Pregnancy is not possible just by having sex, but only when a woman expels a mature egg cell and unites it with a man’s sperm. Generally, a woman only expels one egg cell in a month and ovulation occurs 14 days before her next period. The ovulation period can be delayed or advanced by many factors such as women’s emotions and stress. Therefore, ovulation is possible five days before and four days after the ovulation period, which is called the ovulation period or the fertile period. 1. The egg can survive 1-2 days after ovulation The egg can survive 1-2 days in the fallopian tube after being discharged from the ovary to wait for fertilization; the man’s sperm can maintain its fertilization ability in the woman’s reproductive tract for 2-3 days, so sex is easy to conceive in the days before and after the egg is discharged. The 5 days before and 4 days after the day of ovulation, together with the day of ovulation, a total of 10 days are called the ovulation period. Because it is easy to conceive during ovulation, the ovulation period is also called the fertile period or the risk period. 2. 1 day for fertilization The ovulated egg takes some time to reach the abdomen of the fallopian tube, where it waits for sperm, usually about 10 hours, i.e. fertilization occurs within 12 hours after ovulation; the moment when sperm and egg meet and fertilize is called fertilization, and the process of fertilization itself takes about 12 hours for the sperm to combine with the egg, i.e. the whole process of fertilization needs to be completed after 24 hours of ovulation. 3. 10-12 days to conception It takes 10-12 days for the fertilized egg to swim from the abdomen of the fallopian tube to the uterus and implant itself in the endometrium (bed), which is then called conception. If pregnancy is not successful, the corpus luteum retreats, progesterone levels drop, and menstruation returns.