Imogen was a child bride.

I've been thinking this ever since Woe was described as half the height of a normal woman. That felt child bride coded, but here is the rest:

Kier didn't have his first child until he was 44. If Kier met his wife in his youth, as Lumon would have you believe, she wouldn't be in good shape to have two children one year apart from each other in her 40s in 1885 and 1886 respectively.

All the evidence provided in attached pictures supports the idea that he found himself a child bride at the ether factory, while undercover as a swabman.

I included some more fantastical pulls about Woe because I believe Imogen is represented as the woeful bride. Kier seems to have felt some kind of way about the sins of his past on his deathbed, so he made up the fourth appendix and Dieter to sever himself from the sin. He made up Dieter to be his scapegoat. (If you grew up not religious, like I did, google scapegoat+religious) Part of his guilt (?) might revolve around his child bride, given she may have been sick from the factory and she was definitely woeful.

The fact we only know two things about Imogen, she was a swab girl and married Kier, leaves a lot of question marks about her ultimate fate. Poor girl.