NHS figures have revealed just one in three pregnant women in Crawley have had the flu jab.
More than 1,000 expectant mothers registered in the town did not get immunised for this year’s flu season.
Doctors and midwives urged the women to have the free jab.
Dr Nick Nedall, screening and immunisation manager for NHS England (Surrey and Sussex) said: “Complications are reduced by having a simple vaccination, and I would urge all pregnant ladies to contact their local GP surgery and make an appointment as soon as possible.
“It’s important to recognise that significant risks exist to both mother and unborn child, should they contract the flu virus.”
Studies have shown the jab is safe and immunises newborns against the flu for a few months.
Vikki Turner, 19, a cabin crew member from Ifield, said she believed getting the jab was the ‘right thing to do’.
Vikki was vaccinated at her first doctor’s appointment after getting pregnant.
She said: “You don’t want to get ill at all during your pregnancy.
“I thought it was the right thing to do because at the end of the day it helps me protect my baby from things that would potentially cause it harm.”
She added: “There’s a lot of speculation and theories that jabs can cause things to go wrong in the pregnancy. I think that’s why a lot of mums-to-be are cautious about getting them.
“I don’t think there’s a big risk because if something was wrong with it they wouldn’t offer it and they would have found out.”
Evidence shows pregnant women have an increased risk of serious complications if they get flu. The flu jab reduces the chances of a miscarriage, low birth weight and premature birth. Pregnant women unsure about the jab are advised to contact their GP or midwife.