What it is

Chelsea and Westminster Hospital NHS Foundation Trust defines it in one sentence: "A subchorionic haematoma (SCH) is bleeding or the build-up of blood between the wall of the uterus and the sac or membranes which protect the developing fetus, or later in pregnancy, underneath the placenta itself."

You may also see it written as subchorionic haemorrhage or subchorionic bleed. They are the same thing. The blood sits beside the pregnancy, not inside it.

On cause, the same leaflet is honest: "The cause is unclear. Partial separation of the membranes around the fetus away from the wall of the uterus is thought to be the cause." Nothing you did brought it on.

How you find out you have one

Usually through bleeding. Chelsea and Westminster note that vaginal bleeding is common in the first trimester and that SCH is the most common cause of it, and that the bleeding "can be anything from spotting to heavy bleeding with clots. There is not normally any pain, but some will experience mild cramping."

For context on how common early bleeding is in general, ACOG's patient information puts it at 15 to 25 in 100 pregnancies in the first trimester.

Sometimes there is no bleeding at all and the haematoma is picked up incidentally on a scan. And sometimes bleeding happens without a haematoma being visible — the Chelsea and Westminster leaflet notes that "occasionally the SCH cannot be seen on scan".

Any bleeding in early pregnancy should be assessed. The RCOG's route is your GP or midwife, your nearest early pregnancy assessment service, your local urgent care line, or the emergency department if bleeding is heavy or pain is severe.

What it means for the pregnancy — the honest version

Two things are true at once, and most articles pick only one of them.

The first: most of these pregnancies are fine. Chelsea and Westminster put it this way: "SCH, although not considered normal, is not an unusual finding and does not mean you will lose the pregnancy... Most pregnancies affected by a SCH progress normally, the SCH resolves on its own, and the pregnancy results in the delivery of a healthy baby with no additional complications."

The second: at population level the association with worse outcomes is real. A systematic review and meta-analysis by Tuuli and colleagues, published in Obstetrics & Gynecology in 2011, pooled seven studies covering 1,735 women with subchorionic haematoma and 70,703 controls. It found higher pooled odds of miscarriage (odds ratio 2.18, 95% CI 1.29 to 3.68, with the rate rising from 8.9% to 17.6%), placental abruption (OR 5.71, 95% CI 3.91 to 8.33, 0.7% to 3.6%), preterm birth (OR 1.40, 95% CI 1.18 to 1.68, 10.1% to 13.6%) and preterm prelabour rupture of membranes (OR 1.64, 95% CI 1.22 to 2.21, 2.3% to 3.8%). It found no significant association with pre-eclampsia or a small baby.

Read those absolute numbers, not just the ratios. A doubling of a small risk is still a small risk, and in that same analysis the great majority of pregnancies in both groups continued.

Chelsea and Westminster list the factors that make an individual haematoma more concerning: a larger haematoma, older maternal age, being diagnosed earlier in pregnancy, and — later on, once the placenta has formed — a bleed sitting behind the placenta rather than just behind the membranes. The leaflet also adds the caveat that matters: "Evidence for these complications is limited."

What is actually done about it

Mostly, monitoring. Chelsea and Westminster say that "no further follow up is required for most women with a viable intrauterine pregnancy", and that people who are still bleeding 14 days after the scan, or whose bleeding is getting worse, should contact the early pregnancy unit for another appointment. Heavy bleeding means the emergency department.

On progesterone, the position is narrower than the internet suggests. Chelsea and Westminster: "You may be offered progesterone pessaries to insert into the vagina, although the benefits of this for SCH have not been proven. However, if you have had a previous miscarriage and have any bleeding in early pregnancy, progesterone pessaries can help improve the outcome of the pregnancy and will be offered."

That second sentence tracks NICE's national recommendation, which is not about haematomas at all: NICE says to offer vaginal micronised progesterone 400 mg twice daily where there is an intrauterine pregnancy confirmed by scan, vaginal bleeding, and a previous miscarriage, continuing to 16 completed weeks if a heartbeat is confirmed. If you have not had a previous miscarriage, NICE's committee found no evidence of benefit.

On anti-D, NICE's 2026 update means the answer depends on how many weeks you are. NICE now says not to offer anti-D for miscarriage or threatened miscarriage up to and including 11+6 weeks, and to consider it at 12+0 to 12+6 weeks for threatened miscarriage with heavy or recurrent bleeding, at a dose of at least 250 IU (50 micrograms). Your blood group is checked at the early pregnancy unit partly for this reason.

Rest, exercise and sex

There is no evidence base for bed rest, and no national guideline recommends it. Chelsea and Westminster say so directly and then give a moderate practical line: "Generally speaking we recommend you go about your daily activities as normal, with only a few modifications. There is no evidence for bed rest, but we do recommend avoiding strenuous activities/ exercise or sexual intercourse."

That advice is a local judgement rather than a national recommendation, and the leaflet says the risk depends on the size of the haematoma. It is reasonable to ask your own team what they advise for your scan findings rather than adopting a stranger's rules.

When to stop waiting and call

Contact your early pregnancy service or emergency department immediately if you have:

heavy bleeding — soaking a period pad soon after putting it on
severe pain in your abdomen
pain in your shoulder
dizziness or fainting

The RCOG lists those together because they are the signs of an ectopic pregnancy, which a haematoma diagnosis does not rule out if the pregnancy has not been clearly located inside the uterus. The NHS gives the same emergency threshold for bleeding in pregnancy generally.

Later on, any fresh bleeding after the first trimester should be reported the same day. ACOG is explicit that bleeding later in pregnancy can be more serious and should prompt contact with your team or a hospital visit.

What nobody can tell you

There is no validated way to convert the size of your haematoma into a personal probability, and anyone offering you one online is inventing it. Serial scans exist because the picture changes: many haematomas shrink and disappear over a few weeks, and the bleeding often becomes brown before it stops, which is old blood leaving rather than a new problem starting.

What you can reasonably ask at your next appointment: where exactly the bleed is sitting, whether the pregnancy has been confirmed inside the uterus, whether you need anti-D at your gestation, whether progesterone applies to you under the NICE criteria, and when they want to scan you again.

Subchorionic Haematoma