Kissing a friend's new baby might seem like a natural, and harmless, thing to do when you meet the infant for the first time.
But a social media campaign is now urging visitors to refrain from kissing babies following a number of high profile cases resulting in serious illnesses and deaths.
The hashtag #dontkissthebabies is gaining momentum here and overseas to warn parents about the dangers everyday illnesses pose to newborns.
People are being urged to stay away from babies if they are unwell, refrain from kissing newborns and wash their hands before handling a new arrival.
Brianna Nichols of Illinois in the US posted a Facebook post including a photo with the hashtag last year, which has since been shared 482,000 times.
In the post, she urges: "Please don't kiss the babies! And people with little babies, please make your guests wash their hands and make sure they are healthy."
Ms Nichols also warned about the dangers of RSV (Respiratory Syncytial Virus), a common respiratory infection that can be deadly to babies. In Australia it peaks around the winter months and early spring.
"We all love that people love our babies, but if you have even a cold, please don't get in their face! In adults, RSV seems like just a cold but can have a baby fighting to breathe. If you have a cold, you could have RSV and not know it," she wrote.
Earlier this year, Ashley Conklin of Missouri in the US uploaded a Facebook post with a video of her newborn son Oliver struggling to breathe and wrote, "in case you need a reminder of why you should stay away from newborns, even with a sniffle. My heart is broken".
The six-second video has been viewed more than 1 million times and was accompanied by a Facebook post that she asked people to share.
"Everyone needs to see what a simple cold can do to babies. My 11-day-old (now 13 days old) has contracted RSV, pneumonia, and bronchitis due to a simple viral cold. Stay away from newborns if you even think you're getting sick!" she said in the post.
NSW Health says RSV is a relatively common infectious disease that can cause bronchiolitis in young children and can be very serious in babies under six months, sometimes resulting in hospital treatment.
It says RSV can be spread through droplets from a sneeze or cough. A person can become ill after touching their nose or eyes if they have been in contact with a person with RSV or a contaminated item. People can remain infectious for up to 10 days.
Luckily, Oliver survived, but others have not been so lucky.
US dad Jeff Gober began raising awareness about the threats that common viruses and germs pose to newborns after his only child Mallory died of complications from the common Herpes Simplex virus earlier this year.
In a Facebook post, which has been shared 283,000 times, Mr Gober wrote: "I've been pretty silent since Mallory's death. It's taken me over a month now to write this, but if any good can come from her passing and prevent someone else from experiencing the heartache, then I would be remiss not to try.
"If you have a new baby, or will be around a new baby, wash your hands. A lot.
If anyone wants to hold your baby, make sure they wash their hands first. Then make them do it again."
Mr Gober explained that HSV-1, known as the cold sore virus, is extremely common, carried by more than 60 per cent of the world's population, but many people never show symptoms and don't know they have it.
"For newborns, it is more than likely fatal, as was the case for Mallory," he says, adding she was never in contact with a person with an active cold sore and was never kissed on the mouth by a visitor.
"In spite of that, she caught HSV-1 within her first week of life and we had to watch her die slowly for nearly two weeks.
"Mallory could not keep her hands out of her mouth and eyes and she was constantly sucking on her fingers, so it's almost certain that the virus got onto her hands at some point.
"She had no symptoms beyond a high fever for most of the first week, and by the time blisters showed up it was probably too late for the antivirals to be effective.
"Please, if you're reading this, be extra diligent about washing your hands around newborns. Statistically speaking, you're probably infected with HSV-1 whether you know it or not."
According to NSW Health, children are at increased risk of catching infectious diseases because their immune system has not yet developed properly. Sick and premature babies are at added risk.
The Going Home booklet handed out to parents whose children have been treated in the Grace Centre for newborn care at Westmead Children's Hospital says babies' immune systems develop gradually over months and parents should take steps to avoid the risk of infection.
The booklet recommends parents limit contact with visitors to the home in the first few weeks after leaving hospital and ensure all visitors wash their hands thoroughly with warm water and soap before touching the baby.
It also recommends parents avoid taking babies to crowded public places, especially those with air-conditioning, such as shopping centres, and reduce contact with anyone who has a cold or fever.