Why are some due dates advanced while others postponed? How long before or after the due date is normal?

We all know that the due date is the estimated time of delivery, which is a rough estimate of the delivery time of pregnant mothers. Generally, many pregnant mothers do not give birth during the pregnancy and delivery period. Some pregnant mothers give birth before the due date, and some pregnant mothers give birth after the due date. So how long before or after the due date is it normal to give birth? Let's take a closer look!

Why are some due dates advanced while others postponed?

First of all, the due date is only a general and preliminary estimate of the production date.

The expected date of delivery is calculated based on the date of the woman's last menstrual period. However, each woman's menstrual cycle and ovulation period are different, so the expected date of delivery is only a preliminary estimate of the delivery date. The specific delivery date must be considered in combination with the data from B-ultrasound testing.

After 37 weeks of pregnancy, the fetus is considered full-term. After the lungs, the last organ of the fetus, mature, the baby will be born soon. Generally speaking, it is normal to give birth two weeks earlier or later than the due date.

Secondly, the nutritional intake of pregnant mothers during pregnancy is different, and the speed of fetal development is also different

Pregnant women with mild morning sickness and balanced and rich nutritional intake during pregnancy generally have better fetal absorption. Compared with pregnant women with severe morning sickness and malnutrition, the fetus is likely to develop faster and mature earlier. In this case, the fetus is likely to be delivered earlier than the expected date, while the latter will be delivered later than the expected date.

Third, the physical differences of pregnant mothers

For pregnant mothers who love exercise, the fetus is more likely to enter the pelvis early. When the fetus enters the pelvis and the cervix softens, the mother will enter labor early.

After full term, pregnant mothers can exercise appropriately, such as climbing stairs, taking a walk, doing prenatal yoga, etc., to speed up the fetus' entry into the pelvis. If the fetus does not enter the pelvis for a long time, a cesarean section may be required according to the doctor's advice.

How long before or after the due date is normal for delivery?

It is normal to give birth two weeks before or after the due date (38-42 weeks). At this time, the baby is full-term, all aspects of the body are fully developed, and will soon be able to adapt to the living environment outside the womb.

Since it is impossible to determine the exact time of a woman's conception, medicine calculates an estimated date of delivery based on the pregnant woman's last menstrual period, known as the due date. However, this is not the exact time of delivery. It only means that the fetus may be born at this time or before or after this time. Only a very small number of fetuses happen to be born on the due date.

The expected date of delivery of a pregnant woman is calculated based on the last menstrual period, so it is not very accurate. As long as the fetus is born between 37-42 weeks of pregnancy and weighs more than 5 kilograms, it is considered a full-term baby.

When is the fetus born and what does it have to do with

1. How fast the fetus develops

There are individual differences in fetal development. If the pregnant woman has adequate diet and the fetus absorbs well, the fetus will develop faster, the actual gestational age will be larger, the time required for fetal development will be shorter, and the fetus may be born early.

On the contrary, if the pregnant woman is malnourished for a long time, the fetus lacks necessary nutrition and the fetus is slow to develop, then the fetus will take a long time to develop and the time of birth will also be affected.

2. Can pregnant women have regular uterine contractions?

Every pregnant woman has a different physical condition. Some pregnant women will experience increasingly intense uterine contractions after their period. Uterine contractions can slowly open the mother's cervix to allow the fetus to be born.

Some women pass their due date and show no signs of labor. Even with oxytocin, uterine contractions cannot be induced. In this case, the only option is a caesarean section.

3. Number of fetuses

Multiple births or twins are more likely to be born prematurely, so the delivery time should be early.

4. Abnormal pregnancy

If a pregnant woman's water breaks first, membranes rupture prematurely, the umbilical cord is severely prolapsed, the fetus is acutely hypoxic, the pregnant woman has gestational hypertension or other kidney diseases, the situation is critical and the doctor can only perform a caesarean section on the mother to try to save the baby's life.