Miscarriage is the most common complication of pregnancy and one of the least spoken about. One in five confirmed pregnancies ends in miscarriage; the true rate, including pregnancies lost before they are detected, is considerably higher. Despite this frequency, people who miscarry often find themselves navigating a loss that is barely acknowledged by the world around them, frequently alone, and frequently with unspoken questions about what they did wrong.
The answer to that question is almost always: nothing. The biology of early pregnancy loss is better understood now than it was twenty years ago, and the evidence is clear that the overwhelming majority of early miscarriages are caused by chromosomal abnormalities in the embryo. They are not caused by exercise, stress, food, sex, or any other common behaviour of daily life.
Healthbooq (healthbooq.com/apps/healthbooq-kids) covers pregnancy and reproductive health.
How Common Miscarriage Is
Around 15-20% of confirmed pregnancies end in miscarriage. Most losses occur in the first trimester (before 12 weeks), with the risk falling sharply after a heartbeat is detected at 6-7 weeks. The NHS estimates approximately 250,000 miscarriages occur in the UK each year.
Risk increases with maternal age: at 25-29, miscarriage risk is approximately 13%; at 35-39, approximately 20%; at 40-44, approximately 40%. This age-related increase is primarily driven by the rising rate of chromosomal aneuploidy in eggs with advancing age.
Why Miscarriage Happens
In the first trimester, the cause in approximately 60-70% of cases is a chromosomal abnormality in the embryo, most commonly trisomy (three copies of a chromosome instead of two). This is not inherited and does not indicate anything wrong with either parent's chromosomes: it arises as a random error during cell division in the very early embryo or egg. The body recognises that development cannot proceed and the pregnancy fails.
Other causes include structural abnormalities of the uterus, antiphospholipid syndrome (in which antibodies interfere with placentation), uncontrolled thyroid disease, and, rarely, infections. For most individual first-trimester miscarriages, investigation is not performed or recommended.
Types of Miscarriage
An early pregnancy assessment unit (EPAU) will often classify a miscarriage using specific terms. A threatened miscarriage is bleeding in early pregnancy with a viable embryo on ultrasound; many threatened miscarriages do not progress to loss. An inevitable miscarriage involves bleeding and dilation of the cervix. An incomplete miscarriage means some, but not all, pregnancy tissue has passed. A missed (or silent) miscarriage is when the embryo has died but no bleeding has occurred: it is often discovered at a routine scan.
A blighted ovum (anembryonic pregnancy) is a gestational sac with no visible embryo, caused by very early embryonic failure.
Management Options
When a miscarriage is diagnosed, there are three management options, each appropriate in different circumstances.
Expectant management means waiting for the miscarriage to complete naturally. Bleeding and cramping can be significant, lasting from a few days to several weeks. This is appropriate for women who are medically stable and prefer to avoid intervention; success rates for complete resolution within 2-4 weeks are around 50-80% for incomplete miscarriages.
Medical management uses misoprostol, a prostaglandin that causes uterine contractions and expulsion of pregnancy tissue. It can be used vaginally or sublingually and is effective in around 80% of cases. It causes cramping, often significant, usually within hours of administration.
Surgical management – evacuation of retained products of conception (ERPC), now often performed under local anaesthesia as an outpatient procedure – removes the pregnancy tissue surgically. It is recommended when there are signs of infection, heavy bleeding, or when expectant and medical management have not been successful. The procedure takes approximately 10-20 minutes. Recovery is rapid for most women.
No option is clinically superior for uncomplicated miscarriage; the choice is personal and guided by the individual's circumstances and preferences.
The Emotional Impact
The emotional impact of miscarriage is not proportional to gestational age, and it is not predictable. Some people experience profound grief; others feel primarily relief or practical concern. Both responses, and everything between them, are normal. Grief for a miscarriage is real grief, regardless of how early the loss occurred. Partners frequently grieve too, often without the same social permission to acknowledge it.
Research by the Tommy's pregnancy charity and by Siobhan Quenby at the University of Warwick has highlighted the inadequate emotional support many people receive after miscarriage. The Miscarriage Association runs a helpline and provides peer support. Partners should also be offered support.
A common experience is isolation: the pregnancy was often not yet known to most friends and family, so the loss cannot be spoken about without first revealing the pregnancy. This invisibility compounds the grief.
Recurrent Miscarriage
Recurrent miscarriage is defined as three or more consecutive pregnancy losses, and affects approximately 1% of couples. Causes include chromosomal abnormalities in one or both parents; antiphospholipid syndrome (treatable with aspirin and heparin); uterine abnormalities (such as a uterine septum); and thrombophilias. In approximately 50% of recurrent miscarriage cases, no cause is found despite investigation.
Investigation and management is provided through specialist recurrent miscarriage clinics. Tommy's National Centre for Miscarriage Research (led by Siobhan Quenby) is the UK's leading research programme in this area. Women with unexplained recurrent miscarriage who are seen in a dedicated clinic have better outcomes, possibly due to closer surveillance and support.
Future Pregnancy
After one miscarriage, the chance of a successful next pregnancy is around 85%. After two miscarriages, approximately 75%. After three, approximately 65%. These figures are reassuring, though they do not always feel that way in the immediate aftermath of loss.
There is no standard evidence-based recommendation to wait a specific time before trying to conceive again after a miscarriage; most guidance suggests waiting until any bleeding has stopped and the person feels emotionally ready. A recent large study (Bhattacharya et al., BMJ 2010) found that conception within 6 months of miscarriage was associated with better outcomes than longer waits.
Key Takeaways
Miscarriage – the loss of a pregnancy before 24 weeks – affects approximately 1 in 5 confirmed pregnancies in the UK, making it by far the most common complication of pregnancy. The majority of miscarriages occur in the first trimester and are caused by chromosomal abnormalities in the embryo rather than anything the pregnant person did. Management options include expectant management (waiting for the miscarriage to complete naturally), medical management with misoprostol, or surgical management (ERPC). Emotional recovery varies enormously and does not follow a predictable timeline. Around 1% of couples experience recurrent miscarriage (three or more losses), which warrants specialist investigation.
