The most accurate way to calculate the expected date of delivery is based on the ovulation date.

Many people choose to use the ovulation period to calculate the due date, but this method may not be completely correct. Therefore, when the due date is approaching, people should go to the hospital in time to prepare, relax their minds, and not stay in bed for a long time, otherwise it will make it more and more difficult for their bodies to give birth naturally. They can get out of bed and walk around appropriately to increase their physical strength.

As the follicle develops and matures, it gradually migrates to the surface of the ovary and protrudes outward. As the follicle approaches the surface of the ovary, the surface cells become thinner and eventually rupture. After most of the follicular fluid flows out, the egg is discharged, which is called "ovulation". If the menstrual cycle is very regular, a woman's ovulation date is generally about 14 days before the next menstrual period. Generally, the 5 days before and 4 days after ovulation, together with the ovulation day, a total of 10 days are called the ovulation period.

After the egg is released from the ovary, it can survive in the fallopian tube for 1 to 2 days, waiting for fertilization; the male's sperm can maintain its fertilization ability in the female's reproductive tract for 2 to 3 days, so it is easy to get pregnant through sexual intercourse a few days before and after the egg is released. Because it is easy to get pregnant through sexual intercourse during the ovulation period, the ovulation period is also called the fertile period or the dangerous period. Blood hormone levels, cervical mucus, vaginal exfoliated cell examination, and B-ultrasound can all help determine ovulation.

Normally, ovulation occurs around 14 days before the next menstruation. After ovulation, the body temperature rises by 0.3℃ to 0.5℃ and lasts for about 12 days. If the body temperature does not rise or rises slowly, lasts for a short time or rises less than 0.3℃, it means that ovulation has not occurred or the corpus luteum is not supplying enough energy.

Generally speaking, women will not experience obvious symptoms during the ovulation period, but a few people will experience discomfort during the ovulation period. The main symptoms are decreased appetite, high energy, increased sexual desire, and decreased resistance. During ovulation, women's vaginal mucus will become thinner to allow sperm to pass more easily, thereby increasing the chances of successful conception. At the same time, women's nasal mucus will also decrease, which increases the chances of bacteria invading the human circulatory system. Ovulation bleeding is generally not a large amount and lasts for half a day or several days, and may be accompanied by mild abdominal pain or back pain.