Miscarriage
Miscarriage is common, and it is rarely caused by anything you did or didn't do. This page covers why miscarriage happens, the main options for managing one, and an estimate tool for the chance of miscarriage from your current stage of pregnancy. If you are going through this now, please reach out to the rooms — you don't need to navigate it alone.
How common is miscarriage?
Miscarriage — the loss of a pregnancy before 20 weeks — is one of the most common complications of early pregnancy, affecting roughly 1 in 6 to 1 in 5 clinically recognised pregnancies overall. The real figure is higher again if very early losses that happen before a pregnancy test would turn positive are included. About three-quarters of all miscarriages happen in the first trimester, and the risk of loss falls sharply once an ultrasound has confirmed a normal, ongoing pregnancy with a visible heartbeat.
Because it is so common and so rarely talked about, miscarriage can feel isolating. It is almost never the result of exercise, work, stress, sex, or something eaten or not eaten — the great majority trace back to a one-off genetic problem in that particular pregnancy, not a problem with either parent's health.
What causes a miscarriage?
Most single, early miscarriages have an identifiable biological cause, even when nothing could have been done to prevent it. The most frequent contributors are:
Chromosomal abnormalities (the most common cause)
Roughly half of first-trimester miscarriages occur because the embryo has the wrong number of chromosomes — most often an extra or missing chromosome (a trisomy or monosomy) arising randomly at conception. These errors become more frequent with increasing maternal (and to a lesser extent paternal) age, which is the main reason miscarriage risk rises with age. They are almost always a one-off event rather than an inherited condition.
Anatomical factors
Variations in the shape of the uterus (such as a septate uterus), fibroids that distort the uterine cavity, scar tissue (Asherman's syndrome), or a cervix that opens too early (cervical insufficiency) can contribute, particularly to later first-trimester or second-trimester losses.
Hormonal & metabolic factors
Poorly controlled thyroid disease, poorly controlled diabetes, and polycystic ovary syndrome are all associated with a modestly increased risk, as these conditions can be optimised before a future pregnancy.
Immune & clotting disorders
Antiphospholipid syndrome and certain inherited clotting (thrombophilia) conditions are linked to recurrent miscarriage and are part of the work-up after several losses.
Infections & lifestyle factors
Certain infections, smoking, heavy alcohol use, and obesity are each associated with a somewhat higher background risk, and are areas where changes can meaningfully help going forward.
Unexplained
In a proportion of miscarriages, particularly a first, isolated loss, no clear cause is ever found even after full assessment — this does not mean a cause wasn't a chromosomal one, only that it can't be tested for after the fact.
A single miscarriage does not usually need investigation. After two or three consecutive losses, Dr McCaffrey will typically arrange a set of tests looking at some of the factors above.
Management options
Once a miscarriage is confirmed, there are three main ways it can be managed. All three are safe, evidence-based options — the right choice depends on how the miscarriage is presenting, your preferences, and how you're doing. Dr McCaffrey will talk through which options are suitable for your situation.
| Option | What it involves | Typical success rate* |
|---|---|---|
| Conservative (expectant) | Waiting for the pregnancy tissue to pass naturally, with no medication or procedure, monitored with follow-up scans and/or blood tests. | ~70% complete by 2 weeks, ~81% by 6 weeks (varies by type of miscarriage) |
| Medical | Misoprostol tablets (taken orally or vaginally), sometimes combined with mifepristone beforehand, to help the uterus pass the tissue over a few days. | ~81–95% complete, depending on miscarriage type and regimen |
| Surgical | A short day-procedure (suction curette, sometimes called an ERPC or D&C) under sedation or general anaesthetic to remove the pregnancy tissue directly. | ~97–98% complete in a single procedure |
Conservative management avoids any procedure or medication, but takes longer and has a small chance of heavier bleeding or infection (roughly 1–3%) — it suits women who are stable, not bleeding heavily, and who would prefer to let things happen naturally with close follow-up.
Medical management shortens the process considerably and can usually be managed at home, but involves cramping, bleeding, and sometimes gastrointestinal side effects from the medication; around 1 in 10–20 women who choose this option will still need a surgical procedure if it doesn't fully work.
Surgical management is the most predictable and fastest option, and is generally recommended if there is heavy bleeding, signs of infection, or if the other two approaches haven't worked. It carries the usual small risks of any day procedure (bleeding, infection, rarely uterine injury or scarring) but has the highest single-attempt success rate.
There is no evidence that any one option affects future fertility differently from the others when performed appropriately — the choice comes down to safety, timing, and personal preference.
After a miscarriage
Physically, most women recover within one to two weeks, though a period-like bleed can continue intermittently for up to three or four weeks. It is safe to try to conceive again after one normal menstrual cycle, and there is good evidence that trying again sooner, once you feel ready, is not associated with a worse outcome. Emotionally, miscarriage can be just as significant as any other loss, whatever the gestation — it is entirely normal to need time, and support is available through the rooms, your GP, or dedicated pregnancy loss counselling services if that would help.