Information from the centre for Disease Control (CDC) in USA about Whooping Cough (Pertussis) Vaccination in Pregnancy:
You can start protecting your baby before birth
Information from NT Department of Health:
Pertussis Vaccination in Pregnancy
NB. More recent advice suggests that this vaccine can be given at any time after 20 weeks gestation (but ideally at least two weeks before birth, so before 32 weeks gestation is preferable).