Headaches in Early Pregnancy: Causes & When They Start

Headaches in early pregnancy are caused by a combination of hormonal, physical and lifestyle changes that occur rapidly after conception. Several things happen at once in the early weeks that together make headaches more likely than at other points in the cycle.

The sharp rise in oestrogen and progesterone that follows implantation is the primary driver. Oestrogen in particular is known to affect the blood vessels in the brain, causing them to dilate and contract in ways that can trigger headaches. The rapid hormonal fluctuations of early pregnancy — particularly in the first trimester before hormone levels stabilise — make headaches a very common complaint.

Increased blood volume is another contributing factor. From very early in pregnancy the body begins producing significantly more blood to supply the developing embryo, which increases pressure in the blood vessels and can trigger headaches. Changes in blood pressure, blood sugar levels and sleep patterns in early pregnancy all add to the picture.

Headaches can begin as early as 7-14 DPO in some women — right in the middle of the two week wait — which is around the time of implantation and the initial rise in pregnancy hormones. For many women they are one of the first symptoms they notice, sometimes even before a missed period.

For most women headaches become more noticeable in the weeks following a missed period as oestrogen levels rise rapidly. The first trimester is typically when pregnancy headaches are most frequent and intense, with many women finding they improve in the second trimester as hormone levels stabilise.

It is worth noting that headaches in the luteal phase are also common in non-pregnant cycles — many women experience headaches in the days before their period as a normal PMS symptom. This makes headaches before a missed period particularly hard to interpret in the TWW.

Pregnancy headaches can vary significantly in character and intensity between women. Some women experience mild tension-type headaches while others find the headaches are more intense and debilitating. The most common type of pregnancy headache is a tension headache — a dull, aching pressure that affects both sides of the head.

Some women who are prone to migraines find their migraines worsen in early pregnancy due to the hormonal changes, while others find they actually improve. This is highly individual and largely depends on the hormonal triggers specific to each woman.

• A dull, aching pressure on both sides of the head
• Tightness or pressure across the forehead or temples
• Pain that radiates from the neck or shoulders into the head
• Sensitivity to light or noise alongside the headache
• Headaches that are worse in the morning or on waking
• Headaches triggered by strong smells — linked to hyperosmia in early pregnancy
• Headaches that come and go throughout the day
• Headaches accompanied by nausea

This is one of the more difficult distinctions to make because pregnancy headaches do not have a unique character that sets them apart from headaches caused by other things. A tension headache caused by early pregnancy hormones feels very similar to a tension headache caused by dehydration, stress or poor sleep.

The most meaningful difference is context. If you are in the TWW and experiencing headaches that are more frequent or more intense than your usual pattern — particularly alongside other possible early pregnancy symptoms — it is worth paying attention to. A headache that is new, persistent and not explained by obvious factors like dehydration or poor sleep in the right window of your cycle is worth noting.

The key question is whether the headache fits a pattern you recognise from previous non-pregnant cycles. If you regularly get premenstrual headaches, a headache before a missed period is less meaningful than if you rarely get headaches and suddenly develop them in your TWW.

• Pregnancy headache: more frequent than your usual pattern
• Normal headache: fits a recognised pattern from previous cycles
• Pregnancy headache: not fully explained by obvious triggers like dehydration
• Normal headache: resolves with hydration, rest or pain relief
• Pregnancy headache: may be accompanied by other early pregnancy symptoms
• Normal headache: isolated symptom without other early pregnancy signs
• Pregnancy headache: persists or recurs over several days
• Normal headache: typically resolves within a few hours

Understanding the most common triggers for headaches in early pregnancy can help you both identify what is causing yours and take steps to manage them. Many pregnancy headaches are driven by factors that can be addressed with simple lifestyle adjustments.

Dehydration is one of the most significant triggers. Blood volume increases dramatically in early pregnancy and the body's fluid requirements increase accordingly. Many women do not keep up with this increased demand, leading to mild dehydration that can trigger headaches.

Low blood sugar is another common trigger, particularly in women who are experiencing nausea and food aversions that make it difficult to eat regularly. Skipping meals or going long periods without eating can cause blood sugar to drop and trigger a headache.

• Dehydration — the most common and easily addressed trigger
• Low blood sugar from skipped meals or nausea-related food avoidance
• Caffeine withdrawal — particularly relevant if you have cut back on caffeine since TTC
• Hormonal fluctuations — oestrogen and progesterone directly affecting blood vessels
• Poor sleep or disrupted sleep patterns
• Stress and anxiety — very common during the TWW
• Strong smells triggering headaches alongside hyperosmia
• Tension in the neck and shoulders from fatigue or poor posture
• Changes in blood pressure in early pregnancy

Headaches before a missed period are one of the more ambiguous early pregnancy symptoms because they are also a very common PMS symptom. Many women experience headaches in the days before their period as a normal part of their cycle, driven by the drop in oestrogen that occurs premenstrually.

The premenstrual headache caused by falling oestrogen feels different from the early pregnancy headache caused by rising oestrogen — but in practice the distinction can be very hard to make in the moment. The most reliable indicator remains what follows: if your period arrives, the headache was likely PMS related. If it does not, a pregnancy test is worth taking.

One clue that some women describe is that premenstrual headaches tend to resolve once the period starts, while early pregnancy headaches continue and may intensify in the weeks that follow. If you have a headache that persists past when your period would normally be due alongside other symptoms, it is worth testing.

