Are you a lawyer? I find that law is particularly unsympathetic to illness or any weakness, and you get a lot of war stories about going into labour at work, or returning the next day etc.
Can you negotiate part time? I am working up to 39+3 this time (3 work days left!), but only work 3 days a week (I have another child), and I have found that it is helped to have a couple of days of being at home during the week has allowed me to recover for my work days. It might be a compromise to finishing up early.