How to calculate the correct due date?

The article was professionally consulted by BSCK II Pham Thi Tuyet Mai - Department of Obstetrics and Gynecology - Vinmec Hai Phong International General Hospital.

To calculate the exact due date, pregnant women can apply many ways, corresponding to many different calculation times. However, the results of calculating the due date can completely change and there is no fixed milestone to maintain throughout the pregnancy.

In theory, a woman's pregnancy is 9 months and 10 days, but in practice, this number is not completely accurate for all pregnant women. The reason is that pregnancy depends on many different factors, such as the time of fetal maturity, the time of the mother's last menstrual cycle... Therefore, The results of calculating the due date of each person are also not the same. Moreover, the expected date of birth of the mother can completely change and does not remain fixed throughout the pregnancy.
Calculating the most accurate expected date of birth is considered to be the most accurate estimate of the date the fetus is about 40 weeks old, not necessarily the day the baby was born to be called normal. Statistics show that, although the doctor calculates the due date correctly, in reality, only about 1/20 pregnant women give birth on this date, the rest of the baby is born earlier or later within 1 - 2 days. 2 weeks.

However, knowing how to calculate the most standard due date will help pregnant women in the immediate future get a specific milestone and better prepare psychologically to welcome their baby when the pregnancy is full term.
Each fetus will have a certain due date, usually calculated in the 3rd month of pregnancy. Which due date is the most accurate depends on many different factors throughout the pregnancy. If the pregnant woman has been examined at many places, at many different times, but the doctors calculate the due date differently, the pregnant woman should find a reputable antenatal clinic, ask a qualified doctor to carefully check and choose a scheduled date. Which birth is most accurate based on available results (usually ultrasound).

2.1. Calculate the due date by menstrual cycle To calculate the standard due date, pregnant women can count based on the first day of the last menstrual cycle, with the following calculation: Take the first day of the last menstrual period as a landmark, Add 7 days, then add 9 months, to get the expected date of birth. For example, if the first day of your last period is February 21, 2020, your due date is 21+7, February+9, or November 28, 2020.
In this way, gestational age is calculated based on the determination of the menstrual cycle. However, often no one can know the exact day of their own ovulation, as well as the time of conception, only the menstrual date is the most accurate information, so medicine chooses this day to calculate when the baby is born. life. This method of calculating the due date depends on a woman's menstrual cycle. Therefore, this method applies to women who have a regular 28-day menstrual cycle and remember the exact day of their last period. Can not be applied to those who are having irregular menstrual cycles, menstrual disorders, and inaccurately remembering the start of menstruation.

2.2. Calculate the exact due date by ultrasound Pregnant women can calculate the standard due date based on the ultrasound of the first 3 months of pregnancy. Accordingly, the ultrasound doctor measures the size of the fetus, estimates the current gestational age of how many weeks, then calculates the 40-week full day as the due date.
This method does not need to be based on the missed period or the time of conception. Ultrasound results show that: At about 5 weeks of gestation, a fetal pole can be recognized. At 6 weeks of age, the amniotic sac is about 6 - 9mm in diameter. fetal heart beat. The due date is most often determined based on 12 weeks gestation +/_ 7 days
For pregnancy after assisted reproduction, the doctor will calculate the gestational age and due date based on the date of egg retrieval, the date of embryo transfer. or date of insemination.
In addition, today, there are many software, applications and websites that help pregnant women calculate the due date in the most convenient and accurate way. Pregnant women only need to enter all the necessary information (first day of last period, gestational age or date of ultrasound) to know the exact due date.

Usually, the due time will be in the last 3 months of pregnancy. In addition to learning about how to calculate the due date, the first 3 months are the most sensitive time during pregnancy. In order for mother and baby to be healthy, parents need to pay attention to the following issues:
Know the real signs of labor to get to the hospital in time, affecting the health of the fetus. Differentiate between amniotic fluid and vaginal discharge for timely handling to avoid premature birth, fetal distress, and stillbirth. Be especially careful when bleeding in the last 3 months of pregnancy needs urgent emergency care to ensure the life of both mother and baby. Monitor the amount of amniotic fluid regularly and continuously. Monitor fetal weight in the last 3 months to assess baby's development and predict possible risks at birth. The special monitoring group is the same as the striker, and the fetal growth retardation needs to be closely monitored by the doctor and given appropriate indications. Distinguish between physiological contractions, labor contractions and mechanical pregnancy to get to the hospital in time. Maternity services at Vinmec make the pregnancy process easier and safer for pregnant women. During pregnancy, pregnant women will be examined by top doctors in the Obstetrics and Gynecology Department with high professional qualifications and experience, giving the best advice and treatment for the health of both mother and child. little.
Dr. Tuyet Mai has over 30 years of experience in examination and treatment in the field of Obstetrics and Gynecology, especially in lower-line surgery, family planning, specialized laparoscopic surgery, and multi-surgery management. severe and difficult such as:
Hysterectomy, hymenectomy Surgery for uterine fibroids, cervical cancer Cervical cancer vaccination Cervical cancer early detection Cervical electrocautery Examination and treatment endocrine therapy