Experts still don't know all the causes of a miscarriage but the most common one during the first trimester is a chromosomal abnormality. That means the egg or sperm cell is damaged, a problem occurred during the meeting of the egg and sperm or the egg didn't implant properly in the uterine lining. "The miscarriage is nature's way of taking care of a life that wasn't viable," says Dweck. Other causes include hormonal problems, infections, the mother's health problems, the age of the mother and maternal trauma.
After a miscarriage, it's common for a patient to think she did something wrong; that the miscarriage was somehow her fault. "I have patients saying, 'I went to my Pilates class or I had sex or I was spotting and didn't go to the doctor right away,'" says Armando E. Hernandez-Rey, M.D., an Ob-Gyn and endocrinologist and infertility specialist at Baptist Health Systems in Miami, Florida. The truth is there's nothing you can do differently (sex or no sex, exercise or put your feet up, swear off caffeine or down a glass of red wine) to prevent a miscarriage when there is a chromosomal abnormality. That may not lessen your loss but it may keep you from blaming yourself.