Pregnancy Headaches: Causes, When to Worry, and Safe Relief

Headaches are among the most common complaints during pregnancy, particularly in the first and third trimesters. For most women they are an inconvenient but benign symptom driven by the hormonal and physiological changes of pregnancy. For a small number of women, a headache during pregnancy is a warning sign of a serious condition that requires prompt medical attention.

Knowing which is which matters. This guide covers the common causes of pregnancy headaches, what is safe to take for relief, and the specific symptoms that mean you should contact your GP or go to hospital rather than reaching for paracetamol and lying down.

Common causes of pregnancy headaches

Hormonal changes

The most common cause of headaches in the first trimester is the dramatic shift in oestrogen and progesterone that occurs as pregnancy establishes. These hormonal changes affect blood vessel tone and pain sensitivity in ways that can trigger headaches even in women who rarely experience them outside of pregnancy. First trimester headaches driven by hormonal change tend to ease as the hormonal environment stabilises in the second trimester.

Dehydration

Your blood volume increases by around 50 percent during pregnancy, which significantly increases your fluid requirements. Inadequate hydration is one of the most consistently preventable causes of pregnancy headaches. Many women who develop frequent headaches in pregnancy find that simply increasing their fluid intake to around 2.3 litres per day produces a meaningful reduction. Dehydration headaches typically present as a dull, persistent ache rather than a sharp or throbbing pain.

Caffeine withdrawal

Many women reduce or eliminate caffeine at the start of pregnancy. If you were previously drinking two or more cups of coffee per day, reducing this suddenly can trigger withdrawal headaches that last several days to a week. Tapering caffeine gradually rather than stopping abruptly reduces this effect. The Australian recommendation during pregnancy is to limit caffeine to no more than 200 milligrams per day, roughly equivalent to one standard espresso.

Tension headaches

The postural changes of pregnancy, including the forward shift in centre of gravity and the increased curve of the lower back, create sustained tension in the neck and upper back muscles that can refer pain into the head. Poor sleep, stress, and prolonged screen use compound this. Tension headaches typically feel like a band of pressure around the head or a tightening at the temples and back of the skull.

Low blood sugar

Pregnancy increases the metabolic demands on your body and makes blood sugar less stable for many women, particularly if meal timing is irregular. Headaches that occur when you have gone several hours without eating, that improve after eating, or that coincide with nausea and lightheadedness may reflect blood sugar fluctuation. Small, frequent meals help manage this.

Sinus congestion

Increased blood volume during pregnancy causes the mucous membranes to swell, which commonly produces nasal congestion. This congestion can drive sinus pressure headaches, particularly in the frontal area of the face and forehead. Saline nasal rinses are safe during pregnancy and can relieve sinus congestion without medication.

Sleep disruption

Poor sleep is both a cause and consequence of pregnancy headaches. Sleep deprivation lowers the pain threshold and increases susceptibility to headache. If frequent overnight waking from hip pain, heartburn, or restless legs is significantly disrupting your sleep, addressing those specific causes reduces headache frequency alongside improving overall sleep quality.

What is safe to take for headaches during pregnancy in Australia

Paracetamol

Paracetamol is the recommended first-line pain relief for headaches during pregnancy in Australia. It is considered safe at standard doses when used as directed. Take the lowest effective dose for the shortest time needed rather than taking it preventively or continuously.

There has been some research suggesting a possible association between long-term, high-dose paracetamol use during pregnancy and developmental outcomes in children. The key phrase is long-term and high-dose — occasional use at standard doses for headache relief is not what this research addresses. If you have concerns, discuss them with your GP or midwife rather than avoiding all pain relief.

What to avoid

Ibuprofen and other anti-inflammatory medications are not recommended during pregnancy, particularly from 20 weeks onwards. Aspirin is generally not recommended for pain relief during pregnancy at standard doses. Codeine-containing products require specific medical guidance during pregnancy. Do not take any medication for headaches during pregnancy without confirming it is appropriate with your GP, midwife, or pharmacist.

Non-medication approaches

Many pregnancy headaches respond well to simple non-pharmacological measures. Rest in a quiet, dark room. A cool cloth applied to the forehead or the back of the neck. Drinking a large glass of water immediately — dehydration headaches respond quickly to rehydration. Gentle neck and shoulder stretches to release tension. A warm shower. If nausea is also present, fresh air and a small amount of food alongside fluid often helps.

