Spontaneous abortion is the medical term for a miscarriage, the natural loss of a pregnancy before 20 weeks of gestation. It is not an elective procedure. The term appears frequently in medical records, lab results, and clinical conversations, which can be confusing or alarming if you’re not expecting it. About 10 to 13% of all recognized pregnancies end in miscarriage, and roughly 80% of those losses happen within the first 12 weeks.
Why Doctors Use the Term “Abortion”
In medical terminology, “abortion” simply means the ending of a pregnancy before the fetus can survive outside the uterus. “Spontaneous” distinguishes a naturally occurring loss from an induced procedure. If you see this phrase on paperwork from your doctor or hospital, it refers to a miscarriage. Many healthcare providers are moving toward using “early pregnancy loss” instead, precisely because the older terminology causes unnecessary distress.
How Common It Is by Age
Miscarriage is one of the most common complications of pregnancy. A large Norwegian registry study tracking hundreds of thousands of pregnancies found that the risk is lowest for women aged 25 to 29, at about 10%. For women under 20, the rate is around 16%. The risk climbs steadily after 35: about 17% for women 35 to 39, jumping to 33% for women 40 to 44, and exceeding 50% for women over 45.
These numbers reflect recognized pregnancies only. Many miscarriages happen so early that a person never realizes they were pregnant, meaning the true rate is higher than any study can capture.
What Causes a Miscarriage
About half of all first-trimester miscarriages are caused by chromosomal abnormalities in the embryo. These are random errors that occur when cells divide during the earliest stages of development, not something either parent did or could have prevented. The embryo simply cannot develop normally, and the pregnancy ends on its own.
The other half involves a mix of factors that are often harder to pin down. Conditions like uncontrolled diabetes, thyroid disorders, uterine abnormalities, and certain immune system problems can increase the risk. Lifestyle factors such as smoking, heavy alcohol use, and significant caffeine intake also play a role. But in many individual cases, no specific cause is ever identified, which can be one of the hardest parts of the experience.
Types of Pregnancy Loss
Not every miscarriage looks or feels the same. Clinicians classify pregnancy loss into several categories based on what’s happening physically:
- Threatened miscarriage: Bleeding and cramping occur, but the pregnancy may still be viable. An ultrasound still shows a heartbeat.
- Missed miscarriage: The embryo or fetus has stopped developing, but the body hasn’t recognized the loss yet. There may be no bleeding or cramping at all. This type is often discovered during a routine ultrasound.
- Incomplete miscarriage: The body has begun to pass pregnancy tissue, but some tissue remains in the uterus.
- Complete miscarriage: All pregnancy tissue has passed from the uterus on its own.
Signs and Symptoms
The most common sign is vaginal bleeding, which can range from light spotting to heavy flow with clots. Cramping or pain in the lower abdomen or back often accompanies the bleeding and can feel similar to strong menstrual cramps. Some people also pass tissue or fluid from the vagina.
It’s worth noting that light spotting in early pregnancy is common and doesn’t always mean a miscarriage is happening. Up to 25% of pregnant people experience some first-trimester bleeding and go on to have healthy pregnancies. Heavy bleeding with clots, severe cramping, or a sudden disappearance of pregnancy symptoms like nausea and breast tenderness are more concerning signs.
With a missed miscarriage, there may be no obvious symptoms at all. The loss is only discovered when a heartbeat cannot be detected on ultrasound.
How a Miscarriage Is Confirmed
Ultrasound is the primary tool for confirming a pregnancy loss. Specific findings that indicate a nonviable pregnancy include an embryo measuring 7 mm or larger with no heartbeat, or a gestational sac measuring 25 mm or larger with no embryo visible inside. When the picture isn’t clear from a single scan, your provider will typically schedule a follow-up ultrasound one to two weeks later to look for changes.
Blood tests that measure pregnancy hormone levels can also help. In a healthy pregnancy, these levels roughly double every two to three days in the early weeks. Levels that plateau, rise abnormally slowly, or drop suggest the pregnancy is not progressing. In some situations, providers use a combination of ultrasound and blood work over several days to reach a definitive answer, particularly when the pregnancy is very early.
Treatment Options
Once a miscarriage is confirmed, there are three main approaches. Which one is right depends on how far along the pregnancy was, what type of loss it is, and personal preference.
Expectant Management
This means waiting for the body to pass the pregnancy tissue naturally, without medical intervention. It avoids medication and procedures but can take days to weeks, and the timing is unpredictable. Bleeding tends to last longer with this approach than with the other options. About 40% of people who choose expectant management ultimately need a surgical procedure because the tissue doesn’t pass completely on its own.
Medication
A medication can be given vaginally to help the uterus contract and pass the pregnancy tissue more quickly. This approach is faster than waiting but still involves significant cramping and bleeding, usually over several hours to a few days. About 30% of people who take medication still end up needing a procedure afterward for tissue that remains.
Surgical Procedure
A suction procedure, commonly called a D&C, removes the pregnancy tissue under anesthesia. It has the highest rate of complete evacuation and the shortest duration of bleeding. It’s typically done as an outpatient procedure, meaning you go home the same day. The infection rate is low across all three approaches, around 2 to 3%.
The choice between these options is genuinely personal. Some people prefer to let the process happen naturally. Others want the certainty and faster resolution of a procedure. None of these approaches affects your ability to get pregnant in the future.
Getting Pregnant Again After a Miscarriage
The odds of a healthy pregnancy after miscarriage are strongly in your favor. After one miscarriage, the risk of another is about 20%, which means four out of five subsequent pregnancies succeed. Even after two consecutive miscarriages, the risk only rises to about 25%. After three or more in a row, it reaches 30 to 40%, but even then, the majority of people go on to have healthy pregnancies.
Most people can try to conceive again after one normal menstrual cycle, though your provider may recommend additional testing if you’ve had two or more losses in a row. When a cause is identified, treating the underlying condition often improves outcomes. When no cause is found, the statistical outlook is still encouraging.