As soon as the woman ovulates, another hormone takes over and peaks until the body realizes that ovulation has not resulted in a pregnancy, and then it drops significantly so that the endometrium breaks down. The blood coming out of the vagina during this time is menstruation, and this whole process is what we call the menstrual cycle.

The phases of the menstrual cycle may vary for each woman. A cycle considered within the normal range is about 28 to 30 days. However, some women may have cycles lasting from 21 up to 45 days. A woman may be regular or not, and what always varies in these cycles is the duration of the stimulation phase for ovulation. The follicular phase can, in some cases, last about 30 days and in others just a week. Everything depends on the woman's body.

To understand how the menstrual cycle works for a woman with longer periods, let's take an example of a 43-day cycle. The luteal phase should be subtracted from the total. Since it usually lasts about 14 days, let's do the math: 43-14=29 days. This woman probably ovulated on the 29th day of her cycle. In 28-day cycles, ovulation would be around the 14th day. The fertile window is about seven days. We assume she could get pregnant from the 11th to the 17th day of a 28-day cycle. Ovulation will always happen during the fertile window, no matter if it's earlier or later in the cycle.

If the egg is not fertilized, menstruation will start a few days after the fertile period. The symptoms that menstruation is coming are common among many women and can include headaches, cramps, malaise, low blood pressure, and irritability.

There are ways to interrupt this process. Taking birth control pills causes hormonal changes efficiently and alters the menstrual cycle. Women can choose to use oral contraceptives such as pills or hormonal injections.

Other forms of contraception can be used to interrupt a woman's fertile cycle, such as IUDs, implants, and patches. The phases of the menstrual cycle no longer exist because of these ingested hormones, whether they are natural or synthetic.

On the other hand, there are women who want to get pregnant and view their menstrual cycle as their best friend. Sometimes, counting the days until the fertile period can help with getting pregnant. That's why understanding how the menstrual cycle works is an important tool in the search for fertility. If the cycle is too long, beyond the expected 45 days, it will be necessary to consult a doctor to investigate what is happening and also to determine if it is necessary to start proper medication to regularize the menstrual cycle.

Photos: Jen, SCA Svenska Cellulosa Aktiebolaget