Making Sense of Miscarriage Statistics

What Conflicting Research Really Means

One common concern for many women, especially early in pregnancy, is the risk of miscarriage. If you're newly pregnant and trying to make sense of the myriad statistics about miscarriage, here's an explanation of each one that may ease your mind.

Miscarriage Rate for All Conceptions

If taking into account the number of known miscarriages and the number of unknown miscarriages, there is a greater chance of miscarriage than not. As alarming as this statement may be, it illustrates that pregnancy loss is a commonly occurring event. It usually goes entirely unnoticed, often because it occurred within days of the conception and the pregnancy was non-viable from the start.

Research involving in vitro fertilization (IVF) found that a very large percentage of harvested eggs harbored chromosome abnormalities, the leading cause of early-term miscarriage. Another study found that around 22% of all conceptions never even complete implantation. These anomalies help explain why so many miscarriages go unnoticed.

Based on the current evidence, if you factor in fertilized eggs that fail to implant along with pregnancies that end in miscarriage, around 70% to 75% of all conceptions will end in pregnancy loss.

This statistic is sobering. But it means that if you already know that you're pregnant, your odds of carrying your baby to term are good.

Miscarriage Rate After Implantation

Whether failed implantations can be defined as "miscarriage" is a matter of opinion. Most doctors consider pregnancy to begin at implantation rather than at fertilization. Within this context, the rate of miscarriage can differ considerably.

About 31% of pregnancies confirmed after implantation end in miscarriage. That translates to roughly one of every three pregnancies.

But before you worry too much about those figures, note that this number came from a study of a population of women who were confirmed to be pregnant at the very earliest point that it's scientifically possible to detect a pregnancy.

In real life, most women find out they are pregnant at a later point than the participants in this study, and the risk of miscarriage drops as pregnancy progresses. That would mean that most women have a lower risk of miscarriage by the time they confirm their pregnancies.

Many experts cite this statistic as an argument against taking ultra-sensitive early pregnancy tests before missing a menstrual period. Use of such tests increases the risk of detecting a nonviable pregnancy that will miscarry within a few days. Knowing about such pregnancies can be a source of stress for many women, and if this is true for you, it's worth waiting to test until your period is actually late.

Miscarriage After a Confirmed Pregnancy

For the general population of pregnant women, the miscarriage rate after a confirmed pregnancy is usually the most relevant statistic.

Research suggests that between 10% and 20% of women with a medically confirmed pregnancy will end in miscarriage. Eighty percent of these will occur during the first trimester.

The further along a pregnancy is, the lower the risk of miscarriage. Since many women who get pregnant do not track their periods, they may already be a few weeks along—possibly more than halfway through the first trimester—by the time the pregnancy is confirmed.

Since the majority of miscarriages occur within the first 12 weeks of gestation, the risk of pregnancy loss after 12 weeks drops dramatically, to between 3% and 4%. After 20 weeks, the risk is roughly 1 in 160 (or 0.6%).

Miscarriage After Fetal Heartbeat

Most doctors agree that seeing a fetal heartbeat on ultrasound means the risk of miscarriage is much lower. Confirmation of a fetal heartbeat means that the baby has passed the initial stages of development wherein the majority of first trimester miscarriages occur.

According to research from Monash University, the overall risk of miscarriage after the detection of a fetal heartbeat is around 4%, dropping to 1.5% after 8 weeks and 0.9% by 9 weeks.

The risk of miscarriage doesn't disappear at this time. But seeing the baby's heartbeat is a good sign. It means the baby is growing as it should be, and there's little reason to be concerned at this point.

Unfortunately, there is one exception to this rule: slow fetal heart rate (less than 100 beats per minute) may signal an impending miscarriage, especially as the pregnancy advances.

Recurrent Miscarriage Rate

Most first-time miscarriages are random and do not recur. With one past miscarriage, the odds of miscarrying in your next pregnancy are about 20%. This is not much higher than someone without a history of miscarriage.

With two previous miscarriages, the risk of another miscarriage is 28%, and with three previous miscarriages, the risk increases to 43%. It's possible that testing for recurrent miscarriage causes might help in these cases.

A Word From Verywell

As much as we hate to think so, miscarriage is of unavoidable. It is the body's way of stopping a pregnancy that has no chance of success. While there's not a whole lot you can do to affect your odds of a miscarriage, you may be able to lower your risk if you avoid alcohol, don't smoke, and minimize certain occupational hazards.

When you are pregnant or hope to become pregnant, you may be anxious to ensure you are doing everything right. It's easy to become overwhelmed by statistics. Try to focus on doing what is healthy for your body and nurturing your pregnancy.

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  2. Cohain JS, Buxbaum RE, Mankuta D. Spontaneous first trimester miscarriage rates per woman among parous women with 1 or more pregnancies of 24 weeks or more. BMC Pregnancy Childbirth. 2017;17(1):437. doi:10.1186/s12884-017-1620-1

  3. Tong S, Kaur A, Walker SP, Bryant V, Onwude JL, Permezel M. Miscarriage risk for asymptomatic women after a normal first-trimester prenatal visit. Obstet Gynecol. 2008;111(3):710-4. doi:10.1097/AOG.0b013e318163747c

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