Causes of premature birth blog and the reasons why they occur.

Causes of Premature Birth and Why it Happens

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Premature Birth Causes: Learn and Understand these Conditions

You never expect to have complications when you are pregnant.

You expect to have a “regular” pregnancy and go full term and bring your baby home.

But this is not the case for some moms. 🙁

And this was not the case for me as well.

I never thought I would have a premature birth and I would have to leave my baby in the hospital.

The cause of my premature birth was placental insufficiency ( placenta wasn’t doing it’s job to feed and grow my baby).

At 29wks, my doctors found a placenta problem and my son wasn’t growing.

He was born at 31 wks and was in the NICU.

As a NICU nurse, I understood why my baby was born premature and the complication I had.

But many moms who have a high-risk pregnancy and eventually have a preemie don’t understand the condition that caused them to have a preemie.

So in this blog, I’m going to explain what a high-risk pregnancy is and the common causes of premature birth.

My goal is for all pregnant moms to learn all about the common causes of preterm birth, so they understand and can advocate for themselves to receive the best care possible.

So lets get started!!!

Premature birth Causes and why it happens to many moms.

What is Considered a High-Risk Pregnancy?

A high-risk pregnancy is when the mom or baby has an increased chance of developing a health complication. Firstly, this is due to a health condition:

1.that is present before pregnancy (Ex: having diabetes, obesity before pregnancy)


2. develops a new health condition during pregnancy (Ex: preeclampsia, placenta problems, low amniotic fluid, PPROM)

You will be monitored very closely when you are considered a high risk pregnancy.

You will have more ultrasounds to make sure the baby is growing well and no problems are seen.

More lab tests are send including a urine sample to monitor for infections.

Depending on the country you live in, you might be followed at a special clinic for high risk moms.

Also, you might deliver at a hospital with a Level 3 NICU, in case your baby is born less than 28 wks.

Check out this blog post on the NICU levels of care and the criteria for it.

Usually when you are high risk with one pregnancy, you will be considered high risk in all future pregnancies.

This is because the health condition that you have might return in future pregnancies.

When you are high risk and closely monitored, any complication will be noticed earlier and steps can be taken to prevent you from having a preemie.

high risk pregnancy mom being monitored by her doctor.

Causes of High-Risk Pregnancy

I just want to make it clear that if you have a “high-risk pregnancy”, it is not guaranteed you will have a premature baby.

But the chances of having a premature baby are increased because the condition that made you high risk can cause the baby to come early.

There are many moms who are high risk and they have a full-term baby because they are closely monitored and receive proper medical treatment early on.

Once you are high risk, you are monitored more closely to treat your medical condition and prevent you from having a preemie.

There are many risk factors that can cause high risk pregnancies.

Some risk factors we can control and others we cannot control.

Below are the common risk factors that all moms should know about.


  • Poor Nutrition
  • Smoking
  • Drugs/Alcohol
  • Obesity/Underweight
  • Stress/unhealthy environment


  • Mothers age greater than 35 years old
  • High blood pressure
  • Diabetes
  • Infection anywhere (Ex. UTI, amniotic fluid, vaginal)
  • Placenta problems
  • Low amniotic fluid or too much amniotic fluid
  • Short cervix and/or opening of the cervix
  • Having a previous premature baby
  • Twins or Triplet pregnancy
  • A fall, car accident

There also many women that have premature babies and have no risk factors!!

They are healthy, young, first or second pregnancy, eat well, and exercise.

These premature births are the hardest for doctors and nurses to explain and understand.

And to this day, nobody really knows why these women end up going into premature labour.

Explore Parents stated that 30-40% of preterm births, with no risk factors, are caused by a genetic factor.

Many doctors and researchers continue to study the genetic link to preterm birth, so hopefully one day we can use this knowledge to help many parents.

Premature Birth Causes that are the Most Common


Preeclampsia happens after 20 wks.

Also, some moms can experience preeclampsia after giving birth.

Preeclampsia is when blood pressure is very high that there is damage to other cells and organs. This can lead to seizures or death if not treated!

We don’t really know why preeclampsia happens…

but we know that it’s connected to the abnormal development of the blood vessels of the placenta early on in the pregnancy.

