About 10 to 25 percent of all clinically recognized pregnancies end in miscarriage. The wide range reflects differences in how early a pregnancy is detected and the age of the person carrying it. When counting only confirmed pregnancies (those with a positive test and a visit to a healthcare provider), the figure narrows to roughly 10 percent. The true number, including losses that happen before a person even knows they’re pregnant, is almost certainly higher.
Why the Range Is So Wide
The gap between 10 and 25 percent comes down to timing. Many pregnancies end in the first few days after implantation, sometimes showing up only as a late or heavy period. These very early losses, sometimes called chemical pregnancies, are often never recorded. Once a pregnancy is clinically recognized, meaning confirmed by a provider with an ultrasound or blood work, the rate settles closer to 10 percent. About 80 percent of all miscarriages occur within the first trimester, before 13 weeks of gestation.
How Risk Changes Week by Week
The risk of miscarriage drops significantly as a pregnancy progresses. Once a heartbeat is confirmed around six weeks, the chance of loss falls to about 10 percent. By week 12, it drops to roughly 5 percent. In the second trimester (weeks 13 through 20), the rate falls further to between 1 and 5 percent. Each passing week with a healthy heartbeat substantially improves the odds of carrying to term.
This steep decline is why many people choose to wait until the end of the first trimester to share pregnancy news. It’s also why the anxiety of early pregnancy is so common, and so normal.
Maternal Age and Miscarriage Risk
Age is the single largest factor affecting miscarriage rates. The numbers shift dramatically after 35:
- Ages 20 to 30: 9 to 17 percent
- Age 35: about 20 percent (1 in 5)
- Age 40: about 40 percent (4 in 10)
- Age 45: about 80 percent (8 in 10)
The jump between 35 and 40 is particularly sharp. This increase is driven largely by egg quality. As eggs age, they’re more likely to have chromosomal errors during cell division, and those errors are the leading cause of early pregnancy loss.
What Causes Most Miscarriages
Roughly 50 percent of first-trimester miscarriages result from chromosomal abnormalities in the embryo. These are random errors that occur when the egg and sperm combine or when cells first begin dividing. The embryo receives too many or too few chromosomes, making normal development impossible. This type of loss is not caused by anything the pregnant person did or didn’t do.
Other factors that can contribute include hormonal imbalances (particularly progesterone levels too low to sustain the uterine lining), structural issues with the uterus, certain infections, and chronic health conditions like uncontrolled diabetes or thyroid disorders. In many cases, though, no specific cause is ever identified. That uncertainty can be one of the hardest parts of the experience.
Risk After a Previous Miscarriage
Having one miscarriage does not mean you’re likely to have another, though the odds do increase incrementally with each consecutive loss. After one miscarriage, the risk of another is about 20 percent. After two consecutive losses, it rises to roughly 25 percent. After three or more in a row, the risk climbs to 30 to 40 percent.
Even after three losses, the majority of people still go on to have a successful pregnancy. Providers typically begin investigating potential underlying causes after two or three consecutive miscarriages, looking at factors like blood clotting disorders, uterine shape, hormonal levels, and chromosomal patterns in both partners. This evaluation can sometimes identify a treatable cause that improves the chances of carrying a future pregnancy to term.
What Counts as a Miscarriage
Medically, miscarriage refers to the loss of a pregnancy before 20 weeks of gestation. The American College of Obstetricians and Gynecologists uses the term “early pregnancy loss” for losses in the first trimester (before about 13 weeks). A loss after 20 weeks is classified as a stillbirth, which is a separate and much rarer event.
The terminology can feel clinical and cold, especially in the moment. Some people experience a miscarriage as a brief episode of heavy bleeding, while others require medical intervention to complete the process. The physical experience varies widely depending on how far along the pregnancy was and individual circumstances. Emotionally, the impact can be significant regardless of how early the loss occurred.