Is constipation normal in 3 weeks of pregnant?

Depends on severity: But, no - it isn't common just due to pregnancy. Drink water regularly - at least 8-10 8oz glasses a day. Maybe eat a few prunes or drink some prune juice for a few days. Don't use OTC laxatives w/o talking w/ your doctor. And don't be afraid of calling your doctor with questions - pregnancy is special - and this is your first time. Ask for recommended dietary ideas. Best wishes!