The new policy took effect on Wednesday, according to a message to the fleet. The expanded benefit will better support women in the service and improve recruiting and retention, Mabus said.
"We have incredibly talented women who want to serve, and they also want to be mothers and have the time to fulfill that important role the right way," he said in a statement on Wednesday. "We can do that for them."
He added, "Meaningful maternity leave when it matters most is one of the best ways that we can support the women who serve our county. This flexibility is an investment in our people and our Services, and a safeguard against losing skilled service members."
Under the new rule, the additional time off may be taken immediately after the six weeks of convalescent leave previously authorized, or taken incrementally over the course of the first year after the child's birth. The balance of the leave must be used up within that first year.
There were 71,000 women in the Navy and Marine Corps as of January, of which some 27,000 were married, according to Defense Department data.
The new rule doesn't apply to adoptive parents. Adoption leave, which is also considered non-chargeable, is currently 21 days for both male and female sailors and Marines. Adoption leave does not count against regular leave time.
The new benefit also doesn't apply to paternity leave. Married service members are allowed 10 days of paternity leave under a 2008 law that stresses the word "married," though service officials are considering expanding the benefit for single sailor fathers, Navy Times has reported.
Mabus has said a more diverse force is a stronger force.
"When the women in our Navy and Marine Corps answer the call to serve, they are making the difficult choice to be away from their children – sometimes for prolonged periods of time – so that they can do the demanding jobs that we ask them to do," he said. "With increased maternity leave, we can demonstrate the commitment of the Navy and Marine Corps to the women who are committed to serve."
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