A woman’s fertile cycle: find out how your body prepares for pregnancy

The female fertile cycle (also called the sexual cycle or menstrual cycle) is the natural process by which the uterus prepares for a possible pregnancy. During this period, various changes occur in the female body in terms of hormones, temperature and vaginal discharge. All of them are aimed at allowing ovulation, facilitating conception and, if pregnancy occurs, protecting the embryo for its development.

How long is a woman’s fertile cycle?

A woman’s fertile cycle lasts approximately 28 days, although it is considered normal for it to range between 21 and 35 days. These are the days that elapse between the first day of one menstruation and the first day of the next.

A woman’s fertile cycle is divided into three phases:

  • Follicular phase. This phase of a woman’s fertile cycle begins on the first day of menstruation and ends at the time of ovulation. It is the longest phase of the cycle (it lasts an average of 14 days) and determines the time of ovulation and, therefore, the fertile days of each month.

Within the follicular phase, just after menstruation (i.e. between days 6 and 13 of the cycle), the ovary produces more estrogens so that at least one of the eggs inside it matures.

  • Ovulation phase. During this phase of a woman’s fertile cycle, the mature egg is expelled and descends down the fallopian tube waiting to be fertilized. At this time, the female hormone levels are triggered in order to prepare the lining of the uterus for a possible pregnancy.
  • Luteal phase. The third and last phase of a woman’s fertile cycle is from ovulation to the arrival of a new menstruation. If during the days following ovulation there is no fertilization, the body prepares itself for the release of the cells lining the uterus, resulting in a new menstruation and the beginning of a new fertile cycle.
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What are the main changes that occur during a woman’s fertile cycle and what is their purpose?

During the fertile cycle, a woman undergoes several changes in her body. Some of the most common are:

  • Hormonal and body temperature changes. Most of the changes that occur during a woman’s fertile cycle are related to hormonal alterations, mainly to an increased production of estrogen and progesterone. The first causes the endometrium to become denser and helps to create the right environment for sperm survival, while the second causes the basal temperature to increase in women between 0.3ºC and 0.5ºC in the days following ovulation. This increase in temperature can be used to detect which days are fertile and to draw up a calendar of the days with the greatest possibility of pregnancy.
  • Changes in vaginal discharge. Although the appearance and quantity of the discharge vary according to each woman, there are general alterations determined by the phase of the fertile cycle in which she is. Just before and after menstruation, that is, coinciding with the beginning and end of the cycle, on the days when the woman is less fertile, the vaginal discharge is whitish or yellowish, not very abundant and with a sticky texture, since the vagina is not naturally lubricated. However, towards the middle of the cycle and before ovulation, and due to the action of estrogens, changes occur in the vaginal discharge, which becomes increasingly watery, abundant and transparent. The purpose of this change is to help the sperm move to the cervix to fertilize the egg.
  • Changes in libido. Due to the increase in estrogen, as ovulation nears, a woman may experience a greater sexual desire. Generally speaking, during the fertile days, which are the days prior to ovulation and just after ovulation, it is easier for women to become aroused and reach orgasm. The opposite happens in the days before the period, in which the accumulation of liquids can cause uncomfortable discomfort such as a feeling of heaviness and swelling, which will disappear with menstruation.
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Other changes that women experience during the fertile cycle are swelling in the belly and breasts (especially during the days before and during menstruation), and the appearance of acne and mood swings (associated, in both cases, to the hormonal alterations of each phase).

At CREA we are experts in reproductive medicine and we will advise you on everything concerning your pregnancy. In this blog you will also find useful information about assisted reproduction techniques and treatments.