Most headaches in pregnancy are the ordinary kind arriving in a body that is dehydrated, under-slept and off caffeine. One kind is not ordinary, and it is identified not by severity but by what accompanies it.
Call your maternity unit the same day if, after 20 weeks, a headache comes with any of: blurred vision, flashing lights, spots or other visual changes; sudden swelling of the face, hands or feet; pain under the ribs on the right side; vomiting; or a headache that will not go with paracetamol. That combination is how pre-eclampsia presents.
Call emergency services for a headache that comes on suddenly and is the worst you have ever had, or one with fever and a stiff neck, confusion, slurred speech, weakness on one side, or a seizure.
The short answer: tension-type headaches are common in the first trimester from hormonal change, dehydration, low blood sugar, poor sleep and caffeine withdrawal, and again in the third from tiredness and posture. Paracetamol at the lowest effective dose is the usual treatment; ibuprofen is avoided after 20 weeks. The headache that needs a call is the one with visual changes, sudden swelling or right-sided rib pain.
Why it happens
The first trimester has the steepest hormonal gradient of the whole pregnancy, and headache is a common accompaniment to that on its own. What makes it worse is everything else happening at the same time: nausea reduces how much you drink, food aversions disrupt regular eating, sleep is broken, and a great many people quit caffeine abruptly the day they see a positive test. Caffeine withdrawal alone produces several days of headache, and it is entirely avoidable — moderate caffeine intake is not prohibited in pregnancy, and tapering over a week or two is kinder than stopping dead.
Third-trimester headaches are more often postural and fatigue-driven: the change in posture loads the neck and shoulders, sleep is fragmented, and the tension-type headache follows from both. It is also the period when blood pressure needs watching, which is why a headache after 20 weeks is treated as a piece of information rather than as a nuisance.
What is normal
| Ordinary headache | Ring the same day | |
|---|---|---|
| Onset | Builds over hours | Sudden, peaking within seconds or minutes |
| Vision | Unaffected | Blurring, flashing lights, spots, loss of part of the field |
| Swelling | None new | Sudden swelling of face, hands or feet |
| Response | Eases with water, food, rest, paracetamol | Unchanged by paracetamol, or waking you from sleep |
| With it | Nothing | Vomiting, right-sided rib pain, fever, stiff neck, confusion, weakness |
Safe relief, stated as a pair
💊 What is and is not used
- Paracetamol — lowest effective dose, shortest time. The standard option throughout pregnancy.
- Ibuprofen and other NSAIDs — avoided after 20 weeks, and generally avoided before that too unless specifically advised.
- Aspirin for pain — not used. Low-dose aspirin prescribed to reduce pre-eclampsia risk is a separate thing and is continued as directed.
- Migraine-specific medicines and codeine-containing painkillers — ask before taking, rather than after.
- The non-drug half: water, something to eat, a dark quiet room, a cold compress, and a caffeine taper rather than a cliff.
Headaches in pregnancy — at a glance
Tension-type headaches are common in the first trimester, driven by the steepest hormonal change of the pregnancy plus dehydration, missed meals, broken sleep and abrupt caffeine withdrawal — the last of which is avoidable by tapering rather than stopping dead, since moderate caffeine is not prohibited. They return in the third trimester from posture and fatigue. Paracetamol at the lowest effective dose for the shortest time is the usual treatment; ibuprofen and other NSAIDs are avoided after 20 weeks and generally before, and aspirin is not used for pain, though prescribed low-dose aspirin for pre-eclampsia risk is a different matter and continues. The pattern that requires a same-day call after 20 weeks is a headache accompanied by visual changes, sudden swelling of the face or hands, right-sided pain under the ribs or vomiting — that is pre-eclampsia. A thunderclap headache, or one with fever and neck stiffness, confusion, weakness or seizure, needs emergency services rather than a call.
Inside Baby Novum: blood pressure readings are stored with their date and gestational week and plotted over time. When a headache arrives after 20 weeks, a home reading taken alongside it is the most useful single thing to have when you ring. Everything is encrypted on the device, with no account and no server holding a copy.
Frequently Asked Questions
Are headaches normal in pregnancy?
Common, yes — particularly in the first trimester, when hormone levels are changing fastest, and again in the third from tiredness, posture and dehydration. Most are tension-type: a band of pressure across the forehead or around the head, dull rather than throbbing, and eased by water, food, rest and paracetamol. Cutting caffeine abruptly on discovering a pregnancy causes a great many of them.
What painkillers can I take for a headache in pregnancy?
Paracetamol at the lowest effective dose for the shortest time is the usual choice and is generally considered suitable throughout pregnancy. Ibuprofen and other NSAIDs are avoided after 20 weeks — they can affect the baby's kidneys and the ductus arteriosus — and are generally avoided earlier too unless specifically advised. Aspirin is not used for pain in pregnancy, although low-dose aspirin is sometimes prescribed for a different reason entirely. Ask before using anything else, including migraine medication you took before.
When is a headache in pregnancy dangerous?
The pattern that matters most is a headache with something else, after 20 weeks: blurred vision, flashing lights or spots, sudden swelling of the face, hands or feet, pain below the ribs on the right, or vomiting. That combination is pre-eclampsia until proven otherwise and needs a same-day call. Also urgent on its own: a headache that comes on suddenly and is the worst you have had, or one with fever, a stiff neck, confusion, weakness or a seizure.
Do migraines get better or worse in pregnancy?
For many people migraines improve, particularly after the first trimester, because the oestrogen fluctuation that triggers them is replaced by sustained high levels. Some get worse, and some experience their first migraine in pregnancy. If you take migraine medication, ask before continuing — some options are used in pregnancy and others are not, and a new visual aura in pregnancy should be reported rather than assumed to be a migraine.
What causes headaches in the first trimester?
A combination that is easy to fix and easy to overlook: the hormonal shift itself, dehydration if you are nauseated and drinking less, low blood sugar from skipped meals, poor sleep, and caffeine withdrawal. Cutting from several coffees a day to none overnight reliably produces days of headache — tapering over a week or two avoids it, and moderate caffeine is not forbidden in pregnancy.