What it means to have a full-term pregnancy and 5 ways to boost your chances of carrying to term

• A full-term pregnancy lasts from 39 weeks to 40 weeks and 6 days of pregnancy.
• Outside of this window, babies have a higher risk of breathing issues, low blood sugar, and more.
• You can boost your chance of a full-term pregnancy by eating right, reducing stress, and more.

About 57.5% of all recorded pregnancies are full-term. That's important since a full-term pregnancy gives your baby the time it needs to grow and develop, thus reducing the risk of health problems.

For example, a baby born before full-term has a higher risk of ADHD, autism, cerebral palsy, learning disabilities, and much more.

And a baby born past full-term is more likely to be considered problematically large — which can increase risks of a hemorrhage in the mother, and metabolic problems in the baby.

However, "a full-term pregnancy doesn't 100% eliminate these risks," says Kerry-Anne Perkins, MS, an OB-GYN at Alliance OB/GYN consultants on the medical review board of Women's Health Interactive.

With that in mind, here's what you should know about early-, full-, and late-term pregnancies.

How many weeks is a full-term pregnancy?

A full-term pregnancy lasts between 39 weeks and 40 weeks, 6 days.

Early-term pregnancy (37 weeks — 38 weeks, 6 days)

An estimated 26% of all deliveries happen during this term.

A 2013 study found that early-term babies were at a higher risk of needing respiratory support, intravenous fluids, and intravenous antibiotics, as well as having hypoglycemia and respiratory illnesses.

The study also found that "significantly more" early-term babies required admission to the neonatal intensive care unit (NICU) than full-term babies.

Late-term pregnancy (41 weeks — 41 weeks, 6 days)

About 6.5% of deliveries happen after 41 weeks and are considered late-term or post-term. Late-term pregnancies can raise the risk of certain complications, including postpartum bleeding and severe vaginal tears.

Post-term pregnancy (42 weeks or more)

Post-term birth is linked to increased risk of complications for the mother such as postpartum hemorrhage and dystocia, which is slow and difficult labor due to a large or unusually positioned fetus.

Post-term babies, meanwhile, are at a higher risk of problems such as:

• Injury during birth
• Low blood sugar
• Meconium aspiration
• Low amniotic fluid
• Stillborn or newborn death

Why full-term pregnancy no longer starts at 37 weeks

The American College of Obstetricians and Gynecologists updated the definitions for term pregnancies in 2013. Previously, a pregnancy that lasted between 37 and 42 weeks was considered full-term.

As growing research showed that babies are healthiest when born during weeks 39 and 40, new subcategories with clearer classifications were introduced to reflect those findings for early-term, full-term, late-term, and post-term pregnancies.

Why you might have an early-term pregnancy

One of the leading risk factors of preterm birth is age: Being younger than 17 or older than 35 increases the likelihood of an early-term birth. Beyond age, here are the other leading risk factors:

• Lifestyle risk factors: Your lifestyle is important for reaching full-term. If you have high stress, a lack of social support, exposure to environmental pollutants, or if you smoke, drink alcohol, or use illegal drugs you increase your risk of an early-term pregnancy.
• Multiple gestations: Being pregnant with twins or triplets means you're more likely to give birth early. More than 50% of twin births occur preterm, compared to only 10% of single infant births.
• Reproductive organ abnormalities: Certain abnormalities may occur in your reproductive organs. For example, if your cervix shortens during the second trimester rather than the third, you have a higher chance of preterm delivery.
• Pre-existing health conditions: If you have diabetes or high blood pressure during pregnancy, you're at a higher risk of having your baby early, according to Perkins. You can work with your doctor on managing and treating these conditions and thus, improve the likelihood of a full-term pregnancy.
• Insufficient gestational weight gain: A large 2019 study found that not gaining enough weight during pregnancy was associated with a higher risk of spontaneous preterm birth.

Why you might have a later-term pregnancy

Late- and post-term pregnancies are less common than pre-term pregnancies, but are still serious and you should try to avoid the risk factors, whenever possible.

