A while back I read the book Caroline: Little House, Revisited by Sara Miller. It's a book which attempts to imagine what life might have looked like for Laura Ingalls Wilder's mother during the events of "Little House on the Prairie".
For the majority of the book, Caroline is pregnant, and throughout the story she continually expresses shame/embarrassment whenever she's someplace people outside the immediate family might see or take notice of her "condition".
My question is, is the book accurate in that it would have been seen as somehow "improper" for a pregnant woman to appear in public or seen by a man, even in her husband's presence?
No - this is a long-standing stereotype, probably influenced by the general nineteenth century unwillingness to speak openly about pregnancy, the word "confinement" as a euphemism for labor (which has made later generations think that pregnant women were confined to their bedrooms), and of course the depiction of Scarlett's pregnancy in Gone With the Wind. There is always more to be said, but there is much more discussion in my answer to During the time of corsets and tight waisted dresses for women what would they wear during pregnancy?