Preterm Labor: Causes, Risk Factors, Symptoms, Complications, Prevention

A normal pregnancy lasts for about 40 weeks, with most pregnant women going into labor around the 40th week.1 However, it is possible for some women to go into labor a little earlier than expected. This is known as preterm labor, and it is characterized by experiencing contractions that start to open up the cervix before you reach the 37th week of pregnancy.2

Preterm labor can cause premature birth, which may pose many risks to the baby. Premature babies usually require additional care after birth and may also end up having long-term health problems that continue to affect them throughout their lives. It is important to know that the earlier in the pregnancy a baby is born, the more likely it is that the baby will experience some type of physical and mental disabilities.3

It is estimated that around 12 percent of all pregnancies can develop preterm labor. While the cause of preterm labor cannot always be determined, but there are various risk factors that are known to increase the chances of an early onset of labor.

What are the Causes & Risk Factors for Preterm Labor?

There is no way of really knowing whether a pregnant woman is going to experience preterm labor or not. Any pregnant woman can go into preterm labor and give birth to a premature baby, even after doing everything right during the duration of the pregnancy. However, there are certain risk factors that make it more likely for some women to go into preterm labor and give birth earlier than expected. These risk factors include:4

  • Multiple gestation – having more than one baby in the womb.
  • Having a history of premature birth
  • Infection
  • Experiencing vaginal bleeding in the middle of the pregnancy
  • Problems with the cervix, like a shortened cervix
  • Problems with the uterus
  • Drug and alcohol use before and during the pregnancy
  • Certain genetic conditions
  • Polyhydramnios – a condition in which there is an excessive amount of amniotic fluid surrounding the baby
  • Being very underweight or overweight before getting pregnant
  • Having underlying health conditions like diabetes, blood clotting disorders, high blood pressure, preeclampsia, or infections before pregnancy
  • Being pregnant with a baby that has congenital disabilities
  • Smoking
  • Being pregnant with a baby conceived with in vitro fertilization
  • Getting pregnant too soon after having a baby
  • Stressful life events, including the death of a loved one
  • Age of the mother, both too young and too old
  • Non-Hispanic, Black race and ethnicity
  • Limited or no access to prenatal care

It is important to remember that most women with these risk factors may still go on to carry their pregnancy to the full 40 weeks. However, if you are aware of your risk, you should let your doctor know so that you can be thoroughly evaluated and closely monitored by the doctor throughout the duration of your pregnancy.

What are the Symptoms of Preterm Labor?

It is important to know the warning signs of preterm labor so that you can stop it. Acting fast to halt preterm labor can make a massive difference to the health of the mother and the baby. You need to call your doctor or midwife immediately if you experience any of the following signs and symptoms:5,6

  • Contractions that come every 10 minutes or closer together
  • Backache – This type of backache typically begins in the lower back and might be constant or can come and go. The pain is not going to ease up even when you change your position or try something else for comfort.
  • Cramping or pain in the lower abdomen. They may even feel like menstrual cramps, or they may feel like the gas pains that tend to accompany diarrhea.
  • There is fluid leaking from the vagina.
  • Flu-like symptoms including nausea, vomiting, or diarrhea. Even in case of minor signs, you should still call your doctor.
  • If you are unable to tolerate liquids for over eight hours, it is important to see your doctor.
  • There is an increase in your normal vaginal discharge
  • There is increased pressure in your vagina or the pelvis.
  • Vaginal bleeding – Even light vaginal bleeding needs to be taken seriously.

Some of these symptoms can often be challenging to tell apart from the typical symptoms of being pregnant, especially symptoms like backache. However, when you are pregnant, you cannot be too cautious. It is essential that you take any such warning signs and symptoms immediately checked out.7

Are There Any Complications of Preterm Labor?

The biggest complication of preterm labor is delivering a preterm or premature baby. This can lead to a number of health problems for the baby, including:

  • Low birth weight
  • Breathing difficulties
  • Vision problems
  • Underdeveloped organs, especially the lungs and the stomach
  • Babies born prematurely also have a much higher risk of being born with learning disabilities, cerebral palsy, behavioral problems, and attention deficit hyperactivity disorder (ADHD).8,9,10
  • Checking for Contractions – Necessary for Spotting Preterm Labor
  • Recognizing the signs of preterm labor is most critical to taking steps to stop labor, if possible. Contractions are the biggest sign that you are going into labor, and checking for contractions in time is key to spotting early labor. Here’s how you can check for contractions:
  • Place your fingertips on your abdomen.
  • If you feel any tightening and softening of the uterus, it is a sign of a contraction.
  • It is important to time your contractions. Takedown the time when a contraction begins and also the time what is the time when the next contraction starts.

