Public Service Association national secretary Glen Barclay said a rise in the use of casual and fixed-term contracts meant fewer workers were eligible for paid parental leave and while it was an excellent concept, the current rules made it increasingly inaccessible to people who should benefit from it.
The amount of money available on paid parental leave - a maximum of $504.10 a week before tax - also meant a significant drop in wages for most full-time workers, he said.
Rebecca Matthews, convener of the 26 for Babies coalition, which supports 26 weeks of parental leave, said the main reason women returned to work early was that they could not afford to stay off.
The IRD figures show that, of those who took paid leave, 94.4 per cent took the full 14 weeks. The figure was the lowest uptake in the past seven years but only slightly down from 95.2 per cent in the previous year.
According to separate government figures, only 40 per cent of new parents are receiving paid parental leave.
National Council of Women president Barbara Arnold felt financial pressures or the restrictions on who was eligible could be preventing the other 60 per cent of new parents taking the paid leave.
"Parents know this time is critical, but they sometimes have to make these hard decisions about how they actually survive to get enough food and electricity and pay the rent."
National's spokesman on labour, Simon Bridges, said he wanted to broaden the eligibility for paid parental leave to address more modern working arrangements and diverse family structures. Consultation on his discussion document closed last month and more than 900 submissions were being analysed.
"We've always said that when we could afford more, we would look to extend paid parental leave and that's exactly what we're doing. Overall, our changes will make parental leave available to more people, for a longer period and with more flexibility."
The Government announced this year that paid parental leave would increase to 16 weeks from April 1, 2015, and to 18 weeks the next year.
Labour's spokeswoman for social development, Sue Moroney, said: "The number of people in the paid workforce is growing and participation for women is growing - you should see that [parental leave] number increasing."
Mother tells of guilt over work return
Alma Shaw felt like an "awful mother" when she returned to work when her younger daughter was three weeks old - but for her, it was the only way she could keep a roof over her family and put food on the table.
The 29-year-old Wellington mother of two went on leave just three days before Ivy was born and returned 15 days later. She said financial restraints were the only reason she was not able to take longer off with her daughter, as with the maximum weekly pay - $448 at the time - from the Inland Revenue Department she would struggle to cover $330 a week in rent plus other expenses such as power and food.
Instead of applying for paid parental leave, she took the $150 in tax credits available from the IRD for eight weeks after the baby's birth and returned to her job as a policy adviser.
"I was questioning my ability to be a parent because I had to go back to work in order for my family to be able to survive ... It was horrible."
