Smoking marijuana, having a mother with diabetes or being short could increase the risk of first time mothers having a premature baby, an Australasian study has found.
More than 3000 pregnant women in Auckland and Adelaide took part in the Screening of Pregnancy Endpoints study to identify the most common risks for babies being born early.
More women are giving birth to babies before they are due at 40 weeks, researchers said in a paper published in the Plos One today.
The earlier a baby is born, the higher the risk of medical and social disabilities.
Six per cent of New Zealand babies are born between 32 and 36 weeks gestation, a Health Ministry report, released last month, says.
Babies born before 32 weeks' have a low risk of survival.
Of the 3184 healthy New Zealand and Australian women who took part in the study between 2004 and 2008, 312 had premature births.
Different risk factors were found for different complications:
For women who had a premature birth with intact membranes the risks included shorter cervical length, use of marijuana pre-pregnancy, being Caucasian, having a mother with diabetes and a family history of babies born with low weights.
For women who had a premature birth after pre-labour rupture of the membranes the risks included shorter cervical length, being short in height, longer time to conceive, not waking up at night, maternal history of miscarriage and family history of recurrent gestational diabetes. However, researchers said it was difficult to predict whether a first-time mother would have a premature baby even after identifying all these risks.
''The ability to predict pre-term birth in healthy nulliparous women using clinical characteristics is modest.''
Doctors deem previous premature births, multiple pregnancy or cervical surgery as ''major risk factors'' for expectant mothers going into labour before 40 weeks.
Researchers hoped the study would lead to the development of screening tests to predict premature births, small babies and preeclampsia, which is the rapid rise in blood pressure that can be fatal to both mother and baby.
- © Fairfax NZ News
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