How Long is a Normal Pregnancy?

How Long is a Normal Pregnancy?

Last update: 03 May, 2018

Pregnancies generally last 9 months, yet not all pregnancies are the same. In this article we’ll explain how to calculate the duration of a normal pregnancy – there are several factors to take into account.

The moment you realize you’re pregnant, begin counting backwards. This is the time to begin to figure out how many weeks your pregnancy will last, and as a result, when you’ll be able to see your child.

Why is it important to know how many weeks pregnancy lasts?

From the doctor’s point of view, it’s necessary to determine the exact time of pregnancy, called the “gestational age.” When the pregnancy comes to an end, the fetus will be ready to be born naturally.

That’s why, upon determining that the due date is approaching, tests will be conducted more often. The mother and baby’s status will be observed, especially their vital signs.

The heart rate and lung development are two of the most important aspects during these tests. Both are linked to the time of birth.

“Knowing with certainty how many weeks a pregnancy lasts will allow  doctors to observe the baby and determine if everything is normal for their gestational age”

How Long is a Normal Pregnancy?

Pregnancy normality

If any anomalies are observed in development, the obstetrician will take the appropriate measures.

Medical science today has many resources to intervene. Above all, any developmental problem for the baby will be diagnosed in advance.

A normal pregnancy is considered “to term” between 37 and 42 weeks. It’s such a wide range because there are many factors and habits that may affect pregnancy.

Generally, mothers that have given birth previously have shorter pregnancies. First-time mothers tend to have slightly longer pregnancies.

Influence of the pregnancy’s duration on birth and the baby 

The length of pregnancy depends on whether it’s a normal, premature, or prolonged birth. If the pregnancy lasts less than 37 weeks, it’s considered “preterm” or premature.

If it passes 42 weeks, it will be a prolonged pregnancy. Both situations are anomalies and should be attended carefully.

  • Premature birth

If a baby is born before their due date, the risks are higher. Babies are born premature when their gestational time is less than 37 weeks.

When the pregnancy begins with the first symptoms of birth before week 37, doctors can recommend steps to postpone birth. Complete rest is one of them.

If birth can’t be avoided, it’s important to have a pediatritian present, in addition to the obstetrician.

A baby that is born prematurely should be monitored during the first few days of life. They should stay in the hospital during this time for monitoring.

  • Birth resulting from a prolonged pregnancy

When the duration of pregnancy exceeds the normal length, the doctor will likely decide to intervene. But why would it be a problem for the baby to stay within the uterus longer than normal?

The placenta only serves the functions of nutrition, immune support, endocrine support, and supporting the baby for 40-42 weeks.

After 40-42 weeks pass, the length of a normal pregnancy, the placenta becomes old and stops to serve these functions.

If the placenta stops working, the baby is exposed to risks, particularly respiratory and nutritional risks. That’s why for pregnancies exceeding 41 weeks, the doctor typically will induce birth.

How Long is a Normal Pregnancy?

How to calculate the length of a normal pregnancy

The length of pregnancy is counted from the first day of the last period. Obstetricians use this date as a guide to begin the count of 40 weeks. The birth date calculated in this way is considered “likely birth date” but is not totally certain.

Ovulation cycles can be irregular in women and this affects the date of fertilization. However, this is a useful tool to estimate the duration of a pregnancy.

The first way to calculate gestation is through the ultrasound conducted in the first trimester. This method is more precise than using the dates of menstruation.

With this ultrasound, the doctor can determine the date that the baby will be born almost with certainty.

Accurately estimating the birth date is important to avoid problems in the child and their mother, as well as unnecessary medical interventions.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.