Understanding when pregnancy-related headaches can realistically begin helps to give context to any symptoms you are experiencing during the TWW. Here is a rough guide by DPO:

• 1-5 DPO: Headaches at this stage are not pregnancy related. Implantation has not yet occurred and pregnancy hormones are not present.
• 6-8 DPO: Implantation is occurring. Oestrogen is beginning to rise. Very early pregnancy headaches could theoretically begin around this point in some women.
• 9-10 DPO: HCG is rising after implantation. Some women report the first hints of unusual headaches around this time alongside other early symptoms.
• 11-12 DPO: HCG and oestrogen are rising rapidly. Headaches that are more frequent or intense than your usual pattern at this stage are worth noting.
• 13-14 DPO: Around the time of a missed period. Headaches that have continued or worsened as your period would normally be due lean more toward early pregnancy.
• After missed period: Persistent and recurring headaches after a missed period are a well recognised first trimester symptom.

One of the most common but often overlooked causes of headaches in the early weeks of pregnancy — or even in the TWW before a positive test — is caffeine withdrawal. Many women reduce or eliminate caffeine when TTC or as soon as they think they might be pregnant, and caffeine withdrawal is a well recognised cause of significant headaches.

Caffeine withdrawal headaches typically begin within 12-24 hours of reducing or stopping caffeine and can be quite intense. They tend to be felt as a throbbing pain across the forehead and are often accompanied by fatigue, irritability and difficulty concentrating.

If you have recently reduced your caffeine intake and are experiencing headaches, this is a very likely explanation — particularly if the headaches began around the same time as the caffeine reduction. Tapering caffeine intake gradually rather than stopping abruptly can help minimise withdrawal headaches.

For women going through IVF, headaches are extremely common throughout the treatment cycle and can be caused by a number of factors. The hormonal medications used during stimulation and the two week wait — including GnRH agonists, oestrogen supplements and progesterone — all commonly cause headaches as side effects.

This makes it very difficult to attribute headaches in the two week wait after a transfer specifically to early pregnancy rather than medication effects. Many women going through IVF experience significant headaches throughout the process regardless of whether a transfer is successful.

As with all symptoms in the IVF two week wait, headaches cannot reliably indicate whether a transfer has worked. The only way to know is through a blood test or home pregnancy test at the appropriate time.

While headaches are a common and usually benign early pregnancy symptom, it is important to be aware of when a headache in pregnancy could be a warning sign that requires medical attention.

A sudden, severe headache that comes on very rapidly and feels unlike any headache you have had before — sometimes described as a thunderclap headache — should always be assessed by a doctor immediately as it can occasionally indicate a serious condition.

Later in pregnancy, persistent severe headaches — particularly in the second or third trimester — can be a sign of pre-eclampsia, a serious pregnancy complication that also causes high blood pressure, swelling and visual disturbances. Any severe or unusual headache in pregnancy is always worth mentioning to a midwife or doctor.

• A sudden severe headache unlike any you have experienced before — seek urgent medical attention
• Headache accompanied by visual disturbances, swelling or high blood pressure — may indicate pre-eclampsia
• Headache with fever — may indicate infection
• Headache accompanied by stiff neck — seek urgent medical attention
• Headache that does not respond to safe pain relief and is getting worse
• Headache after a fall or head injury during pregnancy

Managing headaches in early pregnancy requires a slightly different approach than at other times because many common headache medications are not recommended during pregnancy. It is always worth checking with a doctor or midwife before taking any medication in early pregnancy.

Paracetamol is generally considered safe for use in pregnancy and is the most commonly recommended pain relief for headaches in the first trimester. Ibuprofen and aspirin are not recommended during pregnancy, particularly in the first and third trimesters.

Non-medication approaches to managing pregnancy headaches include staying well hydrated, eating regular small meals to keep blood sugar stable, resting in a dark quiet room, applying a cold or warm compress to the forehead or neck, and gentle neck and shoulder stretches to relieve tension.

• Stay well hydrated — drink plenty of water throughout the day
• Eat regular small meals to keep blood sugar stable
• Rest in a dark quiet room when a headache strikes
• Apply a cold compress to the forehead or a warm compress to the neck
• Gentle neck and shoulder stretches to relieve muscle tension
• Paracetamol is generally considered safe — always check with a doctor first
• Avoid ibuprofen and aspirin during pregnancy
• Try to identify and avoid your personal headache triggers
• Reduce caffeine gradually rather than stopping abruptly

If you are experiencing headaches that are more frequent or intense than your usual pattern alongside other possible early pregnancy symptoms, taking a pregnancy test at the right time is the most reliable next step.

The earliest most sensitive pregnancy tests can detect HCG is around 10-12 DPO, but for the most accurate result it is worth waiting until the day of your missed period and testing with your first morning urine. FMU is the most concentrated of the day and gives the best chance of detecting low levels of HCG in very early pregnancy.

If you test and see a very faint line do not dismiss it. A line that appears within the reading window of the test — no matter how faint — is still a positive result. Retest in 48 hours and the line should be noticeably darker as HCG levels continue to rise.

A faint line on a pregnancy test in those very early days after implantation is incredibly common — HCG levels are still low and the line on a test can be almost impossible to see even when you are genuinely pregnant. This is one of the most stressful parts of the TWW and something the TTC community discusses constantly.

Enhancing your test photo by adjusting brightness, contrast and using a red light filter can make even the faintest lines much easier to see. Saving your tests and comparing them side by side over several days is also hugely reassuring — a line that gets progressively darker confirms that HCG is rising as it should.

ClearLine is an iOS app that uses AI to analyse your pregnancy test photo and detect even the faintest lines. It includes image enhancement tools, a gallery to save and track all your tests over time, and a side by side comparison feature to help you watch the line progression — everything you need to make sense of those early uncertain results.