
As it's licencedbfor use daily in last three weeks of pregnancy, to three days post whelping, so perfectly OK.
I assume you did not use it in the last weeks of pregnancy, as the bitch would have been worm free and pups would not have had them passed on ( or less than 2%).
So you need to give Mum 1ml per kilo body weight as one dose. SO 20ml for a 20kg bitch.
You will drfinately need to worm the pups at two weeks. 1/2ml per kg of their weight every day for 3 days.