How to calculate the most accurate expected date? The most accurate calculation method of expected date
Many societies and laws divide pregnancy into three stages. Early pregnancy has a high probability of miscarriage. From the middle stage, the fetus can be tracked and monitored. In the later stage, the fetus begins to have the ability to survive outside the mother. Because of this ability, many laws and customs regard the fetus in this period as an individual.
Calculation of due date (calculation of pregnancy cycle)
Since it is difficult for every pregnant woman to accurately judge the time of conception, it is stipulated in medicine that the expected delivery period is calculated from the first day of the last menstruation, and the whole pregnancy period is 280 days and 10 pregnancy months (28 days per pregnancy month). Pregnant women give birth within 38-42 weeks of pregnancy, all of which are full-term. Because each woman's menstrual cycle is different, it is normal for the estimated due date to differ from the actual due date by 1-2 weeks. The main calculation methods are as follows:
1. Calculated according to the last menstruation:
The month of the last menstrual date plus 9 or minus 3 is the number of months of the expected delivery period; Days plus 7 is the expected date of delivery. For example, Ms. Zhang's last menstruation was March 13, 2008, and her due date is about December 20, 2008. Ms. Li's last menstruation was on May 28, 2008, and her due date is about: March 5, 2009 can also be calculated back from the first day of her last menstruation to the 280 day, which is the due date.
2. Calculated according to fetal movement date:
If you can't remember the last menstrual date, you can calculate it according to the fetal movement date. Fetal movement generally begins 18-20 weeks after pregnancy. The calculation method is: primipara is fetal movement day plus 20 weeks; Pregnant women are fetal movement days plus 22 weeks.
3. Calculated according to the basic body temperature curve:
The last day of the low-temperature segment of the basal body temperature curve was taken as the ovulation day, and 264-268 days or 38 weeks were calculated from the ovulation day.
4. Calculated according to B-ultrasound inspection:
When doctors do B-ultrasound, they can estimate the gestational age by measuring the biparietal diameter of the fetal head, the length of the head and hip and the length of the femur (this method is mostly used for doctors' B-ultrasound diagnosis).
5. Time estimation from the beginning of pregnancy and vomiting:
Reaction to vomiting generally occurs at the end of the 6th week of pregnancy, which is 42 days after the last menstruation, and the expected date of delivery is calculated back to 280 days.
Detection and determination date
The beginning of pregnancy can be determined in several ways. One is to detect hormones produced by the newly formed placenta. Clinical urine and blood tests can detect pregnancy within 6-8 days after conception. Household urine tests usually take 12-15 days to detect effectively. Both methods can only detect pregnancy without knowing the date of conception. Pregnancy can also be determined by the interruption of menstruation. Menstrual interruption precedes any early pregnancy symptoms (e.g. adverse effects). In fact, doctors usually calculate the pregnancy date (i.e. the 'age' of the embryo) based on the first day of the last menstruation reported by women. Unless there is very little sex, there is no way to know the exact date of conception.
Because the date of conception is difficult to determine, embryos and fetuses are only scientifically distinguished, not in actual pregnancy. Conception can also be further divided into fertilization when the egg meets the sperm in the fallopian tube and subsequent implantation.