What Are the Benefits of Longer Maternity Leave?

Not much, according to a new working paper by Astrid Würtz, a Danish economist.

In 1984, Denmark increased the amount of time parents could take off after the birth of newborns by 50 percent from 14 to 20 weeks. Würtz exploited this change to find out what happened to the 8,600 childern born within two months of when the new law went into effect.

She found no difference between the two groups of children when measuring their reading scores at age 15, high school enrollment levels, or high school GPAs at the age of 21.

Another study along these lines by Michael Baker of the University of Toronto and Kevin Milligan of the University of British Columbia found that after maternity leave was extended in Canada, mothers spent more time breastfeeding their children. However, Baker and Milligan didn't find any improvements in childrens' health levels as a result of the change.

Of course, this doesn't necessarily mean that extended parental leave doesn't do any good for children.

First, increased use of day care services in Denmark might have offset any negative repercussions associated with "only" 14 weeks of leave, says Würtz.

Second, Würtz looked at long-term effects of the new Danish law. It's very possible that benefits existed, but were only noticeable in the short-term.

And third, gains could show up in softer attributes, or, perhaps, more than 20 weeks of leave are needed to see any of the possible advantages of longer parental leave.