There are different methods to calculate the fertile days to get pregnant. Taking them into account and establishing an ovulation calendar will let you know which of them is most likely conception.
Women's fertile days
The woman's fertile days coincide with the period of ovulation, which is when the ovum, once reached maturity, detaches itself from the ovary and reaches the uterus through the fallopian tubes.
In the case of women who have regular cycles (28 days), ovulation takes place on day 14 of the menstrual cycle. The oocyte has a survival of 48 hours and the spermatozoa some days more. For this reason, technically, the fertile days to get pregnant are the four previous and two post-ovulation.
Stages of the menstrual cycle and fertile days
It is imperative to know the phases of the menstrual cycle to calculate the fertile days for a woman to become pregnant.
The menstrual cycle begins on the first day of the period and ends the day before the next menstruation. Its average duration is 28 days, although this depends on each woman and may even produce variations from one month to another. Normally the menstrual cycle is not less than 26 days nor more than 30. The menstrual cycle has two phases:
- Preovulatory: begins the first day of menstruation and ends with the ovule detachment. The duration of this phase is variable.
- Postovulatory: goes from the beginning of ovulation to the day before the next menstruation. The duration of this second phase is usually constant and comprises between 12 and 16 days.
In the preovulatory phase we distinguish between menstruation and follicular phase. In the latter, estrogens make the inner lining of the uterus, the endometrium, thicker and more comfortable to accommodate a possible fertilized egg.
In the postovulatory phase we distinguish between ovulation, which lasts between 3 and 4 days, and the luteal phase. In the luteal phase the follicles become a substance called corpus luteum, responsible for generating progesterone. This process is interrupted when there is no fertilization and the wall of the uterus detaches resulting in a new bleeding (rule) with which a new menstrual cycle begins.
How to calculate the fertile days?
According to the specialists in Assisted Reproduction , to calculate the fertile days it is fundamental that the menstrual cycle is regular. If it is, it will be possible to establish an ovulation calendar and fertile days quite precise. If, on the other hand, the menstrual cycle is irregular, locating the beginning and end of ovulation to know when the fertile days are more difficult and less precise and therefore, it will be necessary to consult a fertility specialist.
To calculate the fertile days for pregnancy according to the menstrual cycle the following variables are used:
- Last menstruation
- Average duration of the menstrual cycle
- Mean duration of the luteal phase
An easy way to know the fertile days is to subtract between 12 and 16 days, corresponding to the duration of the postovulatory phase, to the first day of the following rule. If the menstrual cycle is regular, the fertile days of the next month can be calculated with this method.
For women with less regular menstrual cycles ranging from 26 to 32 days, the best option is to subtract 18 days from the days of the shortest menstrual cycle and 11 to the days of the longest menstrual cycle. Thus, the first day of probable fertility would be the 8th (26-18 = 8) and the last the 21st (32-11 = 21). It is a total period of 13 days in which not all will be, but among them are the five or six most fertile.
Method of basal temperature
Another option for calculating fertile days is by controlling the basal temperature. It is about taking the temperature every day, with the same thermometer and at the same place and time, and record the results in a table.
The progesterone present during the second phase of the menstrual cycle causes the temperature to rise by about 0.5 ° C. Once the temperature peaks are located, it is relatively easy to know the most fertile days.
This method requires constancy and patience, and you have to take into account, for example, a possible increase in the temperature of the woman in case she is sick or has been able to increase her body temperature for some other reason. In any case, there are special thermometers that can be purchased in pharmacies and have a division in tenths of a degree easier to read to control the basal temperature.
Luteinizing hormone (LH) level control
Another simple and reliable method to calculate fertile days is to control the amount of luteinizing hormone (LH). LH is the cause of ovulation and secretion of progesterone. It can be located through a urine test between 24 and 36 hours prior to ovulation. This test is sold in pharmacies and is easy to use.
Fertile days can also be calculated by paying attention to the signals the body sends during ovulation. Ovary discomfort, similar to menstrual discomfort but less severe, or the breasts are more swollen and tender.
Other physical indications are the color and texture of vaginal discharge. It presents appreciable changes throughout the menstrual cycle and is more abundant, transparent and liquid during the most fertile days, due to the increase of estrogen levels.