The number of teenage mothers has jumped after decades of steady decline and NSW has had the most significant increase.
The teen fertility rate in NSW rose 15 per cent from 2007 to 2008, according to the Australian Bureau of Statistics.
Nationally, the number of teenagers giving birth rose 10 per cent, from 11,204 to 12,326.
While the increase concerns some health professionals, others say it is in line with the overall baby boom.
&amp;lt;iframe id="dcAd-1-4" src="http://ad-apac.doubleclick.net/N6411/adi/onl.smh.lands/lands/life;cat1=life;ctype=article;cat=lands;pos=3;sz=300x250;tile=4;ord=9.0107024E7?" width='300' height='250' scrolling="no" marginheight="0" marginwidth="0" allowtransparency="true" frameborder="0"&amp;gt; &amp;lt;/iframe&amp;gt;
Dr Patricia Weerakoon, co-ordinator of the University of Sydney's graduate program in sexual health, said teenagers were becoming sexually active earlier and putting themselves at risk of sexually transmissible illnesses and unplanned pregnancies.
''The rates of sexually transmissible infections in young people are rising because they are having unprotected sex. That is also reflected in the rising number of teenagers having babies.''
While young people are reaching puberty earlier, their brains do not fully develop until they are in their late teens or early 20s.
''Their hormones are saying they are ready to become sexually active but their brains won't fully mature for another few years,'' Dr Weerakoon said. ''Young teenagers do not have a well-developed control mechanism which is why they engage in risky behaviour. They don't think about the long-term consequences of their behaviour.
''They go for instant gratification first and don't worry too much about the long-term consequences of having an unplanned pregnancy.''
Australia's teenage fertility rate of 17 births per 1000 teens is lower than the rate in the US (51 per 1000), Britain (27 per 1000) and New Zealand (26 per 1000).
But it is higher than many countries including Germany (10 per 1000), France (eight per 1000) and the Netherlands (four per 1000).
Associate Professor Juliet Richters, of the University of NSW school of public health and community medicine, said teenagers, particularly those from lower socio-economic backgrounds, needed more information about sexual health.
''Australia is only doing medium well in terms of providing support and sex education to young women,'' she said.
''We are not doing as well as the Netherlands or Scandinavia in terms of helping teenagers manage sex and fertility.''
She was not alarmed by women in their late teens having babies but said mothers in their early teens were a cause for concern. ''Young women in the 14, 15, 16-year-old age group who become pregnant tend to be at risk … A lot of them don't necessarily want to have the baby.''
Medicare data suggests half of all teenagers who conceive do not proceed with the pregnancy. Up to 60 per cent of those who give birth do not have a male partner at the time.
NSW Health data shows that teenage pregnancies are clustered in rural and lower socio-economic areas of Sydney.
The Greater Western Area Health Service has the highest rate of teenage mothers, recording 8.1 per cent of NSW births, followed by the Hunter and New England area and the North Coast (both with 6.7 per cent), the Greater Southern area (6.6 per cent), Sydney West (3.8 per cent), Sydney South West (3.1 per cent), South Eastern Sydney and Illawarra (2 per cent) and North Sydney and Central Coast (1.8 per cent).
Suggestions the federal government's $5000 baby bonus may have been encouraging teenagers to have babies prompted the lump sum payment to be changed to instalments for mothers aged under 18.
Professor Anthony Smith, from the Australian research centre in sex, health and society at La Trobe University, said supporting teenage mothers was important, particularly when it came to helping them complete their education.
''Programs for young mothers in schools have been running for about 15 years now,'' he said. ''Before, if a young woman became pregnant while at school that was the end of her education full stop.
''But over the past decade or so people have moved towards lifelong learning and a recognition that for many women there will be an interruption to that process through child-bearing whether it happens earlier in life or later in life.''
The NSW Education Department has made the successful young mothers program implemented at Plumpton High School in western Sydney available to all high schools.
However, most women under 20 who have babies are in their late teens and the pregnancies may be planned as part of a committed relationship, Professor Smith said.
''One of the problems is as soon as you mention teen pregnancy everyone thinks of a 14-year-old when in fact most of the teen pregnancies … occur in the 18, 19-year age bracket.''
Via Peter Kyriakoudes