Nearly two-thirds of missed miscarriages are caused by chromosomal abnormalities in the embryo, meaning the pregnancy ended because of a random genetic error during fertilization or early cell division. A missed miscarriage (also called a silent miscarriage) is one where the embryo stops developing but your body doesn’t expel the pregnancy tissue right away. You may still feel pregnant, test positive, and have no bleeding or cramping, which is why the loss often comes as a shock at a routine ultrasound.
Chromosomal Errors Are the Leading Cause
In a large genetic analysis published in Frontiers in Genetics, roughly 64.8% of missed miscarriage embryos had chromosomal abnormalities, compared to just 3.9% in pregnancies that ended through other types of miscarriage. These aren’t inherited conditions. They’re random errors that happen when the egg or sperm forms, or during the earliest cell divisions after fertilization. The embryo ends up with too many or too few chromosomes, and at some point it simply cannot continue developing.
The most common specific errors found were monosomy X (a missing sex chromosome) and trisomy 16 (an extra copy of chromosome 16), each accounting for about 23% of the abnormal cases. Trisomy 22, trisomy 2, and trisomy 15 rounded out the top five. None of these reflect anything you did or didn’t do during pregnancy. They reflect the biology of human reproduction, which is surprisingly error-prone at the cellular level.
Why Your Body Didn’t Recognize the Loss
In a typical miscarriage, the body detects that the pregnancy is no longer viable, hormone levels drop, and cramping and bleeding follow. In a missed miscarriage, that recognition is delayed. The placental tissue can continue producing pregnancy hormones even after the embryo has stopped growing, which keeps your body in “pregnant mode.” Your hCG levels may plateau or rise very slowly rather than dropping sharply, so nausea, breast tenderness, and other early symptoms can persist for days or even weeks after the embryo has stopped developing.
It’s not fully understood why some miscarriages trigger immediate physical symptoms while others stay silent. The Miscarriage Association notes that this delay can vary widely from person to person, and there’s no clear explanation for why pregnancy hormone levels remain elevated longer in some cases. This is not a failure of your body. It’s an unpredictable variation in how the hormonal signaling system responds to loss.
Other Factors That Can Play a Role
While chromosomal problems account for the majority of cases, a smaller number of missed miscarriages are linked to maternal health conditions. Uncontrolled diabetes, thyroid disease, hormonal imbalances, infections, and obesity can all raise the risk. These are factors worth discussing with your doctor, especially if you experience more than one loss, because many of them can be managed before a future pregnancy.
Structural differences in the uterus can also contribute. A uterine septum, which is a band of tissue dividing part of the uterine cavity, is associated with significantly higher rates of first-trimester loss. In one study, 42% of pregnancies in people with a septate uterus ended in first-trimester miscarriage, compared to 12% in those without any uterine anomaly. Larger septums tend to cause more problems than smaller ones. If you’ve had recurrent losses, imaging of the uterus can help identify or rule out this kind of issue.
How a Missed Miscarriage Is Diagnosed
Diagnosis relies on ultrasound measurements, and doctors follow conservative thresholds to avoid any chance of misdiagnosis. A pregnancy is generally considered nonviable when an embryo measures 7 mm or more in length with no detectable heartbeat, or when a gestational sac reaches 25 mm in diameter with no visible embryo inside. If measurements fall below those cutoffs, you’ll typically be asked to return for a follow-up scan in one to two weeks to confirm the diagnosis before any decisions are made.
Blood draws tracking your hCG levels can provide supporting information. In a healthy early pregnancy, hCG roughly doubles every 48 to 72 hours. Levels that rise very slowly (say, from 120 to 130 over two days) or that decline from one draw to the next suggest the pregnancy is no longer developing. But hCG alone isn’t used to make the final call. Ultrasound is the definitive tool.
What Happens Next
Once a missed miscarriage is confirmed, you generally have three options for how to proceed. Expectant management means waiting for the miscarriage to happen on its own. Given enough time (up to eight weeks), this approach results in complete expulsion of pregnancy tissue in about 80% of cases. Some people prefer this because it avoids medication and procedures, but the unpredictable timing can be emotionally difficult.
Medical management uses medication to prompt the uterus to expel the tissue. In the largest U.S. trial, about 71% of women had complete expulsion within three days of the first dose. A second dose, if needed, raised the success rate to 84%. This option gives more control over timing while still avoiding a procedure.
Surgical management, typically a procedure called a D&C, removes the tissue directly. It’s the quickest option and is sometimes recommended when the other approaches haven’t worked or if there are signs of infection. The procedure itself is short and usually done under sedation.
All three approaches are considered safe and effective. The choice comes down to your personal preference, how far along the pregnancy was, and your doctor’s guidance based on your specific situation.
Physical Recovery Timeline
After the pregnancy tissue passes or is removed, pregnancy symptoms like nausea typically fade within a few days. Spotting or light bleeding can continue for a couple of weeks. Most people get their first period about two weeks after the bleeding stops, which works out to roughly two to three months after the miscarriage resolves. That first period signals that your cycle is resetting.
Your Chances in a Future Pregnancy
A single miscarriage, including a missed miscarriage, does not substantially change your odds of carrying a future pregnancy to term. After one loss, the risk of miscarriage in a subsequent pregnancy is about 20%, which is only slightly higher than the baseline risk for any pregnancy. After two consecutive losses, that risk rises to about 25%. Even after three or more losses in a row, the majority of people (60% to 70%) go on to have a successful pregnancy.
If this was your first miscarriage, there’s typically no need for specialized testing. If you’ve had two or more, your doctor may recommend blood work to check for clotting disorders, hormonal issues, or thyroid problems, along with imaging to evaluate the shape of your uterus. These tests can sometimes identify a treatable cause, but in many cases, no specific explanation is found, and the next pregnancy still proceeds normally.