What causes acne ? only 2weeks pregnenent and acne is showing on my face ?is being pregnant a cause?

Yes, sebum increases: Hormones, especially progesterone, stimulate the production of sebum and causes it to block the hair follicle causing acne. Progesterone levels are higher after ovulation and remain elevated during oregnancy, so yes, it common to have increased acne during pregnancy. Also, birth control, like the Depo-Provera shot, which is a progestin medication.