Ang Tdap vaccine ay common lang na binibigay especially pag pregnant kaya don't worry! From what I've seen sa friends ko, usually mild lang yung side effects, like soreness sa injection site, slight fever, or tipong flu-like feeling for a day or two, pero mabilis mawawala. Best talaga na i-confirm mo yung specifics with your OB or doctor kasi bawat tao may different reaction, pero overall safe siya at super importante lalo na pag may baby ka na soon!