I've always hated the term "we're pregnant." It has really creepy undertones and makes me dry heave a little. So much so, in fact, that my husband used to say it as a joke because he knew how much I hated it. It's not just that it feels like a clumsy attempt at solidarity that ends up sounding insincere and patronizing, it's also because there are some really compelling reasons why saying "we're" pregnant is sexist.
When I had just given birth to my son, I had to share a mother and baby room with a couple I didn't find particularly charming. They had a slew of visitors at all hours of the night, and were just all-around inconsiderate. So, when I heard the new father telling a nurse "we had an episiotomy" I lost it. He was not trying to support his wife with this gross statement, he was trying to elicit some sympathy for a procedure on a body part he doesn't even own. Yeah, I wasn't a fan.
A uterus is not shared. A man can be fully invested and supportive of a pregnancy without trying to take ownership of the experience. The baby has been jointly created and both mom and dad have full parental rights to the child, but the pregnancy itself is very much a solo venture and any attempt to claim "we're pregnant" is, in my opinion, totally sexist for (at least) the following reasons: