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What Are The Causes Of Premature Birth?

Top Causes Of Premature Birth

Preterm birth can be caused by conditions like preeclampsia and HELLP syndrome. Early uterine contractions or having twins (or more) may also induce early delivery. If you have a family history of preemies or have had one before, your risk increases. It’s also likely if you’re a teenager, over 40, have chronic stress, drink alcohol, or smoke cigarettes. Wait at least 18 months to prevent premature birth.

Pregnancy is an amazing experience. And when your baby’s health is your biggest concern, it’s crucial to learn about preterm births. After all, it’s responsible for 60 percent of deaths and complications. About 12 to 13 percent of all births in the United States are premature.1

Fortunately, most “preemies” grow up to be perfectly healthy and fine! But it doesn’t hurt to learn about premature labor and delivery, starting with these top causes.

Top 8 Causes Of Premature Birth

Pregnancy complications can be reasons for premature birth


About 3 to 7 of all pregnant mothers will get preeclampsia. It develops after the 20th week of pregnancy and is marked by high blood pressure and protein in the urine. If it’s left untreated, this disease may cause preterm birth or death.2

HELLP Syndrome

As a variant of preeclampsia, HELLP consists of three conditions that can cause preterm birth: H (hemolysis, or breakdown of red blood cells), EL (elevated liver enzymes, or liver function), and LP (low platelets, which help blood clots). This syndrome is life-threatening, but it’s also rare. Only 0.2 to 0.6 of all pregnancies will experience HELLP.3

Uterine And Cervical Abnormalities

Sometimes, uterine contractions can start early, sparking premature birth.4 It can also happen if the uterus is abnormally shaped or the cervix can’t stay closed by itself.5

Genital Infections

Infections in the lower genital tract are associated with preterm labor and delivery. This is especially true with bacterial vaginosis (BV), which develops in 10 to 30 percent of pregnant women.6 It’s responsible for 6 percent of preemies but can also cause postpartum endometriosis.7

2. Pregnancy History

History of Miscarriage or abortion causes premature babies

Previous Premature Birth

Preterm birth is more likely if you’ve had one before. The risk can also skyrocket if you’ve had a miscarriage, especially if it was in the last trimester. Small babies and perinatal death may also happen after a previous premature birth.

Past Abortion

A past abortion is another cause. This risk increases if you get pregnant within six months of the abortion, so it’s best to wait a while. The baby may also experience growth restriction during its early years.8


If you’ve had a rocky pregnancy history, not all hope is lost. You can lower your risk of future preterm births. Work with your doctor to plan before you even start trying to conceive. Focus on helping your health thrive by managing weight, regularly exercising, managing stress, and eating well. If have conditions like blood pressure or diabetes, work on controlling them. These habits will set you up for a healthy, normal pregnancy.9

3. Having Multiple Babies At A Time

Having twins or triplets may Cause Premature Birth

Expecting twins, triplets, or more is exciting! But it’s also one of the main causes of prematurity. In fact, pregnancies with multiple babies are almost always preterm. The American Pregnancy Association shares that about 60 percent of twins are born prematurely. As for triplets? About 90 percent are born preterm.

Compared to the 39-week length of single babies, twins usually last for 36 weeks. Triplets typically last for 32 and quadruplets last for 30. The pregnancy length will decrease with each additional baby.10

If you’re pregnant with multiple babies, you’ll need more frequent prenatal visits. Your doctor will keep a close watch to make sure there aren’t any signs of premature birth. Extra tests might be done to check the health of each baby.11

4. Family History

family history can definitely influence Premature Birth

Having a family history of preemies can definitely influence your own pregnancy. This includes siblings who were born prematurely. The risk is even higher if you were a preemie yourself, along with other factors on this list.

Genes can also play a part in terms of race. Black women have a 17 percent risk of spontaneous preterm birth, while whites only have 10 percent. If you have any of these inherited predispositions for premature babies, keep up with prenatal appointments.12

5. Mother’s Age

Mothers ages have the highest rate of preterm deliveries

When it comes to pregnancy, age matters. Teen mothers ages 14 to 17 have the highest rate of preterm deliveries, especially if it’s the second child. The risk is a bit lower for teens ages 18 to 19 but is still noteworthy.13

Being over 35 years old can also be what causes premature labor. Pre-existing conditions like diabetes and high blood pressure may cause complications like preterm birth. However, with careful planning, many mothers 35 to 39 can have healthy babies.14

The prevalence of premature babies significantly increases past 40. For example, in 2013, 11 percent of mothers ages 30 to 39 had preterm births. As for mothers ages 40 to 44 and then 45 and older? About 16 and 25 percent had preemies, respectively.15

6. Stress

Stress may cause Premature Birth

There’s no doubt that stress takes a toll on the body. But did you know it can be what causes premature birth, too? The cortisol and epinephrine from stress increase the placental release of a hormone called corticotropin-releasing hormone. This induces estriol and prostaglandins, two markers of preterm delivery.

