Most women complain of constant and annoying pregnancy headaches. These headaches may occur at any time during the pregnancy, but they usually appear during the first and third trimesters, according to the American Pregnancy Association. During the first trimester, a woman may have headaches as a result of surging hormones and increased blood volume caused by rapidly changing hormone levels. Pregnancy headaches tend to be triggered by a combination of stress, poor posture and changes in vision.
Many women experience tension headache throughout their pregnancy, but it can be especially dreadful during the first trimester, according to the Utah Department of Health. Tension headaches resemble a squeezing pain or a steady dull ache on both sides of the head or the back of the neck. These types of headaches are usually caused by a lack of sleep, depression and/or caffeine withdrawal. Rising hormone levels may also trigger tension headaches, in some women.
Many women experience migraine headaches during pregnancy. Approximately 15 percent of migraine sufferers get their first migraine during pregnancy, according to website Baby Center. While the exact cause of migraines is unknown, it is believed that increased blood flow in the brain contributes to the onset and progression of these headaches. Migraines usually appear during the first trimester, but they can also occur later in the pregnancy. These types of headaches can cause moderate to severe throbbing pain, typically on one side of the head. They can last up to 72 hours and tend to be triggered by physical activity. Migraine headaches may consist of nausea, vomiting and/or sensitivity to light and noise, according to the Utah Department of Health. They usually occur less frequently after the first trimester, but some women report that their migraine headaches worsen or stay the same while they are pregnant.
A persistent severe headache during the second or third trimester of pregnancy may be a warning sign of preeclampsia. Preeclampsia, a rare condition, affects approximately 5 to 10 percent of pregnancies, according to the Utah Department of Health. Preeclampsia headaches are characterized by high blood pressure and excess protein in the woman's urine. These headaches consist of a persistent, dull or throbbing pain that does not go away. The March of Dimes states that preeclampsia headaches are usually accompanied by blurred vision, floating spots, sudden weight gain, upper right abdomen pain and/or swelling in the hands and face.