Miscarriage is most likely in the very early part of pregnancy, especially in the first trimester (up to about 12–13 weeks), with the highest risk in the first few weeks after conception.

When miscarriage is most likely

  • Around 10–20% of known pregnancies end in miscarriage, and about 80% of these losses happen in the first trimester.
  • The risk is highest in the earliest weeks (roughly weeks 3–6), when some losses may occur before a person even realizes they are pregnant and may look like a slightly late or heavy period.
  • After a heartbeat is seen on ultrasound (often around 6–7 weeks), the chance of miscarriage drops significantly, and the risk continues to decline as pregnancy progresses into the second trimester.

First trimester details

  • Many sources note that losses between weeks 3 and 4 can account for roughly one-quarter to one-third of very early pregnancies, especially those detected only with sensitive tests; these are often called chemical pregnancies.
  • From about weeks 5–6 onward, estimated miscarriage rates generally fall into the mid‑teens percentage range and keep decreasing with each passing week.

Second trimester and beyond

  • By the second trimester, miscarriage is much less common; estimates are often around 1–5% of recognized pregnancies for weeks roughly 13–19.
  • After about 20 weeks, pregnancy loss is usually termed a stillbirth rather than miscarriage, and this happens in well under 1% of pregnancies in many datasets.

Other factors that affect risk

  • Risk tends to rise with parental age, especially when the pregnant person is over 35 and more sharply after 40, and may also be influenced by older paternal age.
  • Health conditions (such as uncontrolled diabetes, certain autoimmune disorders, or uterine abnormalities), smoking, heavy alcohol use, and some infections can also increase the chance of miscarriage, while good preconception health and prenatal care are considered protective.

Gentle note

Miscarriage is common and usually not caused by anything a person did or did not do; most early losses are linked to chromosomal problems that happen by chance. If you are currently pregnant or have had a loss, it is important to talk with a healthcare professional for personalized risk estimates, reassurance, and support.

Information gathered from public forums or data available on the internet and portrayed here.