Headaches in Pregnancy — and When They Signal Something Serious

When to call

Contact your maternity unit, GP or urgent care line immediately — the same hour — if you have a headache together with any of these:

• The headache is severe, or does not go away with simple painkillers.
• Problems with vision — blurring, or seeing flashing lights or spots.
• Pain just below your ribs, or in the upper abdomen or shoulder.
• Vomiting, or nausea in the second half of pregnancy.
• A sudden increase in swelling of your face, hands, feet or ankles.
• Feeling severely unwell, or sudden difficulty breathing.

The NHS lists exactly these as reasons to contact your maternity unit, GP or NHS 111 immediately, because they may indicate pre-eclampsia. The RCOG's wording is: "These symptoms can be serious and you should seek medical help immediately if you develop any of them." ACOG, for readers outside the UK, says: "If you have any of these symptoms, especially if they develop in the second half of pregnancy, call your ob-gyn right away." The HSE tells people to contact their midwife, GP or obstetrician immediately for "a severe headache — especially with other symptoms including blurred vision, upper stomach pain, nausea or swelling."

Tommy's does not hedge either: pre-eclampsia "needs to be checked immediately" and "can be dangerous for you and your baby if it is not treated."

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 a seizure, collapse, lose consciousness, or develop sudden severe breathlessness or chest pain.

Two things worth knowing before you talk yourself out of ringing. Pre-eclampsia usually appears after 20 weeks, but both the NHS and ACOG note it can also develop for the first time in the days or weeks after the birth — so the same rules apply postnatally. And you do not need to be sure. Being checked involves a blood pressure reading and a urine test, and takes minutes.

Why a headache carries this much weight

Because of what it can be a symptom of, and how quickly that condition can change.

• The RCOG says pre-eclampsia "is a condition that affects between 1-5 in 100 pregnant women", affecting up to 5 in 100 in a first pregnancy and fewer than 2 in 100 in a second.
• "Around one in 200 women develop severe pre-eclampsia, which can be life-threatening for both you and your baby" (RCOG).
• An eclamptic fit is rare — the RCOG puts it at "only one in 3000 pregnancies in the UK" — but it is what the urgency is designed to prevent.
• ACOG notes pre-eclampsia can cause HELLP syndrome, which "is a medical emergency. Women can die from HELLP syndrome."

ACOG lists among the "severe features" of worsening pre-eclampsia: severe headache, changes in vision, pain in the upper abdomen, abnormal kidney or liver function, low platelets, fluid in the lungs, and a systolic pressure of 160 mm Hg or higher or diastolic of 110 mm Hg or higher.

Here is the part most headache articles leave out. The RCOG: "Often you will have no symptoms and pre-eclampsia may be diagnosed for the first time at your routine antenatal appointments or during labour when you have your blood pressure checked and your urine tested." The two earliest signs — raised blood pressure and protein in your urine — produce no sensation at all.

Which means the headache is one route in, and your antenatal appointments are the other. Attending them is the actual screening programme.

What ordinary pregnancy headaches are

Most of them, and the picture is reassuring. The NHS: "Headaches can be common in early pregnancy. They usually improve as your pregnancy goes on." They do not harm your baby.

Tommy's names the usual causes: "Mild headaches are common in pregnancy. They can be caused by hormones or dehydration."

The pattern that suggests an ordinary headache: it is mild to moderate, it responds to paracetamol, it is not accompanied by visual changes or rib pain, and it fits a recognisable trigger — a poor night's sleep, a long stretch without drinking, hours at a screen, or skipped meals.

If you get migraines

Tommy's describes migraine as "a severe throbbing, pounding or pulsing headache" with nausea, sensitivity to light, and sometimes visual auras. Its advice is to discuss any changes in your migraines with your doctor, because some migraine medicines are not safe in pregnancy.

Migraine with aura creates a genuine dilemma, because visual disturbance is also a pre-eclampsia sign. The practical answer: tell your midwife early that you get migraine with aura, so it is on your record. And treat a headache that is different from your usual pattern — more severe, lasting longer, or with new symptoms — as a reason to get your blood pressure and urine checked rather than to assume it is a migraine.

What actually helps

Paracetamol

The NHS names paracetamol as the recommended first-line painkiller in pregnancy, with the qualifier: "for safety, if you take paracetamol in pregnancy, take it for the shortest possible time." Ask your pharmacist, midwife or GP about the right dose. Tommy's: "You can take paracetamol safely for headaches in pregnancy. Do not take more than the dose listed on the pack."

The NHS also addresses a worry many people have encountered online: the MHRA has confirmed that paracetamol use during pregnancy remains safe, with no evidence linking it to autism in children.

What to avoid

The NHS advises avoiding painkillers containing codeine, and NSAIDs like ibuprofen, unless specifically prescribed by your doctor. Tommy's: "Do not take aspirin during pregnancy unless a doctor or midwife prescribes it for you."

That last point needs a clarification, because it confuses people. Low-dose aspirin is prescribed in pregnancy — but as a preventive for pre-eclampsia, not as a painkiller. The RCOG advises aspirin at 75–150 mg once a day from 12 weeks until 36 weeks for women at higher risk, and ACOG says low-dose aspirin may reduce the risk of pre-eclampsia in some women, while adding: "Do not start taking aspirin on your own without talking with your ob-gyn." Prescribed preventive aspirin and self-medicating with aspirin for a headache are two entirely different things.

Prevention and comfort

NHS suggestions: "drink plenty of fluids to prevent dehydration", prioritise adequate sleep, and use relaxation techniques such as pregnancy yoga. Tommy's adds a healthy balanced diet, screen breaks and relaxation techniques, and for the headache itself: rest in a dark room, and use cooling strips or a cold flannel on your forehead.

Be realistic about the strength of this advice. These are sensible measures from national guidance, not treatments tested in trials on pregnancy headache specifically. Hydration and sleep are worth doing regardless; nobody has shown they reliably prevent headaches.

Other headaches that need a call

Not every concerning headache is pre-eclampsia. Contact your midwife, doctor or urgent care line if your headache comes with:

• A temperature of 38°C (100.4°F) or above. The NHS notes a high temperature can be a sign of infection and needs checking.
• Sudden breathlessness, or breathlessness lying down, or with chest pain or dizziness — the NHS says this "needs to be checked immediately".
• Any change in your baby's movements.

And if a headache is simply relentless — days long, unresponsive to paracetamol, stopping you functioning — that is worth a call in its own right, whatever the cause turns out to be. The threshold for being assessed in pregnancy is deliberately low, and using it is not an overreaction.