For many women migraine attacks ease during pregnancy, and that usually starts after the first trimester. In a prospective study of 49 women with migraine, attack frequency improved in 46.8% during the first trimester, in 83.0% during the second and in 87.2% during the third (PMID 12662187).
It is one of the few moments when hormonal headache moves in the right direction.
An important boundary first: this piece is about migraine you already knew and how it behaves in pregnancy. New or differently feeling headache in pregnancy belongs with your midwife or GP, not with an article. Why, is further down.
Why does migraine often improve in pregnancy?
Because your oestrogen stops swinging. Outside pregnancy it peaks and falls each cycle, and it is that sharp drop that appears to trigger migraine attacks. During pregnancy your oestrogen stays high and stable for a long stretch. The trigger that drove your monthly attacks falls away.
Stable is the key word here, not high.
That fits the oestrogen withdrawal hypothesis, although the evidence for it is thinner than commonly assumed: small groups and inconsistent definitions (PMID 37730536). The pattern in pregnancy, meanwhile, is described strikingly consistently.
The first trimester lags behind the rest. Oestrogen is still building then, and nausea, eating less and drinking less all play a part, each a headache cause in its own right. The explanation of that hormonal side is in hormonal headache.
What happens per trimester?
The improvement grows as pregnancy progresses. In the same study, migraine even disappeared entirely for a growing share of women: 10.6% in the first trimester, 53.2% in the second and 78.7% in the third (PMID 12662187).
| Trimester | Share with fewer attacks | Share fully attack free |
|---|---|---|
| First | 46.8% | 10.6% |
| Second | 83.0% | 53.2% |
| Third | 87.2% | 78.7% |
Two caveats belong with this. The study group was small, 49 women, so the exact percentages are a direction, not a guarantee. And it held mainly for migraine without aura; women with menstrually related migraine beforehand improved less often.
For some women little changes, or the first trimester is briefly heavier instead. That also fits the picture and does not mean something is wrong.
Picture a woman who had 2 attacks a month before pregnancy, tight around her period. In the first trimester she still gets one, with the nausea on top. In the second she is attack free. Her oestrogen no longer swings, and the trigger is gone.
That is no law. But it is the pattern the research describes.
And after the birth?
Then migraine returns for many women, often quickly. In the same study, migraine came back in 34.0% within the first week after delivery and in 55.3% within the first month (PMID 12662187). The cause is straightforward: after the birth your oestrogen falls away abruptly, and that is exactly the sharp drop that triggers attacks.
Notably, breastfeeding appeared to protect against that return in that study.
Why is not certain; breastfeeding may keep the hormonal swings after birth a little flatter. How your hormones recover after pregnancy is in postpartum recovery.
Which headache in pregnancy needs prompt assessment?
New, severe or differently feeling headache, and most urgently in the second half of pregnancy. Headache in that period can be a sign of high blood pressure or pre-eclampsia, and that needs assessing. This is why I did not want to write this piece without a clear boundary.
So contact your midwife or GP promptly for:
- Severe headache that is new to you or feels different from your usual migraine.
- Headache with blurred vision, flashes of light you do not know, or spots.
- Headache with pain in your upper abdomen, nausea, or suddenly swollen hands and face.
- Headache that reaches full force within seconds.
These symptoms do not belong to the reassuring cycle story and deserve same day attention.
For your familiar migraine, which usually becomes milder in pregnancy, that does not apply in the same way. But when in doubt between the two, one call to your midwife is always the safe choice.
Does blood testing add anything here?
Not for the migraine itself, and certainly not as a replacement for your antenatal checks. You do not show migraine with blood, and the assessment of headache in pregnancy belongs with your midwife, who also measures your blood pressure. That is the main channel here, not a test.
What antenatal care does look at is, for instance, your iron, because anaemia can amplify the fatigue and headache around it.
Which values are routinely checked in pregnancy and when is in blood testing during pregnancy. If your migraine is instead climbing towards menopause rather than pregnancy, read migraine in menopause.
For headache in pregnancy, then, your midwife is the first address, and blood testing is at most an addition you discuss with her or your GP.
References
- Sances G, Granella F, Nappi RE, et al. Course of migraine during pregnancy and postpartum: a prospective study. Cephalalgia. 2003;23(3):197-205. PMID 12662187.
- Raffaelli B, Do TP, Chaudhry BA, Ashina M, Amin FM, Ashina H. Menstrual migraine is caused by estrogen withdrawal: revisiting the evidence. J Headache Pain. 2023;24(1):131. PMID 37730536.
- Reddy N, Desai MN, Schoenbrunner A, Schneeberger S, Janis JE. The complex relationship between estrogen and migraines: a scoping review. Syst Rev. 2021;10(1):72. PMID 33691790.
- Thuisarts. Migraine. Available via thuisarts.nl.
- RIVM and VZinfo. Migraine: figures and context. Available via vzinfo.nl.
Every blood test result at Lunara includes a professional assessment by a BIG-registered doctor. For treatment decisions, discuss your results with your GP or midwife.
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