Is it possible to get pragnent during the periods? and is it harmful at any point to have pv sex during the periods?

Usually not, but...: A woman doesn't get pregnant during normal regular periods. However, if she has some spotting and is not on her period, but mistakenly thinks she is on her period, it is possible that she is fertile during the spotting. If she has sex during the latter days of her period, sperm might hang around long enough to create a baby if she has very short cycles, such as 3-week cycles. Consider condoms.