Originally posted January 3, 2017.
Overview of Pregnancy Loss
You have recently experienced a pregnancy loss. You have many questions along with crushing sadness. Perhaps you miscarried, or perhaps your baby was stillborn. Whichever it may be, you lost your baby prior to birth. You are wondering if there was something you could have done to prevent it. You want to know more about what causes this to happen.
It is 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.
In general, 20 – 25% of recognized pregnancies end in miscarriage, ectopic pregnancy, molar pregnancy, or stillbirth. In the United States, that makes about one million women a year experiencing pregnancy loss. It is more common than you might think.
What are Abnormal – Ectopic and Molar – Pregnancies
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.
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.
Neither an ectopic nor a molar pregnancy is viable for the fetus and both are dangerous for the mother.
Miscarriage During the First Trimester
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 chance occurrences. However, 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 as smoking or substance abuse
Alcohol, smoking and drug abuse all increase the chances of miscarriage.
Environmental toxin exposure, such as radiation, paint fumes, cleaning fluids, hair dyes, etc
Normal amounts of radiation exposure, such as to computers and cell phones, have not been linked to miscarriage, However, larger amounts of radiation, such as from a reactor failure is dangerous to pregnancy.
Exposure to lead-based toxins can be dangerous to the fetus. Exposure to chemicals used in hair treatments have not been implicated in miscarriage unless working with them daily and in large quantities.
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.
Miscarriage During the Second Trimester
Second trimester miscarriage, from around 13 to 19 weeks gestation, 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, chromosomal abnormalities can also be caused by one or both parents being a carrier for an abnormal chromosomal arrangement.
Cervical Insufficiency
This is 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 smoking or substance abuse
Environmental toxin exposure, such as radiation, paint fumes, cleaning fluids, hair dyes, etc
Normal amounts of radiation exposure, such as to computers and cell phones, have not been linked to miscarriage, However, larger amounts of radiation, such as from a reactor failure is dangerous to pregnancy.
Exposure to lead-based toxins can be dangerous to the fetus. Exposure to chemicals used in hair treatments have not been implicated in miscarriage unless working with them daily and in large quantities.
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.
What Causes Second Trimester Miscarriage?
Stillbirth
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. The most common cause for stillbirth is Sometimes it is never known what causes a stillbirth. However, the most common causes are:
Birth defects in the developing fetus due to chromosomal abnormalities
80% of the time, chromosomal abnormalities are chance occurrences. However, chromosomal abnormalities can also be caused by one or both parents being a carrier for an abnormal chromosomal arrangement.
Placental problems
Placenta problems can occur when, due to low hormonal levels, there is 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 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.
References:
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