Miscarriages are the the most common complication of pregnancy, affecting 15% of pregnancies. Two thirds of this 15% are undiagnosed and unrecognized. Studies found a plethora of different associations, placental biology, asthma depression, and irritable bowel movements, smoking, mental health, general well-being. Miscarriage can lead to depression and cardiovascular disease. This was a large study involving genetic info from 420,000 women.