Read this first: migraine care during pregnancy is a clinical conversation, not a self-management exercise. The content below is informational, summarises what published reviews show, and explicitly does not recommend any medication or treatment. Every pregnancy-specific decision needs to involve your obstetrician — ideally before conception when possible.

With that said: most women with migraine see significant improvement during pregnancy, especially in the second and third trimesters. Understanding why, and what changes, helps both your planning and your conversations with clinicians.

The pattern most women experience

Across cohort studies of pregnancy in women with prior migraine:

  • First trimester — frequency similar to or slightly improved from baseline. Some women see worsening here, particularly with morning sickness compounding the picture.
  • Second trimester — frequency drops significantly. Roughly 50–60 percent of women with migraine report substantial improvement.
  • Third trimester — typically the lowest-frequency period. 60–70 percent improvement is the population average.
  • Postpartum (first week) — sharp return. About 30 percent of women have a migraine within the first 5 days after delivery.
  • Postpartum (first 3 months) — frequency often rises above pre-pregnancy baseline temporarily, especially in the absence of breastfeeding (which prolongs the estrogen-stable period).

This pattern aligns with the estrogen hypothesis of menstrual migraine — high and stable estrogen during pregnancy reduces attack frequency, and the abrupt postpartum drop mimics perimenstrual estrogen withdrawal.

Who doesn’t follow the pattern

A significant minority of women with migraine — perhaps 20–25 percent — see no improvement or actual worsening during pregnancy. Risk factors for not improving:

  • Migraine with aura — less responsive to the hormonal-stability effect.
  • Pre-pregnancy chronic migraine — less likely to revert to episodic during pregnancy than expected.
  • High pre-pregnancy attack frequency.
  • Concurrent depression or anxiety.

If you’re in this group, the treatment conversation is more urgent — preventive options narrow significantly during pregnancy and many require pre-conception planning.

The new pregnancy-specific risks

Migraine itself is generally safe during pregnancy — but a few specific concerns merit attention:

  • Migraine with aura is associated with higher risk of preeclampsia and stroke during pregnancy. This is a real monitoring consideration for the obstetrician, not a reason for panic.
  • New severe headache during pregnancy needs urgent evaluation — preeclampsia, cerebral venous thrombosis, and other pregnancy-specific complications can present as severe headache.
  • Postpartum severe headache — particularly within the first 6 weeks — needs urgent evaluation for the same reasons plus postpartum-specific causes (reversible cerebral vasoconstriction syndrome, pituitary apoplexy, others).

These are not hypothetical risks. The threshold for ED evaluation of a new-pattern or severe headache during pregnancy and the postpartum period should be lower than at other times.

What changes for treatment options

This is the section where we’re going to be deliberately brief and uninformative on specifics — because pregnancy-safe medication is the textbook YMYL topic where bad advice causes real harm. The framework:

  • Acetaminophen is the most commonly used first-line acute option across pregnancy. Studies generally support its safety.
  • NSAIDs have trimester-specific restrictions — generally avoided in the third trimester.
  • Triptans — pregnancy registries (largest is the sumatriptan registry) show no clear increase in major malformations, but routine use during pregnancy isn’t the default. This is a conversation with your obstetrician.
  • Most preventive medications require either continuation, modification, or discontinuation in pregnancy. Some (valproate, topiramate) have known teratogenic risk and are generally stopped pre-conception.
  • CGRP monoclonal antibodies are too new to have robust pregnancy safety data. Most are advised against in pregnancy pending data.

The decision-making process for each medication is individualised — based on attack severity, frequency, gestational age, and the specific medication’s risk profile. Hermly will not give you a yes/no on any specific medication.

Tracking during pregnancy

Hermly’s forecast model continues to work during pregnancy. A few practical notes:

  • Cycle features become inactive — Apple Health will stop registering cycle days once pregnancy is logged. Hermly handles this gracefully (the cycle factor card shows ”—”).
  • Sleep patterns shift significantly, especially in the third trimester. The personal baseline takes ~14 days to recalibrate after a significant shift.
  • Wrist temperature and HRV change with pregnancy physiology. The personal baseline adapts to these too.

If your forecast accuracy seems off in early pregnancy, that’s expected — the model needs a few weeks to recalibrate to your new physiological baseline.

Postpartum tracking

The first 6 weeks postpartum are the highest-risk period for return of attacks. Specific things worth tracking:

  • Onset time and severity of any postpartum attacks.
  • Sleep deprivation correlation — postpartum sleep is highly disrupted, and this is a major contributor to early return.
  • Breastfeeding considerations — many migraine medications have specific breastfeeding restrictions; talk to your obstetrician about this before delivery if possible.

What this isn’t

This page is not a treatment plan. It’s not a substitute for pre-conception counseling with a headache specialist if you’re planning pregnancy and have migraine. It’s not a list of “safe” medications — that determination is medication-specific, patient-specific, and changes as evidence evolves.

What it is: a framework for understanding the expected pattern and what to track, so the conversations with your obstetrician and headache specialist are well-informed.