Breathless during pregnancy? What's normal, and the signs that need a doctor now

Feeling breathless during pregnancy is common and usually harmless. KK Women's and Children's Hospital (KKH) explains that your body needs more oxygen as the baby grows, and from the third trimester your womb presses up on your diaphragm and leaves your lungs less room. Dizziness is common in the first 20 weeks, when your blood pressure dips, and tiredness hits hardest in the first 12. What isn't normal is breathlessness that comes on suddenly with chest pain or a fever, or breathlessness that keeps going alongside palpitations or dizziness. KKH says to get help immediately for the first and to see a doctor for the second, because a blood clot in the lungs or a chest infection has to be ruled out.

Quick check: normal, see a doctor, or go now

This table pulls together what KKH, SingHealth and HealthHub list for the three symptoms pregnant women ask about most. Anything in the right-hand column needs a doctor that same day; call 995 if it is an emergency.

Sources for each row: KKH's guides to common pregnancy symptoms and coping with them, KKH's week 27 note on breathlessness, SingHealth's pregnancy do's and don'ts, and HealthHub's list of pregnancy warning signs from Singapore General Hospital.

Why you feel breathless, trimester by trimester

In the second trimester the cause is mostly demand. KKH's week 27 note says breathlessness is a very common complaint, and at that stage it comes from your body's rising need for oxygen. By week 28, KKH says, your baby is about three quarters of the way up your tummy.

In the third trimester the cause becomes space. The enlarging womb weighs on your diaphragm, the flat muscle under your lungs that does most of the work of breathing, so each breath has less room. KKH notes you may feel breathless more often as you move through the last trimester. Stairs, a fast walk to catch a bus, or lying flat on your back are the usual triggers.

Our week guides, such as 27 weeks pregnant, follow these changes as they come.

What helps when you're short of breath

• Change position. KKH suggests sitting upright, sleeping propped up on pillows, or lying on your side, all of which give your chest more room to expand.
• Breathe slowly. KKH's advice is slow, relaxed, deep breaths in and out.
• Slow down on stairs and pause on the landing.
• Take breaks in air-conditioning on hot days, and drink enough fluids.
• Keep exercising, but gently. SingHealth's list of warning signs during exercise includes shortness of breath, dizziness or feeling faint, chest pain and excessive fatigue; stop and see your doctor if any of them appear.

Lying on your back gets harder as the bump grows. KKH advises not to lie flat on your back after about mid-pregnancy, which also helps with dizziness. Our guide to pregnancy sleeping positions has pillow setups that keep you on your side, and safe exercise during pregnancy covers how hard to push.

Dizziness and feeling faint

KKH explains that your blood pressure falls in the first 20 weeks, so standing for a long time or getting up quickly from sitting or lying down can make you giddy. KKH's coping guide adds a few other moments: getting off the toilet, climbing out of a bath, or lying on your back later in pregnancy.

• Get up slowly. Sit on the edge of the bed for a moment before you stand.
• Lie on one side with your belly supported on a small pillow, and avoid lying flat on your back after mid-pregnancy (KKH).
• Drink enough fluids and exercise somewhere cool. KKH links poor food and fluid intake from morning sickness to dehydration, which makes dizziness worse.
• Eat regular meals to keep your energy steady, as KKH's pregnancy programme suggests.
• If you feel faint, sit or lie down on your side straight away, wherever you are.

Singapore's heat adds to it. A crowded MRT platform or a long queue outdoors is a common place to feel woozy, so carry water and sit when you can. Our guide to pregnancy in the Singapore heat has more ways to stay cool. If morning sickness means you can't keep fluids down, see morning sickness remedies and call your doctor early.

Dizziness is a warning sign when it travels with other symptoms. HealthHub, using SGH's pregnancy booklet, says a severe headache or swelling with dizziness, vomiting, blurred vision or upper abdominal pain could be pre-eclampsia, which is dangerous if left unchecked. Dizziness with heavy bleeding or severe tummy pain in early pregnancy needs urgent care too.

Tiredness, and when it could be anaemia

KKH says it's common to feel tired in pregnancy, especially in the first 12 weeks, when hormone changes can leave you feeling sick, emotional and run down. Later, broken sleep and the extra weight you carry take over. KKH's advice is to nap and rest when you can, accept offers of help, and keep up regular moderate activity such as walking.

Anaemia is the condition to rule out when tiredness and breathlessness come together. SingHealth's anaemia guide says iron deficiency is the most common cause in pregnancy, and KKH explains why: your blood volume rises and your baby needs iron too. You'll have a full blood count early in pregnancy, at around 10 to 12 weeks, and again at 24 to 28 weeks. If you're anaemic, you'll be started on iron tablets, usually 60 to 100mg of elemental iron a day, with a repeat blood test four weeks later.

• Take iron tablets before food on an empty stomach for better absorption, unless your doctor gives you a type meant to be taken with food.
• Keep coffee, black tea, milk and other calcium-rich foods two hours away from your iron.
• Pair iron-rich foods such as red meat, poultry, fish, tofu, beans and dark leafy greens with vitamin C from fruit; our guide to iron-rich foods for pregnancy has hawker swaps.
• Dark stools are normal on iron tablets, KKH notes.

Tiredness that comes with low mood most days for up to two weeks is worth raising as well. SingHealth's pregnancy guidance asks you to tell your doctor if you have symptoms of depression or anxiety for that long. Our guide to coffee while pregnant explains how to time caffeine around iron, and eating well in pregnancy lists iron-rich local dishes.

Where to go in Singapore

For a true emergency, such as sudden breathlessness with chest pain, fainting or heavy bleeding, call 995 for an ambulance. For urgent pregnancy problems that aren't life-threatening, KKH's Urgent O&G Centre at Basement 1 of the Women's Tower is a 24-hour walk-in centre for acute problems before 22 weeks, such as bleeding or tummy pain. From 22 weeks, KKH asks women with concerns such as bleeding, leaking fluid or signs of labour to go straight to its Delivery Suite on Level 2 of the Women's Tower instead. If you're booked at another hospital, call its delivery suite or labour ward, and bring your antenatal records.

For symptoms that don't need same-day care, book an earlier review with your gynae or polyclinic rather than waiting for the next scheduled visit. Our guide to common pregnancy discomforts by trimester covers the rest of the list, from heartburn to leg cramps.

Frequently asked questions

Is it normal to feel breathless in early pregnancy?

It can happen, and KKH links breathlessness in the second trimester to your body's growing need for oxygen. If it's sudden, severe, or comes with chest pain, palpitations, fever or dizziness, see a doctor rather than waiting it out.

When does breathlessness start in pregnancy?

KKH describes it as a very common complaint by around 27 weeks, and more frequent in the third trimester as the womb presses on the diaphragm. The same pressure can make your ribs ache; see rib pain during pregnancy.

Can anaemia make you breathless in pregnancy?

Yes. Iron deficiency is the most common cause of anaemia in pregnancy, according to SingHealth, and it can leave you tired and short of breath. Your blood count is checked at about 10 to 12 weeks and again at 24 to 28 weeks, and iron tablets are the usual treatment.

Why do I feel dizzy lying on my back?

Later in pregnancy, lying flat on your back can make you feel faint. KKH advises lying on your side after about mid-pregnancy, with a small pillow under your belly.

Is it safe to keep exercising if I get breathless?

Usually, at a gentler pace. SingHealth lists shortness of breath, dizziness, chest pain and excessive fatigue among the warning signs during exercise. Stop if they appear, and check with your doctor before you start again.