Is D And C Safe To Do During Menstruation?

I am 30 years old. I usually have my period for four to five weeks at a time. I have had a pap and ultrasound. I am on birth control. My doctor would like me to have a D and C. I am overweight, anemic, have asthma and high blood pressure. Can I have the procedure, if I have my period? I have never had surgery and am very scared.