Psychological stress also enhances the inflammation of the immune system. This can make it hard for the body to support the pregnancy properly. It may go into a state of panic or shock because of chronic stress.

Plus, mothers who are stressed are more likely to cope with risky behaviors. This can be anything from unhealthy eating to alcohol. Needless to say, it’s essential for a mother to have a good support system.16

7. Closely Spaced Pregnancies

Close Spaced pregnancy Causes preterm labor

Failing to wait in between pregnancies is another premature birth cause. Your body needs to time to recover. The less time you wait, the greater your risk is for birthing a preemie.17

When you have a baby, your body loses a lot of nutrients. It takes time to build up your supply of protein, vitamins, and everything in between. At this point, the body barely has enough to support you – let alone another baby. That’s why you need to focus on restoring those levels.

Your vaginal canal also needs time to rest. Remember, it just went through a lot of stress. The bacterial balance also needs to become balanced again, especially if you had vaginal infections.

If you want to have another baby, wait at least 18 months.18 This will give you time to heal your body. Keep in mind that your supply of nutrients is the most important factor of a baby’s health. Without enough time to recover, a preterm birth is highly likely.19

8. Alcohol And Cigarettes

Alcohol and smoking Causes Premature Baby

Drinking alcohol and smoking cigarettes are some of the most preventable reasons for preterm delivery. These substances are poisonous for both you and the baby. And if you want to have a healthy birth, it’s crucial to think about these lifestyle choices.

Specifically, smoking cigarettes is linked to low birth weight, placental problems, and death. About 13 percent of pregnant women in the United States still smoke, unfortunately. The good news? If you quit before getting pregnant, there’s no risk for premature birth from smoking.20

Don’t forget about secondhand smoking, though. This can still be dangerous!

As for alcohol? Having more than one drink per day is linked to preterm delivery. However, there is no safe amount when you’re pregnant. Even drinking when you’re 4 to 6 weeks pregnant can cause problems. Brain damage, birth defects, and fetal alcohol spectrum disorders are also possible.21

References   [ + ]

1, 12. Bhattacharya, Sohinee, Edwin Amalraj Raja, Eider Ruiz Mirazo, Doris M. Campbell, Amanda J. Lee, Jane E. Norman, and Siladitya Bhattacharya. “Inherited predisposition to spontaneous preterm delivery.” Obstetrics & Gynecology 115, no. 6 (2010): 1125-1133.
2. Preeclampsia. MedlinePlus.
3. HELLP Syndrome. American Pregnancy Association.
4. Preterm Labor: Symptoms, Risks, and Treatment. American Pregnancy Association.
5. Preterm Labor. MedlinePlus.
6. Bacterial Vaginosis During Pregnancy. American Pregnancy Association.
7. Behrman, Richard E., and Adrienne Stith Butler. “Biological pathways leading to preterm birth.” (2007).
8, 9. Bhattacharya, Sohinee, and Siladitya Bhattacharya. “Effect of miscarriage on future pregnancies.” (2009): 5-8.
10. Complications In A Multiples Pregnancy. American Pregnancy Association.
11. Twins at Premature Birth. University of Rochester Medical Center.
13, 15. Preterm Births. Child Trends.
14. Pregnancy after 35. March of Dimes.
16. Behrman, Richard E., and Adrienne Stith Butler. “Biological pathways leading to preterm birth.” (2007).
17. How long should you wait before getting pregnant again? March of Dimes.
18. How long should you wait before getting pregnant again? March of Dimes.
19. King, Janet C. “The risk of maternal nutritional depletion and poor outcomes increases in early or closely spaced pregnancies.” The Journal of nutrition 133, no. 5 (2003): 1732S-1736S.
20. Behrman, Richard E., and Adrienne Stith Butler. “The Role of Environmental Toxicants in Preterm Birth.” (2007).
21. Alcohol during pregnancy. March of Dimes.

Disclaimer: The content is purely informative and educational in nature and should not be construed as medical advice. Please use the content only in consultation with an appropriate certified medical or healthcare professional.