Free vaccinations will be offered to pregnant Canterbury women and mothers of newborn babies as the region tackles a whooping cough epidemic.
The vaccinations will be offered to women who are more than 30 weeks pregnant and mothers up to two weeks after the birth of their child.
The vaccine is generally available to children from six weeks of age to 11.
Canterbury Medical Officer of Health Ramon Pink says the region's current whooping cough epidemic warrants the health board expanding the availability of the vaccine.
Dr Pink says there have been 515 cases of confirmed or probable whooping cough in Canterbury since August 2011 and 15 babies aged under one year old have had to be hospitalised.
Babies are most vulnerable to severe outcomes from contracting the illness, he says.