More babies are being born than ever before, the percentage of mothers aged in their teens continues to fall, and the number of women giving birth over 40 is on the rise, according to the latest Australian Institute of Health and Welfare figures.
The institute's annual Australia's Mothers and Babies Report, released today, reveals that a total of 301,810 babies were born across the country in 2011, representing an 18.3 per cent increase on the number of births in 2002.
Of the babies born in 2011, 3.7 per cent were born to mothers aged under 20, compared with the 4.9 per cent born to teens in 2002. Mothers aged over 40 represented 4.3 per cent of all births in 2011, compared with 3.0 per cent in 2002.
There were 650 women, or 0.2 per cent of all mothers, who were aged over 45 when they gave birth in 2011. The proportion of mothers aged 35 and over increased from 18.1 per cent in 2002 to 22.5 per cent in 2011.
AIHW Spokeswoman Elizabeth Sullivan said maternal age was an important factor in determining risks in pregnancy, with both the oldest and youngest mothers at the most risk of negative pregnancy outcomes. In particular, teenage mothers were most likely to have smoked during their pregnancy, she said
"Of all teenage mothers, almost 36 per cent reported smoking during pregnancy, compared with 13 per cent of all mothers," Professor Sullivan said. "Teenage mothers also have higher proportions of low birth weight babies compared with women in other age groups, and the highest fetal, neonatal and perinatal death rates."
Women aged over 40, meanwhile, were more likely to give birth via caesarean section.
"Caesarean section rates increased with advancing maternal age," Professor Sullivan said. "In 2011, caesarean section rates ranged from 18 per cent for teenage mothers to 49 per cent for mothers aged 40 and over."
The average age of all mothers giving birth in 2011 was 30 years, representing a 7.5 per cent increase in maternal age since 1991. Meanwhile, the average age of women having their first baby has increased steadily from 27.6 years in 2002 to 28.3 years in 2011.
The incidence of multiples has also increased over the past two decades. That rise is being attributed partly to the increasing age at which mothers are giving birth and also to the use of fertility treatments. In 2011, there were 4595 multiple pregnancies across the country, consisting of 4520 twin pregnancies and 75 triplet and other higher-order multiple pregnancies.
The report also reveals the continuing trend for new mothers and babies to spend less time in hospital after birth. From 2002 to 2011, the proportion of hospital-born babies being discharged less than five days after birth increased from 67.4 per cent to 78.6 per cent. Of those babies, 2.9 per cent left hospital less than 24 hours after being born, 13.2 per cent stayed for one day and 22 per cent left hospital two days after birth.
Meanwhile, the proportion of babies with a length of stay in hospital of five days or more decreased from 32.6 per cent in 2002 to 21.4 in 2011.
In 2011, 8.3 per cent of babies were born premature - that is, before 37 completed weeks of gestation - and 0.7 per cent were
post-term, or at 42 weeks gestation or more.
Sadly, the rate of stillbirth remained steady at 7.4 deaths per 1000 births.