Shortness of Breath in Pregnancy

What normal breathlessness looks like

Tommy's states it simply: "It's normal to feel out of breath in pregnancy sometimes, especially as your baby grows bigger." The ordinary version has a recognisable shape — it starts gradually in early pregnancy or the second trimester, it builds as the pregnancy goes on, and it is provoked by doing things: stairs, hills, talking while walking uphill.

Crucially, Tommy's adds what it should not involve: "It should not be painful or come on suddenly and you shouldn't have other symptoms, such as wheezing or a cough."

That is the whole test, more or less. Gradual, exertional, painless and unaccompanied is the reassuring pattern. Sudden, severe, painful, or arriving with company is not.

Why this symptom gets missed

Because "I'm a bit out of breath" is such an ordinary sentence in pregnancy, it is easy for both you and a clinician to file it under normal. Tommy's makes the point directly: breathlessness can be a sign of anaemia, or of serious conditions called pulmonary embolism, pulmonary oedema and peripartum cardiomyopathy — conditions that can be overlooked precisely because their symptoms overlap with things pregnancy does anyway.

So the useful move is not to decide for yourself whether it is serious. It is to describe the pattern accurately, because the pattern is what tells them apart.

What is not normal

Tommy's lists the features that mean you should contact your doctor or midwife straight away:

• Shortness of breath that has only started, or has got a lot worse, in your third trimester.
• Shortness of breath that starts suddenly.
• Feeling out of breath when you are lying flat, and needing to sit or stand up to breathe properly — including needing to sleep sitting upright.
• Coughing or wheezing.
• Swelling in both legs or ankles alongside the breathlessness.
• Unusual tiredness that is affecting what you can do in a day.

The NHS applies the same logic in its list of pregnancy symptoms that need help: "if breathlessness comes on suddenly, you're out of breath when you're lying down, or you have other symptoms like chest pain or dizziness, this needs to be checked immediately."

When to call someone

Call your local emergency number (999 in the UK and Ireland, 911 in the US and Canada, 000 in Australia, or 111 in New Zealand) if you have breathlessness together with any of the things Tommy's lists as emergencies: fainting or dizziness, chest pain, coughing up blood, a racing or pounding heartbeat, swelling in one leg only, or a feeling that you are gasping or that your breathing is getting steadily worse.

The RCOG's wording on the same cluster is worth quoting, because it is what clinicians are trained to respond to. The symptoms of a blood clot on the lung are "sudden unexplained difficulty in breathing, tightness in the chest or chest pain, coughing up blood (haemoptysis), feeling very unwell or collapsing", and: "You should seek help immediately if you experience any of these symptoms."

Contact your maternity service immediately if one of your calves is red, swollen and hot — the HSE lists this among the signs that need immediate contact, because it can indicate a deep vein thrombosis.

Mention it at your next appointment, at minimum. Tommy's advice is that if you are feeling out of breath in pregnancy you should always mention it to your midwife or doctor next time you see them, even when it fits the normal pattern.

For perspective, not reassurance: the RCOG notes that venous thrombosis in pregnancy or in the six weeks after birth occurs "in only 1–2 in 1000 women". It is uncommon. It is also the reason the threshold for checking is deliberately low.

The one cause worth actively chasing

Anaemia is the most treatable thing on this list and the one most likely to be missed. The NHS lists "tiredness and lack of energy" and "shortness of breath" as the main symptoms of iron deficiency anaemia, along with heart palpitations, pale skin and headaches — and states that "heavy periods and pregnancy are very common causes of iron deficiency anaemia".

It is diagnosed with a full blood count, which you are likely having anyway as part of antenatal care, and treated with iron supplements taken for around six months. The NHS suggests taking them with orange juice to help absorption, and cutting back on tea, coffee and dairy around the same time because they reduce it.

If you are breathless and exhausted, "can we check my haemoglobin?" is a reasonable and cheap question.

What actually helps

Here is the honest answer: for ordinary pregnancy breathlessness, none of the guidance reviewed here offers a treatment. There is no recommended exercise, position or supplement that fixes it, because the cause is the pregnancy itself and it resolves when the pregnancy does. Sitting upright, slowing down and pacing yourself are sensible; they are not evidence-based interventions and nobody is pretending otherwise.

What the guidance does offer is advice on being heard — which tells you something about where the real risk sits. Tommy's suggests describing your symptoms clearly, explaining what they are stopping you doing, taking someone with you to appointments, and asking for a second opinion if you are not satisfied with the response.

Concretely, that means saying "this started suddenly two days ago", or "I can't lie flat any more", or "it's worse at rest than when I'm moving" — rather than "I've been a bit breathless." The first three sentences describe patterns that get investigated. The fourth describes pregnancy.

The short version

Gradual, exertional, painless breathlessness that builds through pregnancy is expected. Sudden breathlessness, breathlessness at rest or lying down, and breathlessness with chest pain, a cough, a racing heart or a swollen calf are not — and those need to be seen today, not mentioned in passing at your next appointment.