Preterm (Premature) Labor: Causes, Signs & How To Prevent?

Preterm (Premature) Labor

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Did you know? An estimated 15 million babies are born preterm every year across the world. This comes down to more than 1 in 10 babies. Not just that. Preterm birth is the predominant reason for infant mortality (1).

Such worrisome statistics make it imperative for every pregnant woman to be aware of the problem so that she can seek timely medical intervention, if necessary. Therefore, Momjunction explains the reasons for premature labor, its risk factors, treatment options available, and preventive measures you may take.

What Is Preterm Labor?

Preterm labor occurs when regular contractions start before 37 weeks of pregnancy followed by cervical dilation. It can be categorized based on when it happens:

  • Less than 28 weeks — extremely preterm
  • 28 to 32 weeks — very preterm
  • 32 to 37 weeks — moderate to late preterm

If the baby’s birth happens between the 20th and 37th week, then it is termed preterm birth. Needless to say, the earlier the labor, the more problematic it is.

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What Are The Causes Of Preterm Labor?

Let’s see the reasons here (2):

  1. Spontaneous preterm labor: It is an unplanned delivery that happens before the 37th week of pregnancy. While the actual reasons for such preterm labor are not known, an infection or inflammation might trigger it.
  1. Medically indicated preterm birth: In case of a medical condition like preeclampsia, the doctor recommends preterm delivery by inducing labor.

However, if there are no serious medical issues, the doctor might use additional interventions to keep the baby inside the womb for as long as possible. In such cases, the health of the mother and the baby is closely monitored.

If it is not possible to hold the pregnancy for long, the doctor may consider giving steroids to mature the organs of the fetus.

  1. Non-medically indicated (elective) preterm delivery: It is the labor induced or a c-section carried out even when there is no medical emergency. Such preterm delivery is usually not recommended. Studies have shown that babies delivered during the 37th and 38th weeks by inducing labor many have poor health outcomes compared to those delivered during the 39th week or later (3).

Preterm labor can happen at any time, and you may not be prepared for that. But you can know if you are at risk.

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[ Read: Progesterone For Preterm Labor ]

Who Are At Risk Of A Preterm Labor?

You are at a higher risk if you relate to one or more of the below factors (4):

  • Being overweight or underweight before pregnancy
  • Improper prenatal care
  • Physically stressful work
  • Smoking, alcohol consumption or illicit drug intake during pregnancy
  • Maternal health issues like high diabetes, blood pressure, preeclampsia, or thyroid
  • Certain birth defects in the baby
  • In-vitro fertilization pregnancy
  • Twin or multiple pregnancies
  • Blood clotting problems
  • Excess or insufficient amniotic fluid
  • Vaginal infections like bacterial vaginosis and trichomoniasis, chlamydia infection, nongenital tract infection (asymptomatic bacteriuria, pneumonia, appendicitis)
  • Urinary tract infections and sexually transmitted infections
  • Uterine rupture in the previous C-section delivery
  • Removal of uterine fibroid
  • Reproductive organ abnormalities like short cervix or shortening of the cervix during the second trimester instead of the third trimester
  • Placenta previa
  • A history of premature birth
  • Getting pregnant within six months of last pregnancy
  • Women younger than 18 and older than 35 years of age
  • Lifestyle and environmental factors
  • Exposure to environmental pollutants
  • Domestic violence, sexual, physical, emotional abuse, and lack of social support

The more the risk factors, the higher is your chance of having preterm labor; and this is not good for the baby.

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[ Read: Anemia During Pregnancy ]

What Are The Complications In Preterm Babies?