It consist of 3 factors:

  1. New high blood pressure for the patient: this includes 2 readings of blood pressure equal to or higher than 140/90
  2. Protein in the urine: a sign of kidney damage-normally there should never be protein in the urine
  3. Damage to the liver and brain ⇨damage to liver leads to HELLP syndrome

HELLP Syndrome: It occurs in severe preeclampsia. The body is trying to repair itself because of the damage that happened. HELLP stands for:

H: HEMOLYSIS: rupturing of red blood cells. Red blood cells take oxygen and nutrients to tissues of the body

EL: ELEVATED LIVER ENZYMES: shows us that there is liver damage

LP: LOW PLATELETS: platelets are what stops the bleeding when you have a cut. In HELLP, the body is sending platelet to help the injury, but the platelets start to stick together at the injury site. This causes a blockage of blood flow to the organ.

Signs and symptoms of preeclampsia are:

  • High blood pressure
  • Protein in the urine
  • Swelling: increased swelling to hands, arms and legs, increased weight gain, trouble breathing
  • headache
  • vision problem
  • abdominal pain

Risk Factors:

  • first pregnancy
  • multiple pregnancies ex: twins or triplets
  • mothers older than 35 yrs old
  • having high blood pressure before pregnancy
  • diabetes
  • Obesity

It’s very important to monitor you if you have preeclampsia as it can be dangerous for you and your baby.

The best treatment is delivery of your baby.

If the baby is really premature, doctors will try to prolong the pregnancy through medications.

You will receive corticosteroid shots, to help mature your baby’s lung faster, in case a preterm delivery has to happen.

Until then, they will give you medications to bring your blood pressure down,

but if the blood pressure is not decreasing and your symptoms are not improving….

then the last resort is to deliver your baby to protect your life and your baby’s life.

Check out this blog post Preeclampsia Stories for more details on this condition and the how to prevent it.

Cervical Insufficiency/Incompetence Cervix

This problem is not known until you get pregnant.

The cervix is normally closed and long until you get to full-term… then it changes to being short and it slowly opens up during labour.

Cervical insufficiency is when your cervix starts to open up too early in your pregnancy and it’s short in length.

As the baby gets bigger, it pushes against your cervix and your cervix starts to open prematurely.

Cervical insufficiency is seen after 20 wks.

Signs and symptoms:

  • sometimes no signs are present
  • Usually, no pain or contraction is present
  • pelvic pressure
  • light bleeding
  • mild abdominal cramps

⚡Risk Factors⚡:

  • No one really knows why this happens and who is more of a risk for it.

This is why every mom gets a routine measuring of the cervix at 18 wks, to catch a short cervix.

It is usually caught on ultrasound or by the doctors via examination.

The solution is to put a stitch in (cervical cerclage) to keep the cervix closed for as long as possible and minimize physical activity.

There would be more ultrasounds and monitoring to make sure the stitch is working in keeping the cervix closed.

If doctors are not able to keep the cervix closed, then preterm delivery is considered.

    Placenta Insufficiency

    Placenta problems can happen with no explanation or it is a side effect of another condition, such as preeclampsia.

    The placenta is the life line of the baby; it provides oxygen, nutrients and removes the baby’s waste.

    Placenta insufficiency is when the placenta is not providing enough nutrients and oxygen for the baby to grow well.

    In other words, the placenta is not doing its job properly and the baby is struggling inside mom to grow.

    Signs and symptoms of placenta problem:

    • baby is measuring small for their age in ultrasounds
    • abnormal blood supply going to the baby, seen in ultrasounds
    • decreased movement of the baby on Non-stress test

    ⚡Risk Factors:⚡

    • usually the first sign of having preeclampsia

    With a placenta problem, doctors try to keep the baby in as long as possible and monitor through frequent ultrasounds.

    Some moms are hospitalized to be monitored and other moms can go home, but have to return to be monitored.

    Also a non-stress test machine is used to monitor heart rate and baby movements.

    I had this done 2 times a day for 2 wks before my son was born. [see below]

    Non stress test for a mom that has a high risk pregnancy
    hand of patient press the button of fetal non-stress test machine (NST)
    Non stress test being done on a mom who has a high risk pregnancy.

