Fetal age and gestational age, what's the difference?

Often when you are pregnant, people ask how old you are in your pregnancy. However, your actual gestational age does not always reflect the true age of your fetus. So, if you are 4 weeks pregnant, it is not certain that the fetus in your womb is also 4 weeks old. This is why, the growth of the fetus in the womb may differ between mothers.

What is the difference between gestational age and fetal age?

Sometimes, when you do an ultrasound at your gynecologist at five or six weeks of pregnancy, the results show that your fetus's age is different from the gestational age you knew from your doctor. Your fetus's age can be smaller or bigger than the gestational age.

This could be due to differences in calculations. Gestational age is calculated from the time of your last menstrual period, even though fetal development has not started until fertilization (the egg is fertilized by sperm). Meanwhile, the age of the fetus is the actual age of the fetus that is growing in your uterus.

Why is the gestational age calculated before conception? Because actually every time a woman experiences menstruation, the woman's body is preparing for pregnancy. This gestational age includes about two weeks before conception, because fertilization generally occurs approximately two weeks or on days 11-21 after the first day of your last menstrual period.

No one knows for sure when conception took place in your uterus, so this is said to be "approx." Gestational age generally lasts for 40 weeks until delivery, when calculated from the time you last menstruated.

Doctors usually use gestational age (for 40 weeks from the time of the last menstrual period to delivery) to estimate when the baby will be born. Meanwhile, when you do an ultrasound, what comes out is the age of your fetus. An ultrasound can estimate how old your baby is by measuring different parts of the baby's body, such as the head, stomach and feet.

What if the fetus is smaller or bigger?

In the second and third trimesters, the difference in age of up to two weeks between gestational age and fetal age (age indicated by ultrasound) is still considered normal. This is because the gestational age is not calculated from the actual day of conception. You don't have to worry about any problems with your baby's development. At the next examination, the doctor may ensure that the difference between gestational age and fetus is not further.

If the fetal age is less than the gestational age

If there is a large difference in gestational age and fetus, this can be worrying. The age of the fetus smaller than gestational age can make the baby look smaller. This can be caused by genetic factors (heredity). Both parents of the fetus have small bodies, so it is passed down to their children.

But often, fetuses that are smaller than gestational age are caused by growth problems in the fetus during pregnancy. This can be caused because the baby lacks the nutrients and oxygen needed for growth and development while in the womb.

If the fetal age is greater than the gestational age

The age of the fetus greater than than gestational age can be seen from the weight of the fetus which is greater than normal. This can also occur due to genetic factors (the baby's parents have a large body). In addition, it can also be linked to the amount of weight the mother gains during pregnancy. A large fetus can also be caused by gestational diabetes that the mother suffers from during pregnancy.

Diabetes during pregnancy can cause the amount of maternal blood sugar that is delivered to the fetus to increase. Then, the fetus's body makes more insulin in response to its body. As a result, the additional flow of sugar from the mother and insulin production in the fetus can cause the fetus to grow bigger and store more fat. So, the fetus looks bigger than it should be at that gestational age.