One of the best ways you can avoid a late-term pregnancy is to maintain a healthy weight as having a high BMI (above 30) during the first trimester of pregnancy is associated with a longer pregnancy.

Other risk factors that you cannot control but should still be aware of include the following:

• You've had a post-term pregnancy in the past.
• You're a first-time mother.
• Your conception date was miscalculated resulting in an inaccurate due date projection.

If you are past due, your doctor may decide to induce labor if your uterus is infected, or you have a medical condition such as diabetes, high blood pressure, or kidney disease. ​​

Other reasons for inducing labor include inadequate amniotic fluid surrounding the baby, or the placenta peeling away from the inner wall of the uterus.

If your doctor isn't concerned about your health or the health of your baby and it's less than 14 days past your due date, they'll likely ​​wait for labor to start naturally.

Note: Labor is usually only induced beyond 41 weeks, according to Rachel Miller, MD, a board-certified OB-GYN. "As long as your OB-GYN has deemed it safe to go beyond 40 weeks, it is absolutely fine to do so," she says.

How to increase your chances of a full-term pregnancy

Preterm and post-term pregnancies can't always be avoided. That said, below are five things experts advise to increase your chances of having a full-term pregnancy.

1. Maintain a healthy diet and stay hydrated

A large 2014 study found that pregnant women who consumed a diet of fresh and raw veggies, fruit, whole-grain cereals, lean poultry and fish, and lots of water were significantly less likely to have a premature delivery than those on a diet high in processed foods.

Prenatal vitamins can help to fill in any nutritional gaps in your diet, thus increasing your likelihood of having a full-term pregnancy and reducing the risk of birth defects.

2. Protect yourself from illness

"During pregnancy, your immune system is lower as your body is focusing its attention on growing a baby," says Miller. "Do your best to stay away from viruses and bacteria."

Miller advises:

• Washing your hands often with soap and warm water
• Avoiding people who are sick
• Letting your doctor if you experience symptoms of a virus or infection, such as a fever
• Avoid raw meat and fish and unpasteurized dairy
• Use condoms if you're worried about STIs
• Ask your doctor about immunizations

3. Keep up with prenatal care

It's important to start prenatal care as soon as you find out you're pregnant, attend all necessary checkup appointments, and communicate any concerns to your doctor throughout your pregnancy, says Miller.

During these visits, your doctor can ensure that you're gaining a healthy amount of weight, and there are no complications that might contribute to an early or late-term delivery.

Prenatal care follow-up visits are typically recommended as follows:

• Every four weeks until 28 weeks of pregnancy
• Every two to three weeks from 28 to 36 weeks of pregnancy
• Weekly from 36 weeks until delivery

It's important to note that the frequency of prenatal visits can depend on your health, age, and other factors. If you have an underlying medical condition, like diabetes, that increases your risk of complications, your doctor may want to see you more frequently closer to your delivery date.

4. Reduce stress in your life

A high level of stress during pregnancy can increase your risk of having a premature baby.

Talk to your doctor about ways you can reduce stress, such as prenatal yoga, meditation, and other relaxation strategies.

You might also consider working with a therapist to find healthy ways to cope with the stressors in your life.

5. Space out your pregnancies

The shorter the lapse of time between pregnancies, the greater your risk for pre-term delivery. That's why it's best to wait 18 to 24 months before trying to conceive again after giving birth.

Insider's takeaway

A full-term pregnancy increases the odds that you have a healthy baby. However, you can also have a healthy baby if you deliver before or after your due date — the risk of complications is just higher in these cases.

Some risk factors for early- and late-term pregnancies are outside of your control, such as being pregnant with multiple babies at once or experiencing abnormalities in your cervix during pregnancy.

However, there are steps you can take to increase your chances of carrying your baby to the full term, such as adhering to a healthy diet, keeping up with all prenatal care appointments, abstaining from drugs, alcohol, and smoking, and protecting yourself from illness.