Senator Nick Xenophon has put the brake on the government’s plan to stop “double dipping” in maternity leave, with legislation to stop mothers claiming both government-funded leave and their own workplace schemes likely to fail without the three votes he controls. Xenophon told the press yesterday that it was “manifestly unfair” for the law to come into effect on January 1, 2017, when families already expecting babies had made plans based on the laws as they currently stand.

“I do believe, and I’ve discussed this with my colleagues, that having any such scheme as proposed by the government to start on January 1 would be manifestly unfair for any woman that is pregnant.”

“To apply for somebody who is already pregnant, who in good faith thought they would get the benefit of that, that’s a big issue.”

Xenophon said he would be open to discussing other start dates, and that a period longer than nine months could be on the table. The Huffington Post is reporting that women due right at the start of January have been researching ways to bring labour forward in order to be eligible under the current arrangements. Before dismissing the idea as ridiculous, it pays to look at the last time the Australian government offered money to new parents — John Howard and Peter Costello’s baby bonus. Research by Andrew Leigh (yes, the Labor MP) and Joshua Gans showed that in 2004 births dropped significantly the week before the baby bonus came into effect, while there were more babies born on July 1, the first day when babies came with a $3000 bonus, than in the 30 years previously. The bonus was announced seven weeks before it was due to come into effect, meaning the bonus hadn’t affected the decision to become pregnant in the first place, but it could be shown to effect existing pregnancies. The pattern was repeated when the bonus was increased in 2006. So even if the “double dipping” changes are delayed in time for buns already in the oven, it’s likely that some will be a little underdone when they are welcomed to the world.