4hw.com.cn: many expectant mothers have a problem, that is, when they are pregnant. It's very important to know the exact time of pregnancy to aim at the mother and the doctor! Only after the mother to be knows the exact gestational age, can she know when the due date is and when she will go to the hospital for birth examination. For doctors, accurate gestational weeks can help them better understand whether the fetus is normal or not, because the development of the fetus is different in different gestational weeks.
For women with normal menstruation (cycle of 28 days or so) and normal ovulation, most of the clinical medical practice in the world at present starts from the first day of the last menstruation before pregnancy, which is recorded as the start time of pregnancy (i.
For example, the first day of a pregnant woman's last menstruation before pregnancy is January 1, 2017, so the expected delivery date is October 7, 2017 (280 days, 40 weeks). However, you should know that the pre delivery period is not the exact time for a pregnant woman to give birth. Only about 5% of pregnant women will give birth on the day of the pre delivery period. The main role of the pre delivery period is to indicate a time range. Most pregnant women will give birth about one week before and after the pre delivery period.
We need to remind you that some people's menstruation is regular, but the cycle is very short or long. The above method is calculated according to the menstrual cycle is about 28 days. If your menstrual cycle is very short or very long, you need to calculate according to B ultrasound, with irregular menstruation.
For women with irregular menstruation, especially on the day of ovulation, the starting time of pregnancy should be estimated most accurately according to the ultrasound of early pregnancy.
This requires you to go to the regular medical institutions for early pregnancy ultrasound examination after pregnancy, preferably 6-8 weeks after menopause, that is, 40 days to 2 months from the first day of the last menstruation. On the one hand, it can confirm whether it is ectopic pregnancy (commonly known as ectopic pregnancy), on the other hand, the obstetrician and gynecologist can infer your due date according to the data indicated by ultrasound.
If the pre delivery period speculated by ultrasound is consistent with the pre delivery period speculated by the time of menopause (i.e. the whole 40 weeks of menopause), the pregnancy weeks and days of pregnant women can be calculated according to the time of menopause; if the difference between the pre delivery period speculated by ultrasound and the 40 weeks of menopause of pregnant women is large, the ultrasound shall prevail, and the pregnancy weeks and days of every day can be calculated according to the pre delivery period speculated by ultrasound.
If the first day of the last menstrual period before pregnancy is January 1, 2017, but the ultrasound examination of the pregnant woman on February 25, 2017 (8 weeks of menopause) indicates that the embryo has only 6 weeks (that is, the ultrasound gestation week is less than the menopause gestation week by 2 weeks), then the actual pre delivery period of the pregnant woman should be October 21, 2017, and the actual gestation week on February 25, 2017 should be 6 weeks, rather than according to the menopause time Calculated 8 weeks (56 days).
If the ultrasound is not performed in the early pregnancy, and the last menstrual period cannot be remembered, the pre delivery period, gestational weeks and gestational days can also be calculated according to the ultrasound in the middle pregnancy, the time when the pregnancy occurs, the time when the fetal movement occurs, and the height of the uterine fundus.
In fact, pregnant women themselves don't need to know how doctors calculate the expected delivery period and gestational weeks. They just need to remember the actual gestational weeks and gestational days calculated by doctors.