The US Centers for Disease Control and Prevention identifies the below health risks for babies born preterm:

  1. Low birth weight of less than 2,500g or 5.5lb
  1. Breathing difficulties, including:
    a. Respiratory distress syndrome/ hyaline membrane disease, a condition that arises due to the lack of surfactants in the lungs that makes the air sacs close
    b. Chronic lung disease caused due to tissue injury in the long-term
    c. Air leakage out of the lung spaces
    d. Incomplete lung development
    e. Stopped breathing or apnea
  1. Underdeveloped organs and vision problems
  1. Higher risk of learning disabilities
  1. Behavioral problems
  1. Temperature instability — the inability to regulate body temperature due to low body fat
  1. Cardiovascular problems such as:
    a. Patent ductus arteriosus (PDA), a condition that inhibits blood supply to the lungs
    b. Too high or low blood pressure
    c. Low heart rate (often occurs with apnea)
  1. Blood and metabolic conditions that include:
    a. Anemia, which may require blood transfusion
    b. Jaundice due to underdeveloped liver and immature gastrointestinal function
    c. Very low or high level of minerals like calcium and substances like glucose in the blood
    d. Immature kidney function
  1. Gastrointestinal complications, including:
    a. Feeding difficulties – inability to suck and swallow
    b. Poor digestion
    c. Necrotizing enterocolitis (NEC), a serious intestinal disease
  1. Neurological complications:
    a. Intraventricular hemorrhage (bleeding inside the brain)
    b. Periventricular leukomalacia, a condition that causes softening of brain tissues around the ventricles, which contain cerebrospinal fluid
    c. Poor muscle tone
    d. Seizures caused by bleeding inside the brain
    e. Retinopathy of prematurity (ROP) – causes abnormal growth of the blood vessels in the retina, which can result in the detachment of retina from the back of the eye causing blindness
  1. Infections that might require antibiotic treatment

The chances of these complications may be reduced if the signs of preterm are recognized and the problem diagnosed in time.

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[ Read: Types Of Contractions ]

What Are The Symptoms Of Preterm Labor?

According to the American College of Obstetricians and Gynecologists, the below signs indicate premature labor:

  • Increased vaginal discharge
  • Change in the type of discharge i.e., watery, mucus, or bloody (discharge in pink or tinged with blood)
  • Vaginal bleeding or spotting
  • Pain in the lower abdomen
  • Abdominal cramps with or without diarrhea
  • A pressure felt in the pelvic area
  • Lower back pain
  • Frequent, painless uterine contractions
  • Water break (with a gush or trickle of fluid)

Some of the symptoms, such as vaginal bleeding and contractions might look similar to the ones you have been having throughout your pregnancy.

  • However, vaginal bleeding is different if it has a tinge of pink or red color in it, and is accompanied by water break or contractions.
  • The labor contractions are different from Braxton Hicks in that the later are short-lived and reduce, while the former gradually increase in frequency and intensity.

You do not have to panic every time you have false contractions or spotting. But if you experience any of these symptoms, then seek a diagnosis.

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How Is Preterm Labor Diagnosed?

The below tests and procedures help determine if you are having a preterm labor (5):

  1. A pelvic exam to understand uterus: It helps the doctor know the thickness of the uterus and the size and position of the baby. It also helps to evaluate if the cervix has dilated to 10cm in the case of a water break, and check for placenta previa (placenta covering the cervix).
  1. Ultrasound to check the baby’s size: It helps determine the size, weight, age, and position of the baby as well as the level of amniotic fluid around the baby.
  1. Uterine monitoring: It is done using tocometer to measure the duration and spacing between your contractions.
  1. Lab tests for infections: They include a swab test of the vaginal secretions to check for any infections and fetal fibronectin. Fetal fibronectin is a protein secreted by the uterus and acts as glue to attach the fetal sac to the lining of the uterus. The disintegration of this glue could indicate labor.

If the diagnosis hints at a possible preterm delivery, then the doctor will try to prolong the pregnancy through various treatment methods.

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[ Read: Risks Associated With A Premature Baby ]

How Is Preterm Labor Managed?

The treatment of preterm delivery depends on its cause and after weighing the pros and cons of delaying the labor.

