too low or too high, the cycles of menstruation and ovulation can be thrown off, causing fertility problems. Hormone imbalances can be caused by a number of diseases or disorders, including Polycystic Ovary Syndrome, diabetes, drugs including antidepressants, and even stress.

Your doctor may recommend blood tests if they suspect a hormone imbalance is affecting your fertility. Hormone imbalance can be treated with drugs or injections of hormones, or your doctor could try to treat the underlying issue that is causing the imbalance.

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