It is important that you inform your doctor and try to stop these contractions. You can do this in the following way:

  • Get off your feet.
  • Change your position
  • Drink two to three glasses of water.
  • Try to relax
  • Stay calm

If you continue to experience contractions every 10 minutes or more often, it is important to let your doctor know. If you find your symptoms getting worse, or if you start having severe pain that does not go away, seek medical help immediately as these could be signs that you are having a miscarriage.11

Not all contractions are signs of preterm labor. Remember that pregnant women often have harmless false labor known as Braxton Hicks contractions. During this also you will feel like your uterus is contracting.12,13 However, these are generally erratic, the contractions do not get closer together, and they will stop when you rest or move around. These types of contractions do not signal the onset of preterm labor. If you are not sure about what type of contractions you are experiencing, it is safer to seek medical help.14

If you feel the need to go to the hospital, it is probably best to go rather than second guess yourself. If, after hearing your symptoms, your doctor or midwife suspects that you might be going into premature labor, they will tell you to come to the hospital right away. Once you reach the hospital, your doctor/midwife will do the following:

  • The nurse on duty will take down your medical history, including information about what all medications you have been on during pregnancy.
  • Your pulse, temperature, and blood pressure will be checked.
  • Put a fetal heart monitor on your abdomen to keep monitoring the baby’s heart rate and your contractions.
  • Run a swab for fetal fibronectin, which is used to help predict the risk of having a preterm delivery.
  • Do a physical examination to check your cervix to see if it has started opening.15

If you are diagnosed with preterm labor, you may need immediate treatment, which may include:16

  • Medicines to relax the uterus in an attempt to stop labor
  • Medicines to speed up the development of the baby’s lungs.
  • Intravenous fluids
  • Antibiotics
  • Admit you to the hospital

If your doctor/midwife determines that your cervix is continuing to dilate and your labor cannot be stopped, they will start making preparations to deliver the baby.

However, if your doctor says you are not in preterm labor, they will allow you to go home. There is a popular myth that bed rest can help prevent preterm labor. However, studies have shown that bed rest is not able to prevent preterm birth and can, in fact, has its own risks as well.17

Is It Possible To Prevent Preterm Labor?

There is no way to guarantee that you can prevent preterm labor. However, there are several things you can do to ensure you reach a healthy and full-term pregnancy. These include:

  • Keep Up With Your Prenatal Care: Prenatal visits are essential in ensuring you have a healthy and safe pregnancy. These visits will help your doctor monitor your health and the baby’s health, especially if you have a high-risk pregnancy. Make sure to mention any signs and symptoms that are a cause of concern. If there is a history of preterm labor in your family, or if you have had a premature delivery in the past, it is important to let your doctor know. If you develop any symptoms of preterm labor, immediately call your doctor. If your doctor is able to stop the labor, you will still need to continue seeing them more often than before until your delivery.
  • Maintain A Healthy And Well-Balanced Diet: A healthy pregnancy outcome is closely linked with good nutrition – for both the mother and the baby. Try to eat a nutritious and well-balanced diet that includes plenty of fresh fruits and vegetables, whole grains, and healthy fats. Research has shown that a diet high in polyunsaturated fatty acids (PUFAs) is linked with a lower risk of preterm birth. PUFAs are commonly found in fish like mackerel, herring, trout, and albacore tuna; seed oils like soybean oil and flaxseed oil; nuts like walnuts; and seeds like flax seeds and sunflower seeds.18
  • Manage Any Underlying Chronic Conditions: Some types of health conditions, like high blood pressure, diabetes and obesity, are known to increase the risk of preterm labor significantly. Work with your doctor to ensure any such chronic health conditions are under control before and during your pregnancy.
  • Be Cautious If Using Reproductive Technologies: If you are planning on using assisted reproductive technology (ART) to become pregnant, it is important to exercise caution. Consider and plan in advance how many embryos you want to be implanted. Remember that multiple pregnancies carry a much higher risk of going into preterm labor.19

If your doctor determines that you could be at a high risk of preterm labor, they will recommend certain additional steps you should be taking to lower this risk. You will also be closely monitored during the entire period of your pregnancy to minimize the chance of any complications.

