For women who have multiple miscarriages, the pain of repeated loss is often compounded by another reality. The causes behind miscarriage are complex and often difficult to identify, and even those conditions and associations proposed as causes are poorly understood.
“We can do better than this. We need more research”
But there is good news too. Women with recurrent miscarriages can benefit from comprehensive evaluation, treatment and support programs, such as the Recurrent Pregnancy Loss Program at Stanford. Even among those women whose miscarriages don't have an identifiable cause, more than 80 percent of women who've had two or more miscarriages will ultimately have a successful pregnancy with supportive care.
Stanford Hospital & Clinics medical specialists shared this information at a recent community seminar, "Prevailing Over Recurrent Pregnancy Loss," presented by Women's Health at Stanford.
Although miscarriage is common - 30 percent of all women will experience at least one miscarriage in their lifetime, and 1-2 percent will have three or more - there have been relatively few well-conducted studies on its causes and treatments, said Ruth Lathi, MD, Director of the Recurrent Pregnancy Loss Program at Stanford Hospital & Clinics and assistant professor of obstetrics and gynecology. "We can do better than this. We need more research," she said.
As many as 40 to 50 percent of miscarriages have no identifiable cause.
Some of miscarriage's causes have been pinpointed. Endocrine problems, such as thyroid disease, are responsible for 15-20 percent of miscarriages; hypercoagulability, an increased tendency to develop blood clots, also causes 15-20 percent; maternal abnormalities in the uterus or cervix cause 10-15 percent; maternal genetic mutation causes 2-5 percent; and in 0.5-5 percent of cases, infection triggers a miscarriage. Older age and a history of previous miscarriages also increase the risk.
Some of these causes can be detected and treated. For women with thyroid dysfunction (hypothyroidism or hyperthyroidism), successful treatment reduces the risk of miscarriage and other adverse outcomes. For women with thyroid dysfunction (hypothyroidism or hyperthyroidism), successful treatment reduces the risk of miscarriage and other adverse outcomes. Recent studies have also shown that in selected women who have anti-thyroid antibodies (a condition affecting about 11 percent of reproductive-age women), treatment with the thyroid hormone levothyroxine can effectively decrease miscarriage rates.
Women who have hypercoagulability can be treated with therapies that interfere with blood clot formation, most commonly aspirin or heparin or both. Weight is another contributing factor, said Sun Kim, MD, assistant professor of medicine in the Division of Endocrinology. Research finds that being obese or underweight significantly increases pregnancy complications and the risk of miscarriage.
Given that one-third of Americans are obese, the impact of obesity on pregnancy outcomes is a growing public-health concern, Kim said. "Losing weight is hard, I don't deny that," she said. But she added that even moderate weight loss of 5-10 percent can significantly reduce the risk of miscarriage.