The short explanation
Please do not assume this is tiredness. In the second half of pregnancy, a headache with blurred vision or flashing lights can be a warning sign of pre-eclampsia, a condition where blood pressure rises and can affect the mother and baby. It needs to be checked today, not at your next routine visit. Doctors will check your blood pressure and urine, ask about swelling and other symptoms, and may do blood tests and monitor the baby. Many women with these symptoms are found to have something less serious, but pre-eclampsia can get worse quickly, so it is important to be seen promptly.
What depends on your situation
The parts of this that change from woman to woman. Uncertainty is stated, not hidden.
- Other warning signs include swelling of the face, hands or feet that appears suddenly, pain under the ribs on the right side, vomiting, and feeling very unwell.
- Women with high blood pressure before pregnancy, first pregnancies, twins, diabetes, kidney disease or previous pre-eclampsia are at higher risk.
- Mild changes in vision can happen in pregnancy, but sudden blurring or flashing lights should always be checked.
- Government hospitals have labour wards that can assess you at any time of day or night.
What this answer cannot determine
The boundary of online education. These need a clinician who can see you.
- This cannot tell you whether you have pre-eclampsia or another cause. You need to be examined and have blood pressure and urine tests today.
Questions for your clinician
Take these with you. You can add any of them to an appointment card.
- Is my blood pressure raised?
- Are there signs of pre-eclampsia in my tests?
- Is the baby doing well?
- What symptoms should make me come back immediately?
When to seek help
Clinician-approved guidance for this topic. When in doubt, being seen is never the wrong choice.
Emergency — call 112 now
- Call 112 or go to the labour ward or emergency now if you have severe headache, blurred vision or flashing lights, pain under the ribs, fits, or breathlessness.
Get help the same day
- Even if symptoms ease, get your blood pressure checked the same day.
Sources
The evidence this explanation is built on.
- Eye care MedlinePlus (US National Library of Medicine)
- Eye diseases MedlinePlus (US National Library of Medicine)
- Vision impairment and blindness MedlinePlus (US National Library of Medicine)
Who wrote and reviewed this
Every AskHer answer names its author. A clinically reviewed answer also names the clinician who signed it off — if no clinician is named below, it has not been clinically reviewed.
- Author
- AskHer Editorial (AI-assisted draft) AskHer's editorial team — not an individual clinician Works in English, தமிழ், हिन्दी
- Clinical reviewer
- Nobody yet No clinician has signed this answer off, and no person on the editorial team has read it yet. That is what the “Written with AI assistance” label means. It is queued for an editor to read, and then for a clinician who works in this area. The sources it was drafted against are listed above.
- Review status
- Written with AI assistance — not yet reviewed by a person
- Last reviewed
- Not yet reviewed by a person
- Version
- 1
Correction history
Substantive changes are listed, not quietly edited away.
No corrections have been made since this answer was first published.
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