Understanding Your Menstrual Cycle

So you all know about the inconvenience (and pain!) of menstruation, and you all know that you're most likely to conceive if you have sex during ovulation, but what else do you know about your menstrual cycle? Do you know why you have your 'time of the month'? Do you know why you're more likely to conceive during ovulation? And do you know about the important changes your body goes through between these two events? No? Well let's take a look at the 4 main phases of the menstrual cycle.

1. Menstrual Phase

This is a phase we all know well, and love it or hate it, it's with us from our teen years through to our 40s, 50s, even 60s depending on when we go through the menopause. There are even reports of two women in the United States conceiving naturally at the age of 73 in the 1800s and early 1900s (although the authenticity of these 'natural' births is, quite rightly, questionable!).

In women of childbearing age, the body assumes that with each cycle we'll become pregnant, and it prepares itself each month for the pregnancy. Luckily, it doesn't quite happen this way. Can you imagine changing all those diapers? We'll look at how the body prepares itself later, but for now we'll look at what happens when the body figures out there's no embryo.

Menstrual cycles last for 28 days on average, although anything from 20 to 40 days is generally considered 'normal'. Towards the end of the cycle, if an egg hasn't implanted into the uterine walls, hormone levels, notably estrogen and progesterone, begin to diminish. These hormones have been keeping the walls of the uterus thick and padded in preparation for pregnancy. When these hormones stop being produced at such a rate, this thick lining begins to fall away.

As with labor, when the body tries to pass something from the uterus, whether it be a baby or the uterine lining, the muscles contract to help push it out. This is why some women experience cramps that are similar to, but much less painful than, labor contractions (never believe anyone who says labor contractions are just like menstrual cramps. They're lying!).

Bleeding usually lasts for around 5 days, but anything from 2 days to 7 days, even 10 days, is considered normal. However, if you notice that your periods change suddenly, either becoming much lighter, heavier, shorter or longer, it's always best to get yourself checked out by your Doctor.

2. Follicular Phase

This is a phase you may not be quite so familiar with, but it's an essential part of the menstruation process as it's when the body begins to prepare itself for a possible pregnancy. During this time, the body releases a hormone called follicle-stimulating hormone (FSH). It's not a particularly creative name, but it's an accurate description of what it does.

FSH stimulates the follicles on the ovaries, encouraging the growth and maturity of the eggs. Usually, only one follicle is affected enough by FSH to fully mature an egg, but in some instances, two, three, four, five and more follicles can be stimulated at once, producing a number of mature eggs which is how we end up with fraternal (non-identical) multiple births.

Cases of natural multiple births, especially larger numbers, are rare. Although twins, triplets etc. can be very cute, they're also a lot of hard work! Recent statistics indicate roughly a 1.6% chance of having a multiple birth. The chance of natural multiple births is thought to increase with age, as hormonal changes in women nearing the menopause can contribute to multiple egg releases each month, or an egg splitting into two. Research has shown multiple birth rates are much higher in the over 35s.

The ovarian follicles secrete estrogen as they're stimulated which encourages the lining of the uterus to build up so it's ready for implantation once the mature egg(s) is released. This lining continues to build until estrogen levels drop and the lining is flushed out.

Many women will notice a slight increase in discharge at this time, and it becomes quite thin and watery, anticipating the upcoming need to help transport sperm towards the egg.

3. Ovulation

We're back to another very familiar phase now. Ovulation is one of the most documented phases of the menstrual cycle as it's the time when you're most likely to become pregnant. In an average 28 day cycle, ovulation will occur roughly around day 14.

The luteinizing hormone comes into play here, breaking down the follicle walls and barriers so that the mature egg is released into the fallopian tube. It's here that the sperm have a chance to fertilize the egg, but they only have a short window of about 1 day before the egg dies.

Fortunately for those wishing to conceive, sperm can live in the body for a few days, so the window of opportunity lasts from about 5 days before ovulation, to around the day of, or day after, ovulation.

There are a number of signs to let us know when we're likely to be ovulating, including a higher basal body temperature (used by monitors to detect ovulation), a thicker vaginal discharge (often compared to egg white) and 'mittelschmerz', literally translated as 'middle pain'; a vague cramp-like feeling in the abdomen. A small amount of bleeding is also normal for some women, although any new bleeding between periods should always be checked out.

Interestingly, some women also experience an increased sex drive during ovulation, thought to be the body's natural way of ensuring the continuation of the species. Research all seems to find a positive link between female-initiated extra curricular activity and ovulation, as well as a significant decrease in sexual activity interest in women using the contraceptive pill, which prevents ovulation occurring.

4. Luteal Phase

The final major phase of menstruation happens when the egg-releasing follicle continues to grow, and secretes progesterone. This progesterone encourages the implantation of a fertilized egg. However, once the follicle dies, the hormone levels drop and if there has been no implantation the uterine lining begins to shed, and the cycle begins all over again.

Alternatively, if a fertilized egg does implant into the uterus, a different hormone, human chorionic gonadotropin, is released which maintains the uterine lining throughout the remainder of the pregnancy, which is why we get a 9 month break from menstruation during this time. It's this hormone that is used to detect pregnancy through home pregnancy tests and blood tests.

Conception

Many women find that understanding the phases of the menstrual cycle, and especially being able to recognize the different phases within their own cycle, greatly increases the chance of conception. While all cycles are different, and some women can become pregnant either at the very beginning or very end of their cycle, the majority of women will only be fertile around the middle; roughly days 10-14. Recognizing when your body is gearing up for ovulation, and knowing when the best time to 'do the deed' is, is one of the best ways to up your chances.