Work Guilt

I dont know if anyone else experiences guilt for taking time off work. I have an extremely stressful job. The last few months have been particularly difficult with constant pressure to perform at work. Whilst my manager has been super understanding and supportive, the rest of the organisation hasnt been, and the expectations are as long as I am at work I need to perform at 150%. Often I am asked to pick up more work. My pregnancy has been ok so far but as the pregnancy progresses I can feel myself slowing down. Last week I hit rock bottom, experienced some bleeding. I went for a check up, and baby seems ok, but dr said I should "take it easy". Ive asked to be booked off for a couple of days and my dr gave me a letter. I am 27 weeks now and I just feel so guilty for taking time, as they are already so short staffed and now without me there it means my colleagues have to pickup my work load.