Pregnant women are being reminded to heed dietary guidelines because not doing so can result in the death of unborn children.
Such deaths are fairly uncommon, but there have been at least nine recorded in the past four years.
Last year, five women between 23 and 36 weeks pregnant were struck down with listeriosis, and three of their babies died. From 2010 to 2012 there were 12 cases of perinatal listeriosis, with six baby deaths.
Listeria is one of several food-borne illnesses, including toxoplasma, methylmercury and salmonella, which can cause severe complications in pregnancy, when the immune system is lowered.
The Ministry for Primary Industries principal health advisor, Dr Craig Thornley, said while such cases were rare, it was important pregnant women followed food safety recommendations to avoid any risk.
"It's not common but because each case can be fairly severe and could have really tragic outcomes, this is probably one of the major reasons we have these recommendations."
He said listeria was one of the key drivers behind the guidelines, which are revised and updated every few years.
Listeria bacteria can be found in refrigerated, ready-to-eat foods such as meat, poultry and seafood, or food made with unpasteurised milk.
It can cause miscarriage, lead to premature labour and infant death, or babies can develop health problems such as paralysis, seizures, blindness, or brain and heart impairment.
Dr Thornley said a few simple dietary changes could substantially reduce the chance of infection.
Avoiding raw milk and eggs, unpasteurised cheese, processed and undercooked meats, some seafood, and even sushi and hummus would cut down the chance of becoming ill.
New Zealand College of Midwives midwifery advisor Lesley Dixon said women should focus on what they can eat.
"I think we get hooked up on 'we can't eat this and we can't eat that' and what we forget is what we can eat and what we should be eating," she said. "Yes we can't eat brie and camembert anymore but actually we can still eat cheese."
Advice shocks 15 years on
When Amanda Ashman was pregnant with her son Jake in 1997 she wasn't warned not to eat certain foods.
Amanda Ashman with son Jacob and daughter Mackenzie Wyngaard, who has three food allergies. Photo / Greg Bowker
So when she fell pregnant again in 2012 with her daughter Mackenzie, the barrage of food safety advice came as a big shock.
"I was constantly saying 'I was never told any of this when I was pregnant with Jake'."
The 34-year-old West Auckland mum said as a pregnant 17-year-old she knew not to drink or smoke but doesn't recall anyone advising her not to eat food that could cause her to become ill such as unpasteurised cheese, pre-cooked ham, and raw eggs.
She ate whatever she wanted and did not have any problems.
She said it was concerning to find out later pregnant women were warned off some food.
"I thought it was strange that I wasn't warned about it when I was carrying Jake."
Fifteen years later, when pregnant with Mackenzie, it was a different story.
She was made aware of the guidelines by her midwife and kept to them but thinks they might be a bit over the top.
"I think maybe it's a little bit exaggerated. I didn't change anything with Jake and he's fine."
Ironically Jake, now 16, is a healthy high school student but Mackenzie, 18 months, has three severe food allergies.
"She's allergic to dairy, eggs and nuts - quite bad. It makes you wonder."
Off the menu
*Raw milk (any unpasteurised milk)
*Soft cheese (unless pasteurised and eaten immediately after opening)
*Raw and undercooked eggs (in eggnog, smoothies and home-made mayonnaise)
*Oysters and Queen scallops
*Raw or smoked fish and seafood
*Processed meats (such as ham, salami, luncheon and pate)
Source: Ministry of Primary Industries