Pregnant teenagers are smoking in the hope of having smaller newborns, new research has found.

A 10-year national anthropological study into smoking in Australia has revealed girls as young as 16 are taking up the killer habit in an attempt to reduce the birth weight of their unborn babies.

Shockingly, expectant teens are more fearful of labour and having a large child rather than the health complications caused by cigarettes including higher stillbirth rates and increased risk of childhood asthma and allergies.

In research led by Dr Harvey Ho, of the Auckland Bioengineering Institute at Auckland University, the aim is to produce a computer programme that can be used midwives and other health workers to warn women against smoking during pregnancy, by showing them video simulations that demonstrate the risks to the fetus.

Associate Professor Simone Dennis, of the Australian National University, said she was stunned to discover pregnant teenage girls smoking during the course of her research.


"They had read on packets that smoking can reduce the birth weight of your baby, which is obviously not how the public health message is intended to be taken," she said.

"They were scared because they were small. The worst thing that could happen to them was to have an enormous baby.

"Some were young, 16 or 17 years, and their overriding fear was 'Oh my God, I'm going to have an enormous child', so they were actively using cigarettes to medicate against that.

"Some had even taken it up for the first time for that very reason, and some smoked harder, hoping the promise on the packet would come true. If you smoked more, you could make it better. I was really struck by that."

About 18 per cent of pregnant women still smoke in Australia, and studies show smoking mums are twice as likely as nonsmokers to have low birth weight babies, about 200g lighter.

Previous studies have found almost 37 per cent of mothers under 25 years of age smoked cigarettes in their pregnancy compared with 10 per cent of those over 30 years.

During her research, conducted in several capital cities around Australia, Assoc Prof Dennis also found smokers were increasingly subjected to random abuse from strangers in public places.

She said smokers had become pariahs over the course of the anti-tobacco legislation, to the point where they were verbally abused for stray wafts of smoke outdoors.


"I witnessed a lot of cases of people being abused for breathing smoke on someone else by accident, or if wind picked up and their smoke travelled."

Assoc Prof Dennis, who has just published her findings in the book Smokefree, initially started her research to uncover views of smokers in the wake of the introduction of health warnings on cigarette packets and smoke-free zones.

She also found smokers taking creative strategies to avoid certain health warnings, with many customers asking shops for a different warning or buying "pretty boxes" to put their smokes in.

"I would see blokes deliberately choose the packet with the pregnancy warnings by saying, 'Fine I'll have that one as it doesn't affect me'," she said.

And blue-eyed people had an aversion to the cigarette packet that featured a blue eye being operated on.