It can be. It's one of the most common complaints . Drink plenty of water and make sure to call the doctor. Have you stopped, or cut down on caffeine recently ? Chocolate, tea, pop, coffee ? Lack of sleep, stress? Give a call to make sure all is well. Congrats!
Go see your OB right away - remember, no booze, drugs, cigarettes, weed, or any other substances or stimuli that can affect your baby. Headaches are usually associated with hypertension. Also make sure your OB tests you for pre-eclampsia, as well as ultrasounds your fetus. Make sure you're taking your neo-natal vitamins and enzymes. And stay away from stress.