Hearing that a fetal heartbeat has been seen can bring a huge wave of relief, especially after early pregnancy anxiety or bleeding. It is also normal to still feel worried and to search for clear numbers.
This guide explains what “miscarriage risk after heartbeat” really means, how the chance of miscarriage after heartbeat changes over time, and which factors matter most.
What “heartbeat detected” means in early pregnancy
A heartbeat is usually confirmed on ultrasound, often by transvaginal scan in early weeks. “Heartbeat seen” is an important milestone because it confirms a viable intrauterine pregnancy at that moment.
But it is still a snapshot in time. Risk does not drop to zero instantly. Instead, miscarriage odds after heartbeat keep falling as pregnancy progresses, especially across weeks 7 to 10 and then into the end of the first trimester.
The typical chance of miscarriage after heartbeat
In people who have early pregnancy bleeding but an ongoing pregnancy with a confirmed heartbeat, patient information leaflets commonly quote a high likelihood of continuing the pregnancy. One NHS hospital leaflet states that after a heartbeat is seen, the chance of the pregnancy continuing is about 85 to 97 out of 100.
That range implies that the miscarriage risk after heartbeat is often roughly 3 percent to 15 percent in that threatened miscarriage context, depending on the individual situation and how far along the pregnancy is.
Important: those numbers are most applicable to people being evaluated for bleeding or pain in early pregnancy, not necessarily to every pregnancy in the general population.
Why the risk keeps dropping after heartbeat
The biggest driver of falling risk is gestational age. Early pregnancy losses are more common in the earliest weeks, and the probability of pregnancy continuing improves as development progresses.
If you are looking for a miscarriage calculator, the most important input is gestational age in weeks and days at the time the heartbeat was documented.
Factors that can change miscarriage probability after heartbeat
1. Vaginal bleeding or threatened miscarriage
Bleeding in early pregnancy is common, and many pregnancies continue normally. Still, bleeding can raise risk.
A classic clinical study looked at pregnancies after fetal heart activity was seen. It found higher loss rates in patients who had bleeding compared with those who did not.
So for a miscarriage risk after heartbeat, it is reasonable to include a yes or no input for bleeding, and optionally bleeding severity if you have reliable data.
2. Maternal age
Maternal age affects miscarriage risk overall, including after viability has been confirmed. In the same study, loss rates were higher among older patients compared with younger patients after fetal heart activity was documented.
3. Ultrasound findings beyond “heartbeat present”
A heartbeat being present is reassuring, but other ultrasound markers can matter, such as fetal size matching dates and heart rate being appropriate for gestational age. If you do not have high quality data for these, it is safer not to include them rather than guessing.
4. IVF or assisted reproduction pregnancies
Miscarriage rates and baseline risks can differ in IVF populations. A large IVF cohort study noted that pregnancy loss can still occur after cardiac activity is detected, with an overall loss rate of a few percent, even after fetal cardiac activity is seen.
Recommended disclaimers
Our calculator is educational, not diagnostic, and it may not apply to IVF, multiples, ectopic concerns, molar pregnancy, major medical conditions, or medication exposures. This is consistent with how early pregnancy services counsel patients and how clinical guidelines approach early pregnancy assessment.
When to contact a clinician urgently
- Even with a heartbeat confirmed, you should seek urgent medical care if there is
- Heavy bleeding, soaking pads
- Severe or worsening abdominal or pelvic pain
- Dizziness or fainting
- Fever or feeling very unwell
Early pregnancy services and miscarriage guidance emphasize assessment for pain and bleeding in early pregnancy because ectopic pregnancy and other complications must be ruled out.
