Re: Why do miscarriages happen? Is there anything I can do to avoid it? How do I know if I'm at risk?
Unfortunately, there really is no way to prevent a first trimester miscarriage, and it is the most frustrating thing about obstetrics. But, after ultrasound confirms your baby’s heartbeat at eight weeks, the risk of miscarriage is only about 3%. The risk falls even lower (1%) after a normal ultrasound at 16 weeks. (Overall, from conception, about 10 to 15% of pregnancies end in miscarriage.) Most pregnancy losses are diagnosed in the first trimester when a patient experiences bleeding or cramping. Many women may have no symptoms that the pregnancy has stopped progressing until a routine ultrasound examination indicates no heartbeat.
Most miscarriages are caused by chromosomal abnormalities in the pregnancy resulting from an error during fertilization. Unfortunately, there is nothing you can do to avoid this. If you have experienced a single miscarriage, you are not at increased risk for miscarriage in a subsequent pregnancy. However, if you have experienced two or more consecutive miscarriages in the first trimester or one second trimester miscarriage, you are at higher risk for a miscarriage in the next pregnancy and should be evaluated for an underlying cause. Certain blood clotting disorders (otherwise known as thrombophilias), thyroid disease, lupus, or diabetes can increase your risk of having a miscarriage. An abnormality in the way your uterus has formed can also be associated with recurrent pregnancy loss, particularly after the first trimester. If you are concerned that you may be at high risk for recurrent miscarriages, you should discuss your concerns with your obstetrician.