References:

  1. Alexander, J.M., McIntire, D.D. and Leveno, K.J., 2000. Forty weeks and beyond: pregnancy outcomes by week of gestation. Obstetrics & Gynecology, 96(2), pp.291-294. Challis, J.R., Lye, S.J., Gibb, W., Whittle, W., Patel, F. and Alfaidy, N., 2001. Understanding preterm labor. Annals of the New York Academy of Sciences, 943(1), pp.225-234.
  2. Newton, E.R., 2005. Preterm labor, preterm premature rupture of membranes, and chorioamnionitis. Clinics in perinatology, 32(3), pp.571-600.
  3. Roberts, W.E., Morrison, J.C., Hamer, C.H.E.R.Y.L. and Wiser, W.L., 1990. The incidence of preterm labor and specific risk factors. Obstetrics and gynecology, 76(1 Suppl), pp.85S-89S.
  4. Katz, M., Goodyear, K. and Creasy, R.K., 1990. Early signs and symptoms of preterm labor. American journal of obstetrics and gynecology, 162(5), pp.1150-1153.
  5. Iams, J.D., 2003. Prediction and early detection of preterm labor. Obstetrics & Gynecology, 101(2), pp.402-412.
  6. Lockwood, C.J., 1995. The diagnosis of preterm labor and the prediction of preterm delivery. Clinical obstetrics and gynecology, 38(4), pp.675-687.
  7. Lahat, A., Van Lieshout, R.J., Saigal, S., Boyle, M.H. and Schmidt, L.A., 2014. ADHD among young adults born at extremely low birth weight: the role of fluid intelligence in childhood. Frontiers in Psychology, 5, p.446.
  8. Nelson, K.B., 2008. Causative factors in cerebral palsy. Clinical obstetrics and gynecology, 51(4), pp.749-762.
  9. Browne, J.V., 2003. New Perspectives on Premature Infants and Their Parents. Zero to Three (J), 24(2), pp.4-12.
  10. Goepel, E., Ulmer, H.U. and Neth, R.D., 1988. Premature labor contractions and the value of serum ferritin during pregnancy. Gynecologic and obstetric investigation, 26(4), pp.265-273.
  11. Raines, D.A. and Cooper, D.B., 2017. Braxton Hicks Contractions.
  12. Reynolds, S.R.M., 1968. The uses of Braxton Hicks contractions. Obstetrics & Gynecology, 32(1), pp.134-140.
  13. Mulder, E.J.H. and Visser, G.H.A., 1987. Braxton Hicks’ contractions and prolonged uterine contractions in relation to fetal behaviour. European Journal of Obstetrics and Gynecology and Reproductive Biology, 26(2), pp.197-198.
  14. Iams, J.D., Paraskos, J., Landon, M.B., Teteris, J.N. and Johnson, F.F., 1994. Cervical sonography in preterm labor. Obstetrics and gynecology, 84(1), pp.40-46.
  15. Iams, J.D., 2003. Prediction and early detection of preterm labor. Obstetrics & Gynecology, 101(2), pp.402-412.
  16. Fox, N.S., Gelber, S.E., Kalish, R.B. and Chasen, S.T., 2009. The recommendation for bed rest in the setting of arrested preterm labor and premature rupture of membranes. American journal of obstetrics and gynecology, 200(2), pp.165-e1.
  17. Chen, C.Y., Chen, C.Y., Liu, C.C. and Chen, C.P., 2018. Omega-3 polyunsaturated fatty acids reduce preterm labor by inhibiting trophoblast cathepsin S and inflammasome activation. Clinical science, 132(20), pp.2221-2239.
  18. Shevell, T., Malone, F.D., Vidaver, J., Porter, T.F., Luthy, D.A., Comstock, C.H., Hankins, G.D., Eddleman, K., Dolan, S., Dugoff, L. and Craigo, S., 2005. Assisted reproductive technology and pregnancy outcome. Obstetrics & Gynecology, 106(5 Part 1), pp.1039-1045.

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