Menstruation to Ovulation

Week by Week Timeline >> Menstruation to Ovulation

Week-by-Week Pregnancy Calendar: Your Menstrual Cycle

Trying to conceive a baby? Fantastic! The purpose of this five-part article is to provide an in-depth and informative look at achieving pregnancy - on a week-by-week (and even day-by-day) basis - starting from the very first day of your menstrual cycle all the way through ovulation, conception, pregnancy testing, your missed period, your first trimester pregnancy symptoms, and the growth of your baby during the early weeks of pregnancy!

Learning about fertility and conception is the first step in increasing your odds of getting pregnant sooner and healthier... We have a lot of ground to cover, so take your prenatal vitamin and lets get started....

Week 1: Your Menstrual Cycle & Menstruation
Let's start from the very beginning of your cycle - menstruation. Cycle Day 1 is the first day of your period or 'menstruation' - the first day you see red blood. The duration of your period will typically last anywhere from four to eight days, and women may experience different physiological symptoms prior to and during their periods, from cramping and fatigue to irritable moods and even headaches. Some women even experience intense migraines.

Menstruation is defined as the cyclical shedding of the endometrium, the lining of the uterus or womb. As we shall see, the first part of your menstrual cycle following your period is "dedicated" to building up the endometrial tissues in preparation for pregnancy. Networks of blood vessels develop in the endometrium and circulation increases to your reproductive organs. If pregnancy is not achieved, the endometrium is shed at the end of your monthly cycle, resulting in menstruation (or your period).

Why does menstruation take place? Good question! The first part of your cycle is all about building the uterine lining for pregnancy, and to this end specific hormones (estrogen and progesterone) trigger your body to facilitate endometrial blood flow and tissue development. If pregnancy is not achieved during a discrete cycle, the levels of these key hormones will sharply decrease and, subsequently, so decreases the blood flow to your endometrium. Once circulation is cut off to the endometrium, the lining of the uterus deteriorates and sheds, resulting in menstruation. Your period is the indubitable signal confirming you have not achieved pregnancy during the preceding cycle.

It's important to note that even during menstruation, other hormones are already active and have started the fertility ball rolling for this next menstrual cycle. The fact is, the menstrual cycle is dynamic: there is a never a static moment, never a definitive start or an finished ending, and even the sharp decline in estrogen and progesterone that causes menstruation also functions as a hormonal trigger to begin production of other fertility hormones like GnRH (gonadotropin-releasing hormone) and FSH (follicle-stimulating hormone). Even during menstruation, GnRH is secreted by the hypothalamus in the brain, which in turn stimulates the pituitary gland to produce follicle-stimulating hormone. A "follicle" is an assemblage of cells in the ovary that contains an ovum (or egg); therefore, FSH is the hormone that tells your ovaries to start the maturation process of between three and thirty ovarian follicles.

Week 2: From Follicular to Ovulatory Phase
So even during menstruation, your body is already active in preparing you for the next fertile opportunity to get pregnant. During this early "follicular phase", the production of GnRH and FSH begins the maturation process of the ovarian follicles. During the first week of your menstrual cycle, FSH levels are high. However, during week two of your cycle, FSH levels rapidly decline and typically a single dominant ovarian follicle will continue to develop while the other follicles will simply drop out of the race. As the dominant ovarian follicle grows, it begins to produce another key reproductive hormone, estrogen.

Estrogen plays several roles during the ovulatory phase. With the flow of estrogen, the endometrium (or uterine lining) again begins to build. The development of blood vessels, endometrial secretions, and tissue build-up in the uterus is key to successfully achieving pregnancy, as a fertilized egg will eventually "implant" in the endometrium. Following your period, the endometrium is just a few millimeters thick; however, during the ovulatory phase, the endometrium builds itself to around ten millimeters thick (see image below).

Estrogen also facilitates the secretion of cervical mucus from cells in the cervix. Cervical mucus, as we shall see below, if central to fertility and assists in helping protect, nourish and transport sperm to the awaiting egg. Finally, estrogen also triggers the production of Luteinizing hormone, or LH, from the pituitary gland in the brain. During the latter part of the ovulatory phase, the amount of LH in your system increases rapidly. Like estrogen, LH performs a number of "tasks", facilitating fluid to develop in the ovarian follicle. More importantly, LH causes the surface of the ovarian follicle to break down, which will ultimately lead to ovulation itself. That's why our urine ovulation tests are designed to detect this specific hormone in order to alert you to the fact that ovulation is imminent and that you are now fertile!

So far, we have covered the first two phases of your menstrual cycle - the follicular phase and the ovulatory phase leading up to ovulation. For many women, these two phases last about two weeks, starting from cycle day one (the first day of your period). Of course, 14 days to ovulation (the first half of a 28-day cycle) is an idealized construct and many women may have shorter or longer cycles. 28-days is an average, not a "norm", so your menstrual cycle may be a bit longer or shorter. Here, fertility charting (or developing an ovulation calendar) is a great way to learn more about your unique cycle, and to help you know when you are most fertile. By maintaining a fertility chart, you can determine when you ovulate during each discrete cycle so you can time lovemaking accordingly.

From here, let's look at the next two weeks of your menstrual cycle, starting with ovulation.

> Week 3: From Ovulation to Conception

See Also:
> TTC Week 4: Implantation and the Luteal Phase
> Pregnancy Week 1: Early Pregnancy Symptoms & Fetal Development
> Pregnancy Week 2: What to Expect During Your First Trimester
> Pregnancy Calendar Home