Is it safe to take vit c 500-1g( recurrent urti), vit d 1000u( low level) & vit b comp( tiredness) on top of pregnancy suppl daily in 1st trimester?

Yes: I can't promise these will do you any good. Good luck with your pregnancy!

Yes, totally safe: I advise at least 500 mg of vit c 2x/day for everyone. Most adults need 4000-5000 units of vit d to achieve optimal levels unless they get a good dose of midday sun from april-sept. B vitamins are safe and might help energy. Many women may also benefit from additional magnesium (as taurate, glycinate or citrate) during pregnancy.