Miscarriage: What the NHS Says About Risk, and What Doesn't Cause It

Miscarriage is far more common than it's openly discussed, which leaves many people facing it feeling isolated, or worse, blaming themselves for something they didn't cause. This is an area where clear, NHS-sourced facts genuinely help — both to understand real risk factors, and to rule out the things guilt often points to that aren't actually responsible.

How common is miscarriage?

The NHS estimates that around 1 in 8 known pregnancies end in miscarriage, and the true rate is likely higher when very early pregnancy losses (before a person even knows they're pregnant) are included. The vast majority happen in the first trimester, before 12 weeks.

Genuine risk factors

• Age — risk increases with maternal age, more noticeably from the mid-30s and more significantly after 40, mainly linked to chromosomal factors in the egg.
• Previous miscarriage — having had one or more previous miscarriages modestly increases risk in subsequent pregnancies, though most people who've had one miscarriage go on to have a successful pregnancy.
• Certain health conditions — including poorly controlled diabetes, thyroid problems, and some blood clotting disorders.
• Smoking, heavy alcohol use, and drug use during pregnancy are all associated with increased risk.
• Being significantly overweight or underweight is also linked to modestly increased risk.

Most first-trimester miscarriages, though, are caused by random chromosomal abnormalities in the developing embryo — not by anything the parent did or didn't do, and not something that could have been prevented.

What does NOT cause miscarriage (despite common belief)

• Working during pregnancy, including standing or manual work, in the absence of a specific known risk
• Moderate exercise, including continuing an existing exercise routine
• Having sex
• Stress from everyday life (severe trauma is a different, separate consideration)
• Lifting moderate weights or reasonable physical activity
• Something you ate once, unless it involved a specific known risk (raw/undercooked meat, unpasteurised soft cheese, or similar)

This list matters because these are exactly the things people most often blame themselves for after a loss, when the evidence doesn't support any of them as a cause.

Signs to contact your GP or midwife about

Vaginal bleeding, with or without pain, is the most common sign and should always be assessed rather than waited out — most bleeding in early pregnancy does not lead to miscarriage, but it needs proper assessment either way, usually via an early pregnancy assessment unit.

Support after a miscarriage

The NHS and charities including Tommy's and the Miscarriage Association offer dedicated support, and many areas provide direct access to counselling after a loss — it's worth asking your GP or midwife directly what's available locally, rather than assuming you need to seek it out entirely on your own.