Hormone Series: Introduction and Your Hormones Pre-Pregnancy

Yes you read the title right…we are going there. Hormones are something that often cause confusion for a lot of people and it’s really easy for them to be out of balance and off. During pregnancy and in the postpartum periods your hormones do some pretty incredible things to help you grow and birth this tiny human and we are going to talk about that…but first I want to lay the ground work. I want to talk a little bit about what hormones are (cause although we hear the word all the time…you may not actually know) and I want to talk about the hormonal cycle that women work through each and every month from the onset of puberty to menopause…that’s right we’re talking the menstrual cycle.

I have some interesting personal experiences with regards to my own menstrual cycle, but I’m going to talk about that in a later blog…today I want to talk about (roughly) what the cycle should look like and what hormonal changes take place through a typical menstrual cycle.

First let’s define hormones. Your hormones are a part of the endocrine system and they are produced by endocrine glands (for simplicity sake I’m not going to overwhelm you with all of the endocrine glands in the body). Hormones are your body’s chemical messengers. They travel through your bloodstream and act on different tissues or organs to create a desired (or sometimes undesired) response. Hormones are key players when it comes to growth, development, metabolism, sexual function, reproduction and mood.

So when we consider the female menstrual cycle, it is controlled by hormones. The two main hormones that the ovaries produce and that govern the female menstrual cycle are estrogen and progesterone. These hormones play a role in the development and function of the female reproductive system. Estrogen is responsible for growing and maturing the uterine lining and helps mature the egg prior to ovulation. Progesterone works in the body to balance out the effects of estrogen and you may hear it called the relaxing hormone. It works to build up and prep the uterine lining for pregnancy.

The menstrual cycle is the changes that a woman’s body goes through in preparation for the possibility of pregnancy. The cycle begins on the first day of your period and occurs every 21 to 35 days (28 days is considered average, but if your cycle is different there may not be anything wrong with that). It’s also important to note that as you get older your periods will get more regular and irregular periods in the early years is not uncommon.

Each month one of the ovaries releases an egg. This egg has one of two paths, either it is fertilized, or it is not. Hormone changes drive this cycle and prep the body for fertilization to take place (generally it’s assumed that fertilization will happen). If the egg is fertilized it will implant and the hormonal shifts that accompany pregnancy will begin (we will talk about these next week). If the egg is not fertilized the lining of the uterus sheds and begins to prepare for the next month.

There are three phases of the menstrual cycle and each phase is distinguished by hormonal changes that are taking place

• Follicular Phase – During this phase estrogen and progesterone start at low levels as the thickened lining of the uterus breaks down and sheds (your period). Follicle stimulating hormone will begin to increase during this phase to encourage the development of several follicles (which contain the eggs) but as it falls again only one follicle (egg) will survive. The follicle that survives begins producing estrogen. As estrogen increases the uterus lining begins to prepare for pregnancy and stimulates an increase in production of Luteinizing Hormone. This phase generally lasts 13-14 days in most women but it can vary in length more than any other part of the menstrual cycle.
• Ovulation – Ovulation occurs as Luteinizing Hormone surges. Ovulation is the release of the egg from the ovary and it usually occurs 16-32 hours after the surge begins. Estrogen levels drop and progesterone levels begin to rise during ovulation.
• Luteal Phase – In the final phase of the menstrual cycle luteinizing hormone and follicle stimulating hormone levels begin to decrease and the ruptured follicle (which contained the egg) forms the corpus luteum. The corpus luteum begins to produce progesterone and progesterone levels remain high during this phase. Estrogen also remains high during this phase and together they help thicken the lining of the uterus preparing it for fertilization and implantation of the egg. Generally this phase lasts about 14 days (unless the egg is fertilized). If the egg is not fertilized estrogen and progesterone levels begin to decrease and the lining of the uterus sheds beginning a new menstrual cycle

Throughout your cycle changes will take place with regards to your hormones that will help to prepare the body for pregnancy. If pregnancy does not occur the cycle starts over again. Keep in mind that every woman’s menstrual cycle will look different and if you are not tracking your cycle now I recommend that you start. Tracking can be an insight into your health and you will always know when you should roughly be expecting your period or when a healthcare provider asks you when your last period was you’ll be able to answer accurately. Many healthcare providers are looking at a woman’s menstrual cycle as the 5th vital sign as it can give a lot of insight into overall health. If you’ve never given it much thought maybe it’s time to start.