Miscarriage risk by week falls steeply as early pregnancy progresses: the chance of miscarriage from week 4 onward is about 20%, but by week 8 the remaining risk has dropped to roughly 2.5%, and by week 12 it is under 1% (0.9%). In other words, every week — in fact, every single day — that passes makes a continuing pregnancy more likely, and the table below shows exactly how the odds improve from week 4 to week 20. Updated 2026.
One definition matters before you read the numbers. "Miscarriage risk by week" in this article means the remaining risk: if you have reached a particular week still pregnant, it is the probability that the pregnancy will still end in miscarriage from that week onward. It is not the chance of miscarrying during that one week alone. Each figure is shown alongside its flip side — the chance of the pregnancy continuing — because for most people that is the more reassuring way to read it. If you would like the number for your exact week right away, our miscarriage risk calculator works it out from your dates.
Miscarriage Risk by Week: The Full Table, Weeks 4 to 20
The remaining risk of miscarriage drops from 20.0% at week 4 to 0.3% at week 20, and it crosses below 1% at week 12. These are modeled baseline estimates for an average pregnancy; personal odds also shift with age and with whether a heartbeat has been seen, and both of those factors are covered further down.
| Week of pregnancy | Chance of miscarriage from this week onward | Chance of pregnancy continuing |
|---|---|---|
| 4 | 20.0% | 80.0% |
| 5 | 14.0% | 86.0% |
| 6 | 9.4% | 90.6% |
| 7 | 4.2% | 95.8% |
| 8 | 2.5% | 97.5% |
| 9 | 1.9% | 98.1% |
| 10 | 1.5% | 98.5% |
| 11 | 1.1% | 98.9% |
| 12 | 0.9% | 99.1% |
| 13 | 0.8% | 99.2% |
| 14 | 0.7% | 99.3% |
| 15 | 0.6% | 99.4% |
| 16 | 0.5% | 99.5% |
| 17 | 0.45% | 99.55% |
| 18 | 0.4% | 99.6% |
| 19 | 0.35% | 99.65% |
| 20 | 0.3% | 99.7% |
How to Read This Table: A Worked Example
Take week 7 as an example: a remaining miscarriage risk of 4.2% means that out of 1,000 pregnancies that have reached week 7, about 42 would still be expected to end in miscarriage — and about 958 would continue. The same logic applies at every row: subtract the miscarriage figure from 100 and you get the continuation chance. If you are unsure which week you are in, the how many weeks pregnant am I calculator works it out from your last period, and our pregnancy week by week guide shows what is developing at each stage.
Why Miscarriage Risk Falls So Quickly in the First Trimester
Miscarriage risk falls quickly because the great majority of losses happen very early: about 80% of all miscarriages occur in the first trimester, and overall roughly 10–15% of recognized pregnancies end in miscarriage (ACOG). Most early losses are caused by chromosomal abnormalities — random errors at conception that mean the pregnancy could never have developed — and those pregnancies tend to end in the first few weeks, often before an ultrasound is even booked.
Each Week Passed Is a Test Passed
Because the highest-risk pregnancies end earliest, simply reaching a new week is meaningful evidence in your favor. A pregnancy that has reached week 8 has already passed through the window in which most chromosomal losses occur, which is why its remaining risk (2.5%) is so much lower than the week 4 figure (20.0%). The curve is steepest between weeks 6 and 10, when the remaining risk falls from 9.4% to 1.5% — a drop of nearly 8 percentage points in about a month.
Miscarriage Risk After a Fetal Heartbeat Is Seen
Seeing a fetal heartbeat on ultrasound lowers the risk further: in a widely cited study, the risk of miscarriage after a heartbeat was confirmed was 9.4% at 6 weeks, 4.2% at 7 weeks, 1.5% at 8 weeks, 0.5% at 9 weeks, and 0.7% at 10 weeks (Tong et al., Obstetrics & Gynecology, 2008). A heartbeat usually becomes visible on a transvaginal ultrasound at around 6 to 7 weeks, which is why an early scan can be so reassuring.
What the Heartbeat Numbers Mean in Practice
At 8 weeks with a heartbeat seen, the Tong et al. figures imply roughly a 98.5% chance of the pregnancy continuing — noticeably better than the 97.5% baseline for week 8 in the main table, which blends pregnancies with and without a confirmed heartbeat. If you have just had an early scan, our detailed guide to miscarriage odds after heartbeat walks through these figures week by week, including how they change with maternal age.
Every Day Counts: How Fast the Risk Drops Day by Day
The risk does not fall in weekly steps — it falls every day. Between 6 weeks 0 days and 7 weeks 0 days, the remaining risk drops from 9.4% to 4.2%, a fall of 5.2 percentage points over 7 days, or roughly 0.7 percentage points per day. That daily pace is the fastest reassurance gain of the whole pregnancy; between weeks 6 and 10 each passing day is worth, on average, about half a percentage point to a full percentage point of reduced risk.
This is worth remembering if you are counting down the days to a first scan or to the 12-week milestone. You do not have to reach week 12 to be in a much safer position than you were at week 5: by week 8, about two-thirds of the total first-trimester risk drop has already happened. Anxiety in these weeks is completely normal, and watching the numbers move in your favor, even slowly, helps many people get through them.
What These Baseline Numbers Do Not Capture
Baseline tables describe an average pregnancy, and your personal risk can sit above or below them. The strongest single modifier is maternal age: risk rises gradually through the thirties and more steeply after 40, which we break down in our guide to miscarriage risk by age. Other factors include a history of previous miscarriages, certain chronic conditions such as uncontrolled diabetes or thyroid disease, smoking, and how the pregnancy was conceived.
Risk After IVF and in the Second Trimester
Pregnancies conceived with fertility treatment follow the same falling curve once a heartbeat is confirmed, though the earliest weeks carry some extra uncertainty; our article on miscarriage after IVF covers conception-specific odds in detail. After week 13, the risk becomes small for everyone: loss in the second trimester affects roughly 1–5% of pregnancies overall, and by week 20 the remaining risk in the table above has fallen to just 0.3%. Statistics, however reassuring, describe groups rather than individuals — they cannot predict or diagnose your own pregnancy, and symptoms always matter more than averages.
When to Contact Your Doctor or Midwife
Contact your doctor, midwife, or local early pregnancy unit promptly if you have heavy vaginal bleeding (soaking a pad in an hour), severe one-sided pelvic pain, pain in the tip of your shoulder, fever, or dizziness or fainting. Light spotting and mild cramping are common in healthy early pregnancies and very often turn out to be nothing — but they are always worth a phone call, both for your safety and for your peace of mind.
If the waiting is the hardest part, it can help to look at your own numbers rather than the general ones. Take a moment to check your own week-by-week odds — for most people in early pregnancy, the figure for their current week is far more reassuring than they feared, and it improves with every day that passes.