What Causes Pregnancy Loss?

Overview of Miscarriage and Stillbirth

You have recently experienced a pregnancy loss.

Along with crushing sadness, there are many questions.

Was it something I did?

Could I have prevented this?

Why did this happen?

Whether your loss was early miscarriage, second-trimester loss, or stillbirth, you lost your baby. And the grief and need to understand is natural.

Pregnancy loss is medically complex. Causes vary depending on the stage of pregnancy.

Often, despite testing, no clear answer is found.

It is more common than many people realize.

In general, 20–25% of recognized pregnancies end in miscarriage, ectopic pregnancy, molar pregnancy, or stillbirth. In the United States, this affects close to one million families each year.

It's difficult to discuss a single cause of miscarriage, pregnancy loss or stillbirth in a simple way. There are many different causes for pregnancy loss and the causes are related to the stage of pregnancy in which the loss occurs.

You are not alone - even if it feels that way.

Abnormal Pregnancies

Ectopic and Molar Pregnancies

Ectopic Pregnancy

An ectopic pregnancy is when the fertilized egg implants somewhere other than the uterus, usually in the fallopian tube, less commonly in the stomach cavity, the ovaries or even the cervix.

Ectopic pregnancies are usually caused by a blockage in the fallopian tube, from scarring or infection. An ectopic pregnancy is not viable, can be life-threatening to the mother, and requires medical treatment.

Molar Pregnancy

A molar pregnancy is when, at the time of egg fertilization, abnormal tissue develops, rather than a normal fetus. A molar pregnancy is caused by genetic error at the time of fertiilzation.

Like an ectopic pregnancy, a molar pregnancy is not viable, can be life-threatening for the mother and requires medical treatment.

First Trimester Miscarriage (Before 12 Weeks)

During the first trimester, or before 12 weeks of gestation, as many as 40% of all pregnancies may end in miscarriage, often before the mother even knows she is pregnant.

First trimester miscarriage is most commonly caused by:

• chromosomal abnormality, meaning that there is something wrong with the developing baby’s chromosomes

  • 80% of the time, chromosomal abnormalities are random occurrences. Less commonly, chromosomal abnormalities can also be caused by one or both parents being a carrier for an abnormal chromosomal arrangement.

• Infections

  • If an infection caused the miscarriage, generally it is from an acute, one-time bacterial infection. Less often, a long-term illness or a compromised immune system in the mother can be the cause of infection.

• Hormonal problems

  • Imbalances in the thyroid, pituitary, adrenal, parathyroid glands or the ovaries can be chronic and cause hormonal imbalance.

• External lifestyle influences such heavy substance abuse (alcohol, smoking, drugs)

• Significant environmental toxin exposure, such as radiation,

  • Large amounts of radiation, such as from a reactor failure is dangerous to pregnancy.

• Severe maternal trauma

  • Depending on the severity, a car accident, or a fall, can be the cause of miscarriage. 25% of maternal trauma is due to domestic violence.

**Importantly:

• Everyday stress has not been linked to miscarriage

• Normal exposure to everyday electronics (computers, phones) has not been linked to miscarriage.

Second Trimester Miscarriage (13 - 19 Weeks)

Second trimester miscarriage is less common than first trimester miscarriage, occurring in 1 to 5 percent of pregnancies.

The causes for second trimester miscarriage are often:

• A chromosomal problem that actually occurred in the first trimester, but was undetected during normal first trimester screenings

  • 80% of the time, chromosomal abnormalities are chance occurrences. However, less commonly, chromosomal abnormalities can also be caused by one or both parents being a carrier for an abnormal chromosomal arrangement.

• Cervical Insufficiency

  • When a woman’s cervix has weakened because of genetic or surgical reasons and starts to open up during pregnancy.

• Infections

  • If an infection caused the miscarriage, generally it is from an acute, one-time bacterial infection. Less often, a long-term illness or a compromised immune system in the mother can be the cause of infection.

• External lifestyle influences such as heavy substance abuse (alcohol, smoking, drugs)

• Environmental toxin exposure, such as radiation

  • Large amounts of radiation, such as from a reactor failure is dangerous to pregnancy.

• Maternal Trauma

  • Depending on the severity, a car accident, or a fall, can be the cause of miscarriage. 25% of maternal trauma is due to domestic violence.

**Importantly:

• Everyday stress has not been linked to miscarriage

• Normal exposure to everyday electronics (computers, phones) has not been linked to miscarriage.

Stillbirth (After 20 Weeks)

When fetal death occurs after 20 weeks gestation, this tragedy is called a stillbirth. In the United States, a stillbirth occurs in about 1 in 200 pregnancies. Sometimes this is first diagnosed when the mother notices the baby moving around anymore. A visit to the doctor and an ultrasound test can detect whether or not the baby’s heart is still beating.

Sometimes it's never known what causes a stillbirth.

However, the most common causes are:

• Birth defects in the developing fetus due to chromosomal abnormalities

  • Often random and unpreventable

• Placental problems

  • Placenta problems can occur when, due to low hormonal levels, there's poor attachment to the inside of the uterus. This is called placenta previa or placenta accreta.

• Umbilical cord accidents

  • An umbilical cord accident means that something happened which interfered with the flow of blood to the fetus, such as a kink or a ruptured blood vessel.

• Infections

  • If an infection caused the miscarriage, generally it is from an acute, one-time bacterial infection. Less often, a long-term illness or a compromised immune system in the mother can be the cause of infection.

• Maternal health problems, such as uncontrolled diabetes

  • In order to have a healthy pregnancy, maternal health problems such as diabetes, must be continuously monitored and controlled diligently.

• Maternal trauma

  • Depending on the severity, a car accident, or a fall, can be the cause of miscarriage. 25% of maternal trauma is due to domestic violence.

The Question Beneath the Question

Most parents are not only asking, What caused this?

They are asking, Was it my fault?

In the vast majority of pregnancy losses, the answer is no.

Pregnancy is biologically intricate. Early development involves rapid cell division, genetic replication, hormonal orchestration, and placental formation. Many losses occur because something in that process didn't develop in a sustainable way.

Grief searches for control. Blame can feel easier than randomness.

But randomness is often the truth.

If You Are Trying Again

If you are considering pregnancy after loss, medical consultation is wise.

Testing may or may not yield answers.

Many women go on to have healthy pregnancies after miscarriage or stillbirth.

Your body is not broken.

Your grief does not mean you are weak.

Your questions are part of loving deeply.

Related Articles

• Talking to Your Child About Infant Loss

• Book Review: We Were Gonna Have a Baby, But We Had an Angel Instead

Sources:

Douglas, A. & Sussman, J.R. (2000). Trying again: A guide to pregnancy after miscarriage, stillbirth and infant loss. Lanham, Maryland: Taylor Trade Publishing

Michels, T.C, and TIU, A.Y. (2007). American Family Physician, Nov 1, 76(9), 1341-1346. Second Trimester Pregnancy Loss

March of Dimes (2011). http://www.marchofdimes.com/baby/loss_stillbirth