A woman’s fertility varies throughout the menstrual cycle. The menstrual cycle is the time that passes between the beginning of one menstruation and the beginning of the following. This cycle usually lasts about 28 days, and can be lengthened or shortened depending on individual circumstances, which we will discuss later. Thus, the first day of menstrual bleeding constitutes the first day of the cycle.
The menstrual cycle is divided into two main parts, which last approximately 14 days, if we talk about regular 28-day cycles. The first part is the so-called follicular phase, when the ovaries prepare for ovulation. In this period, the ovum is formed and matured and will be ovulated from the follicle around day 14 of the cycle. This phase may vary according to the ovarian function of each woman. The second part of the cycle is the so-called luteal phase and it is when the uterus prepares to receive the possible embryo that has been generated after ovulation and fertilization. This second phase is of constant duration, always 14 days in all types of cycles.
Thus, after ovulation, the ovum leaves the follicle and reaches the tube, where fertilization usually occurs. For fertilization to be possible, egg and sperm must meet in the tube at the same time. This, which can be very complicated, is favored by the fact that the sperm can remain in the female genital tract and maintain its fertilizing capacity for 48-72 hours. Physiological changes in women during ovulation, such as an increase in body temperature, a change in the consistency of cervical mucus and an increase in vaginal pH, contribute to this.
To summarize, the most fertile period for women is between 3 days before and after ovulation, which in a 28-day cycle would be around days 12 and 16 of the cycle. However, as can be understood, not all cycles are the same and ovulation is not always exact, so the fertile window can be a bit earlier or later.