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Obstet Gynecol. 2005 Nov;106(5 Pt 1):993-9.

Risk factors for spontaneous abortion in early symptomatic first-trimester pregnancies.

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  • 1Department of Obstetrics & Gynecology, Penn Fertility Care, University of Pennsylvania Medical Center, 3701 Market Street, Philadelphia, PA 19104, USA.



To evaluate the association of an ultimate diagnosis of miscarriage with various clinical symptoms and historical factors in a cohort of women presenting with pain, bleeding, or both in the first trimester of pregnancy.


This was a case-control study from a population of women presenting for care with pelvic pain or vaginal bleeding in the first trimester of pregnancy whose diagnoses were not definite upon initial evaluation. Analyses were performed in 2 ways. In one instance cases were defined as women ultimately definitively diagnosed with a miscarriage and controls were defined as women with a pregnancy that did not result in miscarriage (ectopic pregnancy or ongoing intrauterine pregnancy). The second analysis compared women with a miscarriage only to women who had an ongoing intrauterine pregnancy.


A total of 2,026 women were evaluated, with 1,192 ultimately diagnosed with a spontaneous abortion, 367 with ectopic pregnancy, and 467 with a viable intrauterine pregnancy. Although many risk factors were individually associated with miscarriage in preliminary analysis, in the final analysis only extremes in age (< 25 and > 35) and the complaint of bleeding (odds ratio [OR] 7.35, 95% confidence interval[CI] 5.74-9.41) were associated with miscarriage. The complaint of pain (OR 0.72, 95% CI 0.57-0.92), human chorionic gonadotropin (hCG) value greater than 500 (hCG < or = 500 IU/mL compared with hCG 501-2000: OR 0.52, 95% CI 0.39-0.69) and concurrent cervical infection (OR 0.69, 95% CI 0.55-0.88) were negatively associated with miscarriage.


Few factors predict miscarriage in women who present with a symptomatic first trimester pregnancy of unknown location. Heavy bleeding was most strongly associated with miscarriage. Concurrent cervical infections should not be overlooked as a cause of bleeding in early pregnancy and were not associated with miscarriage.



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