Headaches are very common during pregnancy, especially during the first and third trimesters.  During the first trimester it is thought that headaches are caused by the surge of hormones and the increase in blood volume in your changing body.  These are tension headaches and can be even more bothersome if they are aggravated from stress, bad posture or if your vision changes.  Other causes of headaches during pregnancy could be lack of sleep, low blood sugar, increased hunger, dehydration and caffeine withdrawal.

If you do suffer from headaches during your pregnancy you could be very sensitive to hormones.  You can be more prone to headaches if you struggled with them prior to your pregnancy, as well. 

You should contact your doctor if you cannot get any relief from your headaches, or if the headaches get worse or more persistent.  If you have a headache that is different than normal or is accompanied by blurred vision, sudden weight gain, swelling in the hands and face or pain in the abdomen you should call your doctor right away.  During the second or third trimester of pregnancy high blood pressure can cause a rare condition known as preeclampsia.  These symptoms can be a warning sign of preeclampsia.  Headaches that are caused by high blood pressure are persistent and throbbing.  Preeclampsia only occurs in 5-10% of pregnancies.

Headaches are an unpleasant, but very common ailment while pregnant.  Most headaches will subside if you can find the cause and alleviate the problem.  If all else fails, it is usually considered safe to take an occasional acetaminophen.

Headaches during pregnancy, the causes and when to be concerned