Prevention: reducing the frequency of pregnancy headaches

Several consistent habits reduce the frequency of pregnancy headaches significantly for most women.

Staying well hydrated throughout the day is the most impactful single change. Aim for around 2.3 litres of fluid per day from all sources. Water, diluted juice, herbal teas that are safe during pregnancy, and fluid from food all contribute.

Eating small, frequent meals prevents the blood sugar fluctuations that trigger headaches in susceptible women. Going more than three to four hours without eating is worth avoiding if headaches are frequent.

Managing screen time and posture reduces tension headache frequency. Setting up your work environment so your screen is at eye level rather than below it reduces the neck flexion that drives tension in the upper back and neck.

Adequate sleep, addressed through good sleep positioning and a consistent wind-down routine, reduces headache susceptibility across the board.

Regular gentle exercise, including walking and prenatal yoga, improves circulation, reduces muscle tension, and supports better sleep — all of which contribute to headache prevention.

When a headache during pregnancy is a warning sign

This section is the most important one in the post and worth reading carefully.

Headaches during pregnancy are occasionally a symptom of pre-eclampsia, a serious condition involving high blood pressure and organ involvement that affects around five percent of pregnancies. Pre-eclampsia can develop rapidly and, if untreated, can become life-threatening for both mother and baby. It is most common in the second half of pregnancy, particularly from 20 weeks onwards.

The headache associated with pre-eclampsia is typically described as severe and persistent — different in quality or intensity from headaches you have experienced before in pregnancy or outside of it. It is often described as a pounding or pressure behind the eyes or across the forehead that does not respond to paracetamol.

Contact your midwife, GP, or maternity assessment unit promptly — or go directly to hospital if you cannot reach them quickly — if you experience any of the following.

A severe headache that is different from your normal headaches or that does not ease with rest and paracetamol. Visual disturbances alongside a headache, including blurred vision, seeing spots or flashing lights, or sudden changes in vision. Sudden severe swelling of the face, hands, or feet alongside a headache. Pain in the upper right abdomen or below the ribs alongside a headache. Nausea and vomiting that appears suddenly alongside a severe headache rather than as part of ongoing first trimester nausea.

These symptoms can indicate pre-eclampsia, HELLP syndrome, or other serious conditions that require urgent assessment. Do not wait and see if they improve. Do not take paracetamol and lie down and hope for the best. Contact your care team promptly.

If you are ever unsure whether your headache warrants medical attention during pregnancy, the correct answer is to call your midwife or maternity assessment unit and describe your symptoms. They would always rather reassure you than have you sitting at home with a symptom that needed assessment.

Headaches in the third trimester specifically

Headaches in the third trimester warrant a lower threshold for contacting your care team than headaches in the first or second trimester, because pre-eclampsia most commonly develops in the second half of pregnancy. A headache in the first trimester that is clearly related to hormonal change, dehydration, or caffeine withdrawal carries a different implication than a new or severe headache at 32 weeks.

This does not mean every third trimester headache requires an urgent call. It means that if you are uncertain, you contact your midwife rather than managing it at home and hoping it resolves.

Blood pressure monitoring becomes more frequent in the third trimester for this reason. If you have a home blood pressure monitor, measuring your blood pressure when a headache develops and reporting the reading alongside your symptoms gives your care team more useful information.

Migraines during pregnancy

Women with a history of migraines before pregnancy may find that their migraine pattern changes significantly during pregnancy. Some women experience fewer migraines, particularly in the second trimester, as oestrogen levels stabilise. Others find that migraines continue or become more frequent.

Managing migraines during pregnancy is more complex than managing tension or dehydration headaches because many standard migraine medications are not safe during pregnancy. If you have a pre-existing migraine condition, discuss your management plan with your GP or neurologist before or early in pregnancy so you have a clear protocol for when migraines occur rather than making decisions during an episode.

Triggers for migraines — including poor sleep, dehydration, skipped meals, strong smells, and stress — overlap significantly with the general headache prevention strategies above. Managing these consistently reduces migraine frequency for many women.