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The fertile days

Are some days better than other when you plan to have a baby?

Fertile days

The fertile days are those when a woman is most likely to get pregnant.

In each menstrual cycle there are about 6 days when a woman can conceive: ovulation day and 5 days before that.

What is more difficult, however, is knowing exactly when ovulation occurs

So as to estimate the fertile period, you must keep a record of your menstrual cycle.

Day 1 is the first day of menstruation. Given that the duration of the cycle may vary slightly from one month to the next, it is best to record your menstrual cycle for several consecutive months.

Try to determine on which day ovulation occurs and remember it, by marking it in the calendar of your menstrual cycle. It is an important day. In the following cycle, you will know that the fertile period begins five days before the ovulation day.

The fertile period is the time when you should have unprotected sex at least once every two days if you want to optimise your chances of getting pregnant.

For more certainty in determining when ovulation occurs, we advise you to use Ovulation Tests from the ninth day of your menstrual cycle until the day you get a positive test result.

The fertile period ends the day after ovulation.

Average-length menstrual cycle calendar

There are various ways to identify the days when you are most likely to get pregnant. It is important to remember that the signs of ovulation vary from one woman to another, and many do not experience any symptoms, although ovulation occurs normally. Some of the most obvious signs that can be traced are changes in cervical mucus and increase of the basal body temperature.

Changes in cervical mucus

Cervical mucus is different from vaginal discharge. The same hormones that control the menstrual cycle determine the cervix to secrete a cervical mucus with fertile properties, which protects semen and helps the sperm advance towards the uterus and the Fallopian tubes.

The mucus undergoes changes whenever the woman’s body prepares to release an egg. There are clear differences in how the mucus looks and feels like in different phases of the woman’s monthly menstrual cycle:

  • during menstruation there is no cervical mucus.
  • after menstruation, the vagina is dry and there is no cervical mucus.
  • a few days after the end of menstruation, the cervix begins to secrete the first mucus of the menstrual cycle in rather small amounts. It is sticky, white or slightly yellowish, opaque, it does not stretch and has a slight floury consistency.
  • as the follicles begin to secrete more oestrogen, the mucus becomes more diluted, thinner, moister and creamy. The colour is still opaque white or yellowish. It may or may not stretch a little. All of these elements indicate the beginning of the fertile period.
  • as ovulation approaches, the mucus becomes increasingly more transparent, wetter, elastic, clear and slippery, resembling a raw egg white. This period is very fertile.
  • after ovulation ends, the mucus begins to dry and decrease in quantity. This drying may take place gradually or it may be sudden.

Keep in mind that some actions, such as breastfeeding, or using the douche or other hygiene products, can change the appearance of the mucus.

Observation of signs of ovulation can be challenging at the beginning for some women, but over time many of them arrive to easily recognize these common signs.

Increase of basal body temperature

During the 24 hours of the day, your body temperature varies all the time. During the night (while sleeping), the body temperature gradually decreases until it reaches the lowest point, in the early hours of the morning. As the normal awakening time approaches, the metabolic activity increases, also determining an increase in temperature. At the same time, during the daily activities, the temperature may differ slightly from one moment to another, depending on the level of the activity.

Basal body temperature is the body’s temperature during a relaxed state and it is measured (consistently) in the morning, immediately after waking up, before getting up from bed and eating or drinking anything.

Each woman normally undergoes changes in the basal body temperature during the menstrual cycle. Usually, before ovulation, the basal body temperature is reduced by oestrogen, but immediately after ovulation, when progesterone is secreted, the temperature rises slightly, sometimes by less than one degree, and remains elevated throughout the pregnancy or until menstruation begins, when it will decline again. So as to confirm ovulation with certainty, the basal body temperature should be high for at least three consecutive days.

If you want to measure your basal body temperature, use a more sensitive thermometer, which measures to a hundredth of a degree. Take your temperature at the same time every morning, always before you get out of bed. If you record your temperature every day for several cycles, you will be able to notice a pattern that will help you identify the most fertile days.

Basal body temperature is the fertility sign that confirms whether ovulation has taken place. On the morning when the temperature is recorded as increased, the fertile period of that menstrual cycle may already be over. That is why it is important to check the other main fertility signs that indicate that ovulation is going to occur soon.

Reading or procedural errors make basal body temperature measuring a rather uncertain method of determining the time of ovulation, which is why the use of ovulation tests is preferable. They indicate the ovulation time with much more precision.

There are other signs of ovulation that women may experience, but they do not necessarily occur in every cycle and in all women: spotting, cramps or mild pain on one side of the abdomen, increased breast tenderness, bloating, increased libido, changes in the cervix position or firmness, a heightened sense of smell, taste or vision.

You may not notice all these secondary signs of ovulation. That is fine, it is not a problem. But if you notice them, then these signs can help you identify your fertile days.

The chart below illustrates the evolution of likelihood of getting pregnant in relation to the ovulation day. As you can see, the likelihood begins to increase five days before ovulation, it is the highest on the ovulation day and it drops to zero the following day.

This chart shows the importance of identifying this crucial day in both situations: when you want to get pregnant and when you don’t.

Likelihood of getting pregnant in relation to the ovulation day