High Risk Pregnancy, Sudden Job Leave, HELP!

I've had a very difficult pregnancy and I have been under a lot of physical stress at my job. I've had 3 days off to rest due to my circumstance, but my doctor is concerned. My husband & I spoke about these things and have decided that it's best I don't work right now. We're blessed for him having such a good job, but I need to leave as soon as possible due to my now "high risk" label. I've written this letter to my HR manager and just need a second opinion. I'm unable to get into their office to speak with them right now :/ Do you guys think this is okay to say? I'll be calling in the morning as well. YES, I understand that 2 weeks is proper but sometimes your health is much more important and having a healthy pregnancy is my top priority.
Thank you for allowing me to have the time to rest and regain control of my health situation. I appreciate your help with these things. With this being said, my husband & I have discussed my temporary absence and have come to the decision that it is best for my health and the remainder of my pregnancy for me to not continue working at this time. We've both agreed that it's best for our family, and my doctor is concerned as well and has placed me under a high risk circumstance with my heart condition. I thoroughly enjoy working with all of you and love the job I do. I've felt very fortunate get to know all of you and am thankful for all that I've learned. It isn't easy for me to leave and I regret having to do it on these terms, but I'm unable to get to the office to speak with you until Monday. I have a set of scrubs to return as well as my key, which I will bring back to you come Monday morning. I apologize for this informal and sudden leave but I appreciate your understanding.