Methods of identifying infertile days or Safe period to avoid pregnancy have been used for over a thousand years. Scientific knowledge gained during the past century has greatly increased the accuracy of these calendar based charts. Menstrual cycles have several days at the beginning that are infertile (pre-ovulatory infertility), a period of fertility, and then several days just before the next menstruation that are infertile (post-ovulatory infertility). The first day of bleeding is considered day one of the menstrual cycle. In this safe period calculator, days 1 to 7 and day 21 to rest of the cycle is calculated as safe for individuals with regular 26-30 days cycles. The ovulation time vary for each individual, and can occur at any time from 12th to 19th day of the cycle. Sperm can live up to 3 to 5 days in a woman’s reproductive tract, so it is possible to become pregnant if unprotected sex occurs few days before ovulation. The life span of the typical egg is relatively short, only around 24 hours. If fertilization does not occur within this time frame, the egg will die. Safe period for intercourse for not getting pregnant may be calculated from online safe period calculator.

Overview

The menstrual cycle, is commonly divided into three phases: the follicular phase (pre-ovulatory phase), ovulation, and the luteal phase (post-ovulatory phase). The length of each phase varies from woman to woman and cycle to cycle, though the average menstrual cycle is 28 days. Menstrual cycles are counted from the first day of menstrual bleeding.
The follicular phase (or proliferative phase) is the phase of the menstrual cycle; before ovulation, during which follicles in the ovary mature. It ends with ovulation. The main hormone controlling this stage is estradiol.
Ovulation is the process in a female’s menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum. The time immediately surrounding ovulation is referred to as the ovulatory phase. A woman gets pregnant around the days when ovulation occurs.
The luteal phase (or secretory phase) is the latter phase of the menstrual cycle. It begins with the formation of the corpus luteum and ends in either pregnancy or degradation of the corpus luteum. The corpus luteum is a temporary endocrine structure, involved in production of estrogen and progestogen, which is needed to maintain the endometrium, the inner membrane of the uterus.
The infertility period depends on the life span of sperm and on the life span of the egg. The average time of ovulation is the 14th day of an average length (28 day) menstrual cycle. Ovulation time vary for each individual, and can occur from 12th to 19th day of the cycle. Sperm can live up to 3 to 5 days in a woman’s reproductive tract, so it is possible to become pregnant if unprotected sex occurs 5 days before ovulation. The life span of the typical egg is relatively short, only around 24 hours. If fertilization does not occur within that time frame, the egg will die.

Calculation Method

In “safe period Calculator Method”, day 1-7 of a regular menstrual period lasting from 26 to 30 days are calculated as “safe”, considering the 3-5 day life span of sperm cells in the female reproductive track. Post ovulatory infertility is calculated based on the fact that; if ovulation occurs on 19th day, fertilization can result until 20th day of the cycle. Since it is a calendar based method, results may vary from person to person.