Miscarriages

My husband and I have lost 2 pregnancies this year. One in March and I lost a huge amount of blood and the other one in July. We are currently TTC. I'm afraid that it will WMD up in another miscarriage and he wants another baby really bad. I have had two healthy kids so I don't know what's the problem. And sadly the doctors haven't given me a solid reason,just said they where spontaneous😠😒. I take prenantal vitiams every day..can anyone give me some good advice on what I can do to have a healthy pregnancy?