"The placenta may struggle to maintain oxygen and blood flow to the baby during labour. These issues can result in life-long issues in a baby [such as] being neurologically damaged at birth, and having significant behavioural and learning problems.
"It also results in reduced ability to breastfeed and an increased number of children being hospitalised for bronchiolitis and other breathing difficulties.
"The figure was higher for Maori women where 39 per cent were smokers compared with 12 per cent for non-Maori."
New Zealand College of Midwives regional chairwoman Juliette Robinson said she wasn't seeing pregnant smokers in her own practice, but said many midwives would.
"It's a funny thing with smoking though, people seem to compartmentalise that as something they don't have to deal with - it's very difficult to quit smoking and nicotine receptors are increased when you are pregnant, which makes it harder to quit."
She said that some pregnant women were still drinking while they were pregnant.
"There's still quite a bit of alcohol use in pregnancy, and a misunderstanding about what they should or shouldn't have or can and can't have. A lot of it is hidden at home because it is socially unacceptable."
Rotorua midwife Lisa Pue said women were more likely to admit and seek support for a smoking addiction than alcoholism. She said smoking often went hand in hand with drinking, the effects of which were long-lasting.
"Family violence, abuse, drunk-driving - the whole lot.
"That is something I think we really need to run a campaign on and advertise more because with smoking we can do referrals for Smoke Free or Quitline, with alcohol they've got to go to Alcoholics Anonymous. I think it's an addiction and for any addiction it is hard to do that."
She said it was important for mothers to remain smoke-free once they had given birth.
Health during pregnancy
* The pregnancy and first three years of life are the most important years of life - they determine the rest of a child's life.
* Pregnant mothers need to eat well, not take drugs, alcohol or smoke cigarettes. They also enough rest and need to exercise in moderation.
* Alcohol causes lifelong damage to newborn brains, causing fetal alcohol syndrome, serious intellectual and learning problems.
* Drugs also damage a baby's brain and can lead to major behavioural problems