If preterm labor starts before 34 weeks of pregnancy, then the doctor will recommend hospitalization, and you will be put on medications (6):

  1. Antibiotics in case of water break: If preterm labor is associated with infection or inflammation, and leads to premature rupture of membranes (water break), the doctor will prescribe the antibiotic erythromycin.
  1. Corticosteroids for lung maturity: The steroid injection is given between 24 and 34 weeks of pregnancy to speed up the process of your baby’s lung maturity. This medication could also be recommended during the 23rd week or up to the 36th week of pregnancy if the doctor suspects that you might deliver in the next seven days.
  1. Tocolytics to control contractions: The medication is given to temporarily stop the contractions of preterm labor. This provides the window for the steroids or other drugs to act. Tocolysis is done using various drugs such as Nifedipine that prevents the calcium influx required for myometrial cell contraction, or Atosiban that controls the activity of oxytocin.

Tocolysis is not recommended for women with pregnancy-induced high blood pressure.

Betasympathomimetic drugs ritodrine, terbutaline and salbutamol are commonly used to inhibit uterine contractions. But studies have found that calcium channel blockers (Nifedipine) are more effective than betasympathomimetic drugs (7).

  1. Cervical cerclage: In pregnant women with a short or weak cervix, a surgical procedure called cervical cerclage is carried out to control the chances of preterm labor. This procedure involves stitching the cervix closer with strong sutures, and is recommended if:
  • You are less than 24 weeks pregnant
  • You had a premature delivery previously
  • The cervical length is less than < 25mm

These treatments may or may not prolong your pregnancy. But if you follow some preventive measures, your chances of having preterm labor might come down.

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[ Read: Steroids During Pregnancy ]

What Are The Preventive Measures For Preterm Labor?

You may try the below measures to prevent preterm labor and have a healthy pregnancy:

  • Adopt a healthy lifestyle. Avoid smoking and taking illicit drugs during pregnancy.
  • Do not take any medications without your doctor’s permission.
  • Have a decent gap between two pregnancies because a spacing of less than six months can increase the risk of preterm labor.
  • If you are in a high-risk zone, the doctor may recommend a weekly shot of progesterone hormone, known as 17 alpha-hydroxyprogesterone caproate (Makena) (8).
  • Stressful physical activities can also lead to preterm labor. Therefore, talk to your healthcare provider before starting on such activities.
  • Keep tracking your levels regularly if you have gestational diabetes or high blood pressure.
  • Have control over negative emotions such as anxiety.
  • If you have contractions, then drink a lot of fluids. They could be false contractions, so wait for some time to see if the contractions continue.

Do not miss any prenatal visits. If you notice any peculiar signs or symptoms, then tell your doctor about them. This will help them foresee preterm labor.

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What To Expect During Your OB Visit

In case of any symptoms or signs of preterm labor make sure to inform your doctor right away. Here is what might happen during the visit.

What to expect from the doctor?

Your doctor might ask you some questions such as:

  • When did you notice the signs of contraction?
  • Do you feel any contractions now?
  • How many contractions did you feel in an hour?
  • Did you notice any change in the vaginal discharge?
  • Are you suffering from fever or any infectious disease?
  • Do you have a history of miscarriages or cervical or uterine surgeries?
  • Do you smoke? If so, how much?

How can you plan your appointment?

  • Call the hospital and ask if you can meet the doctor immediately.
  • Make sure to take your partner or a friend along. In case of any signs of preterm labor, you might not be in a state to focus on what the doctor is saying. The person accompanying you can take down all the information.
  • Jot down all the queries that you have in mind and get them cleared during the visit.

Here are some basic questions you can ask the doctor:

  • Am I in labor?
  • What can I do to prolong my pregnancy?
  • What treatments could help my baby if I have preterm labor?
  • What are the symptoms I should look out for?
  • How soon should I contact the hospital?
  • What are the possible risks if my baby is born prematurely?

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[ Read: Signs Of Labor ]

Preterm labor is unpredictable but you can read the cues and take preventive measures. The doctor will make every effort to delay the delivery so that the baby can grow as much as possible. Therefore, do not skip any important health details during your regular visit to your OB/GYN. Tell them about your lifestyle, past pregnancies, any health issues you have and get your doubts clarified.

Do you have an experience to share? You may do it in the comments section below.

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