Smog and Pregnancy: What to Limit and When to Call Your Doctor
The evidence on smog and pregnancy is still uncertain, so the sensible steps are simple ones you can check on a bad air day. This guide covers what the 2025 UK review found, the daily checks to make, and the symptoms that mean a same-day call to your maternity unit.
The short version
- What is known: Some evidence suggests fine particles and ozone in outdoor air may be linked to birthweight, early birth and stillbirth, but not strongly enough for policy.
- Each morning: Check the AQI before you plan a walk.
- Bad air days: Keep windows closed, run a purifier in the room you use most, and move walks indoors or to a cleaner time.
- Call your maternity unit straight away: For reduced baby movement, a severe headache, or chest pain. For a fever of 38C or higher, seek medical advice promptly.
- Rule of thumb: Closed windows, cleaner indoor air and one phone call to your midwife at the first warning sign are the sensible plan.
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What does the evidence say about smog and pregnancy?
A review by COMEAP, the UK government’s Committee on the Medical Effects of Air Pollutants, published on 20 November 2025, looked at outdoor air pollution and birth outcomes. It found some evidence that small particles (PM2.5 and PM10) and ozone might be linked to birthweight, being born early and stillbirth. The authors did not consider that evidence robust enough for government to base policy on, and they said more research is needed on how air pollution affects the outcome of a pregnancy. That is a reason for care, not a reason to panic.
No herb, supplement or cleansing product is a smog answer. Masks and any medicines are decisions for your own obstetrician, who knows your health history.
What can you check on a bad air day?
- Check the AQI each morning, before you plan the day’s walk. The AQI numbers explained guide shows what the readings mean.
- On a bad air day, move walks indoors or to a cleaner time of day, and keep them short.
- Keep windows closed while the air is bad, and run a purifier in the room where you spend most of your time.
- Keep incense, candles and frying smoke away from the room where you rest and sleep.
- Write down the AQI for the day of any symptom, so your midwife can see a timeline.
- Do not start, stop or change a mask or medicine on your own. Ask your obstetrician first.
When should you call your maternity unit?
Match the symptom to the row. These rows follow NHS, RCOG and trust guidance, and your own unit’s number and rules come first.
| Symptom | What the guidance says | Who to contact |
|---|---|---|
| Baby moving less or differently | Get help straight away, and do not wait until the next day after 28 weeks | Midwife or maternity unit now |
| Light bleeding, no pain or mild tummy pain | Call your maternity unit; under 20 weeks, an early pregnancy unit may help | Maternity unit, or NHS 111 if you cannot reach one |
| Heavy bleeding, severe tummy pain, shoulder pain, or feeling faint | Call 999 | 999 |
| Temperature of 38C or higher | Seek medical advice promptly, as treatment may be needed | Maternity unit or doctor |
| Chest pain, or a severe headache, especially with blurred vision, swelling or pain below the ribs | Contact your midwife or maternity unit immediately | Maternity unit now |
What should you do if your baby moves less on a smoggy day?
Treat it as a call, not a wait-and-see. The RCOG leaflet says that if movements seem reduced or changed, you should seek professional help immediately, and that after 28 weeks you must not wait until the next day. It also says there is no specific number of movements that counts as normal, and that you should not rely on home heartbeat kits. Smog does not change that rule. Your own sense of your baby’s usual movements is the best guide, and a call is the safer choice when you are unsure.
The two-line diary
Keep a note on your phone with three details: the day’s AQI, any symptom, and the time it started. A simple timeline like this lets your midwife or doctor see a pattern quickly, and it takes about a minute a day.
Can a cough or wheeze from smog wait for your next appointment?
A cough or wheeze that does not settle, or any fever, is a question for your doctor or maternity unit to raise promptly rather than at a routine visit. For the breathing warning signs that apply to everyone, read smog cough, asthma or chest infection. For pregnancy headaches and when they need a call, read headache in pregnancy.
Call 999 for heavy bleeding, severe tummy pain, shoulder pain, feeling faint or dizzy, or trouble breathing while you are resting. Outside the UK, call your local emergency number: 1122 in Pakistan or 112 in India. Use your own maternity unit’s number and advice first. No herb, supplement or cleansing product replaces a check-up, and nothing in this guide replaces your obstetrician.
Smog and pregnancy questions, answered
Smog effect on pregnancy: what is known?
Some evidence suggests outdoor air pollution may be linked to birthweight, early birth and stillbirth, but a UK review published in November 2025 did not consider that evidence robust enough for policy decisions. The honest position is that the link is uncertain.
Pregnancy mein smog ka asar kya hota hai?
The evidence is still uncertain. The practical steps are closed windows, cleaner indoor air, and a call to your maternity unit at any warning sign rather than waiting.
Can smog harm an unborn baby?
The evidence is not settled either way, so the sensible approach is to reduce your exposure where you can and tell your obstetrician about any symptom. Ask your obstetrician about your own risk, since your history matters more than a general figure.
Mask for pregnant women in smog?
This guide does not recommend a mask. Ask your obstetrician, who can advise on the right type and fit for your own health.
Is it safe for a pregnant woman to walk in smog?
On a bad air day, move the walk indoors or to a cleaner time. If you feel breathless, unwell or get chest pain, stop and get help.
AQI bad in pregnancy: what to do?
Check the AQI each morning, keep the windows closed on bad days, and call your maternity unit about any symptom rather than waiting to see if it passes.
Pregnancy cough and smog: when to see a doctor?
Ask your doctor or maternity unit promptly about a cough that does not settle or any fever of 38C or higher. Trouble breathing while resting needs a 999 call.
What if your baby moves less on a smoggy day?
Call your midwife or maternity unit straight away. The RCOG leaflet says you must not wait until the next day after 28 weeks, and there is no specific number of movements that counts as normal.
Is there a herb or supplement for smog in pregnancy?
No. No herb, supplement or cleansing product is a smog answer, and none should replace advice from your obstetrician.
Where should you read next?
This article sits in the Season Shift series on what to change when the air turns. Keep the daily checks short and the call to your unit quick, and let the AQI reading guide the walk, not the other way round.
Sources
- Effects of maternal exposure to ambient air pollution on adverse birth outcomes: lay summary (Committee on the Medical Effects of Air Pollutants, 20 November 2025)
- Your baby’s movements in pregnancy (Royal College of Obstetricians and Gynaecologists)
- Vaginal bleeding in pregnancy (NHS)
- Common pregnancy symptoms or complications (Milton Keynes University Hospital NHS Foundation Trust)