One of the most exciting parts of your pregnancy journey is getting your due date. You mark the day on your calendar and share the very anticipated date with friends and family. You’ve probably heard most people say the average pregnancy lasts 9 months but is this really the average time? Turns out – it’s not! Though there is a general gestational period, there are many factors that can affect the length of your pregnancy. 

If you are 9 months pregnant, it may feel like it’s already been forever! Learn more about the real average pregnancy time and what is considered early or late term.

What is the Average Pregnancy Length?  

To be more exact, the average pregnancy lasts about 280 days or 40 weeks. This is where the misconception that a full-term pregnancy is nine months comes from. Not every month has the exact same number of days, meaning some may be nine months and some may be ten. Generally speaking, a pregnancy is made up of three trimesters of 13 or 14 weeks. Why isn’t it exact? Try dividing 40 (weeks) by three and you’ll see why. Even though this is the average length of a full-term pregnancy there are many factors that can still affect your gestational term.

What Factors Can Affect Pregnancy Length?

Did you know that only 1 in 20 babies are born on their actual due date? That’s right! 95% of babies are born before or after their said due date. This is because your due date is just an estimated birth date but there are many factors that can affect whether your baby is born prematurely or after the due date. The mother’s age, birth weight, progesterone levels, and the length of previous pregnancies may affect gestation times. The number of babies you are caring, whether it is one or triplets, can also affect the length of time of your pregnancy from conception.

Happy Couple Looking at Pregnancy Progress on Ultrasound

Are All Pregnancies the Same Length? 

Pregnancy length varies greatly from woman to woman and everyone’s experience is different. Most normal pregnancies last between 38 to 42 weeks, keeping most parents guessing on the birth date up till the delivery day. A baby may safely arrive at any point within this time frame. Health care professionals use a number of common terms categorized by The American College of Obstetricians and Gynecologists to describe baby arrivals. These include: 


A preterm or premature baby is delivered before the 37 weeks mark of pregnancy. 
Moderately preterm infants are born between 29 and 33 weeks of conception.
Extremely preterm infants are born between 23 and 28 weeks.

According to the Centers for Disease Control and Prevention, in 2020 roughly 1 in 10 babies were born preterm in the United States.

Premature babies often need the support of a neonatal or the newborn intensive care unit (NICU) due to increased health risks. This could include help with breathing, regulating temperature, managing sugar levels, or feeding.

Early Term

Early term babies are born between the 37 week through 38 weeks and 6 days. Early term pregnancies may not need the help of the NICU but they may still need extra care. 

Full Term 

A full term pregnancy is considered one lasting 39 through 40 weeks and 6 days starting on the day of conception. The length of a full term pregnancy can vary however depending on the amount of children you are carrying. A full term pregnancy from a woman carrying twins is considered at least 38 weeks. If you are planning to deliver your baby by cesarean section, a full term would be considered right at the 39th week. This is because these procedures are usually done before the woman naturally goes into labor. 

According to the CDC, in 2020  roughly ​​57% of babies born in the United states were full-term births. 

Late Term

Late-term pregnancies are considered those born from 41 weeks and up to 41 weeks and 6 days. This is because at this point the risks of continuing the pregnancy increase the longer it takes. Late term pregnancies are often put into induced labor to prevent any health risks. 


A post term baby is born anytime after 42 weeks of conception and beyond. It is often the case that babies are born post term due to the original due date being miscalculated.

Pregnant Woman Sitting on Bed Holding Belly

What is the Average Pregnancy Length for First Time Mothers?

You probably understand that there are many factors affecting pregnancy length at this point. And this is the case for first time mothers or if this is your second time around (or third, or fourth…) However, research shows that the length of previous pregnancy can affect the length of future ones. First-time mothers also have a higher chance of having a post-term birth.

Now you understand why you probably shouldn’t focus too much on your due date. Remember that this date is just a rough estimate and not set in stone. No two mothers are the same and no two pregnancies are either. Some babies may naturally arrive early, late, or on time.

Your due date basically sets the stage for the unpredictable nature of parenthood. It’s better to let go of the things you don’t have control over and let your medical staff take care of the rest. If you’re looking to take the first step in your family planning journey, make an appointment with a fertility specialist at Red Rock Fertility Center to discuss solutions to help you grow your family!

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