    Once doctors see the baby is very stressed and not doing well inside, then delivery of baby is considered.

    These babies are usually IUGR (intrauterine growth restricted) meaning they stopped growing inside their mom and are very small for their age.

    Their weight and size are very small, but they have big heads because their brain was still growing and getting blood supply.

    Preterm Premature Rupture of Membranes (PPROM)

    PPROM is when your water (the amniotic sac) breaks before 37 wks.

    The amniotic fluid protects the baby from bacteria, so once your water breaks, you have an increased chance of getting an infection.

    Also, without amniotic fluid, preterm labour may start.

    Signs & Symptoms:

    • None.. it just all of a sudden happens and its scary!

    Risk factors:

    • previous uterine infection
    • blunt trauma ie. fall or car accident
    • overstretching of the uterus or amniotic sac Ex: multiples, too much amniotic fluid (polyhydramnios)

    The most difficult part of PPROM is that it usually happens without any explanation or risk factors present.

    This is the hardest for alot of moms to accept because they don’t understand why it happened and you feel like you have no control of the situation.

    The treatment of PPROM is to decrease the chance of infection and prepare the baby for preterm birth.

    This includes:

    1. Hospital admission and frequent monitoring of mom and baby, so baby can stay inside for as long as possible
    2. Giving medications like magnesium sulphate to delay labour, so steroids & antibiotics can be given on time
    3. giving corticosteroid shots to mom to mature the baby’s lung faster, so they don’t need as much breathing support in the NICU after they are born.
    4. Antibiotics are given to prevent infection
    5. Consider inducing labour to decrease the risk of infection

    UTI/ any Infection

    Symptoms of a UTI or other infections can be easily missed by alot of pregnant moms, as problems with urinating can be a normal side effect of pregnancy.

    If signs are missed, a UTI can causes contractions.

    Signs and Symptoms includes:

    • needing to pee all of the time
    • When you sit down, no urine comes out
    • burning and pain with peeing

    Treatment is you need to give a urine sample to check for bacteria and other signs of infection.

    When the urine sample comes back positive, you will be given antibiotics that will stop the contractions.

    This is why getting treatment early is very important to prevent preterm labour.

    It’s harder to stop contractions if a UTI or another infection is left untreated.

    If you had received early treatment of antibiotics, but the contractions have not stopped, then there is something else going on and your doctor will do further testing.

    Placenta Abruption/Haemorrhage

    The placenta starts to detach from the uterus, which can cause lots of bleeding.

    So the uterus starts to contract to stop the bleeding, therefore labour is induced with these contractions.

    Also, if the placenta detaches from the uterus, it has lost its effectiveness and the baby can be distressed and lose oxygen.

    Signs and symptoms:

    • hemorrhage, which can be hidden or visible
    • abdominal pain/contractions
    • decreased baby movement
    • hard abdomen

    Risk Factors:

    • having preeclampsia
    • having uncontrolled high blood pressure throughout pregnancy
    • trauma to the abdomen
    • smoking/cocaine use
    • multiple pregnancies

    Treatment for placenta abruption depends on how far along the pregnancy is, how the baby is doing, how much bleeding is present.

    If mom and baby are stable, then blood transfusions can be given to keep them stable and monitor.

    If there is severe bleeding or the baby is not doing well, then an emergency c-section would occur.

    Final Thoughts on Premature Birth Causes

    I listed the most common causes of premature birth, but there are many other causes too.

    There are also many moms who have premature babies without any explanation of why it happened.

    This is the hardest situation as a health care provider to explain and it’s difficult for NICU parents to accept.

    Being high risk with your pregnancy is actually a blessing in disguise as problems can be found earlier and treated.

    Most of the causes I mentioned above have treatments that can be started early, so preterm birth can be avoided.

    So never give up hope of having a full term baby after you had a preemie!

    If you had a preemie, did you know the cause of your preterm birth? Comment Below

    If anything on my blog has helped you, please make sure to share the post, comment below the post and subscribe to my email list for more goodies.

    I would love to hear from you!

    Instagram: @nicunursefaith

    Preterm birth causes and why they happen. This photo shows a preterm baby in the NICU.

    Causes of Premature Birth and Why it Happens

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