“Early last year, Google announced it would be increasing parental leave for full-time employees to 18 weeks for all parents and 24 weeks for birth parents”

Perhaps they’re widening it to include people giving birth. Some people giving birth may then give up their child for adoption, so they wouldn’t want to be called mothers. Either that or they’re trans in some way but able to give birth.

I think the point being is that there are many ways a family is constructed, and many situations people find themselves in.

It’s being used wrong in the instant article by a clumsy writer triyng to condense the phrase “parents who give birth” used in the referenced earlier article on the leave policy.