For modern mums, new lives begin at 40 Twice as many women took maternity leave at the age of 41 than at 21. CAREER women have made mid-life motherhood the norm in Australia, as more babies are now born to the over-35s than the under-25s. Today's women are twice as likely as their mothers were to have a baby in their late 30s or 40s and the proportion of older mums has doubled in two decades. And data shows that working mothers in their 30s and 40s account for two-thirds of the 255,000 women granted taxpayer-funded parental leave since its introduction two years ago. Just a third of the women on paid government maternity leave, which is only given to those with a job, are in their teens or 20s. And six per cent are in their 40s. Social researchers blame the mid-life "baby-bump" on job insecurity, health problems and a shortage of men who feel ready for fatherhood. "There's a misconception that women who don't have children put their career first, are selfish and have chosen to do that," Monash University researcher Sara Holton said. But for many women, they don't have the choice, because circumstances prevented them from having children earlier. The latest Australian Bureau of Statistics data, based on births in 2011, shows the proportion of new mothers aged 35 or older has doubled in two decades. In 2011, almost one in four was 35 or older. But in 1993, just 12 per cent of new mothers were 35-plus, according to the earliest comparable ABS statistics available. Only 18 per cent of today's babies are born to mothers younger than 25, compared to 25 per cent 20 years ago. Nearly one in five of the nation's babies in 2011 was born to a mother in her 30s. Another 4.2 per cent were born to 40-something mothers, and women in their 50s had 53 babies. In 1993, a mere 1.6 per cent of babies were born to mothers in their 40s, and only two women in their 50s had babies. Dr Holton said her team's study of more than 500 Australian women found that money was not the main reason for postponing parenthood. "A lot of women said the reason they hadn't had a child was that their partner was just not interested in having children," she said. Women aged 30 to 35 are aware their clock is ticking and want to have children. A lot of them had to make decisions about whether to continue with the relationship and hope their partner changed their mind, or to find someone else. Dr Holton said women also wanted to secure a flexible but not necessarily highly-paid job before they had a baby. "In our study, women wanted flexibility, not to be the next CEO of the company," she said. Professor Karen Thorpe, research director of the University of Queensland's school of psychology, said contraception and the availability of screening for genetic disorders had encouraged women to wait to have kids. "The majority of these births are through choice and not by mistake, so these babies are planned and celebrated," she said.