Calculating gestation weeks based on a woman's ovulation period is not the most accurate, as ovulation is a specific date and fertilization is a general time frame that is more or less wrong. In medicine, pregnancy is basically based on the time of the last menstrual period, rather than starting from the time of ovulation, because everyone's menstrual cycle is different, so the specific time of ovulation will also have some differences.
For women with regular menstruation and normal ovulation, it is the last menstrual period before pregnancy.
From the first day, the time of pregnancy is recorded, followed by an additional day of each day, 7 days for a week, and 40 weeks for the expected date of delivery.
If the woman usually has irregular menstruation and the ovulation period is usually irregular, it is best to go to a regular medical institution for early pregnancy ultrasound, and the doctor can infer when the expected date of delivery will be performed through the ultrasound prompt data.
Many people think that calculating the number of days of pregnancy starts directly from the last sexual life and then until now it is possible to calculate how many days of pregnancy, in fact, this is not true. Because sex doesn't mean you can get pregnant, some sex may be pregnant and some aren't, so the sex time is not very strict, but it needs to start from the last menstrual time so that the pregnancy time can be more accurate.
Under normal circumstances, pregnancy usually comes from the last menstrual period.
Day 1 or calculated to estimate the current number of days and the expected date of delivery. If you don't have confidence in yourself, you can also go to the hospital for an ultrasound to extrapolate the time of the expected date of delivery. Doctors can also tell what precautions are available during the expected date. Couples only need to stay healthy with the help of a doctor.