[kaitai]

Yes, I wondered about this as well. I understand why the author might not have observed women sleeping, and certainly wouldn't have photos, but one might at least mention it (especially given all the attention to the penis). Bust size & placement for sure has a significant effect on where arms can be placed, among other things.

It seems that the author's observations are primarily from various camping-equivalents, more so than home life.

To my sibling commenter, whether pregnancy is or isn't "healthy" isn't quite the point, IMO. Various stages of pregnancy do occupy a non-trivial part of many people's lifespan and significantly change the ergonomics of sleep. Given that humans have been getting pregnant for a long time, it is a big miss to not even mention that it hasn't been considered. Academic training tries to impress on most authors that they should mention what they're ignoring and why, not least to set up the citation train for the future and support grant applications.