Third-trimester unexplained intrauterine fetal death is associated with inherited thrombophilia

To determine the risk of thrombophilias in women with unexplained intrauterine fetal deaths (IUFD).

All women with IUFD at 27 weeks' gestation or greater were initially assessed during a period of 26 months. Subjects with multiple pregnancies, congenital anomalies, intrauterine infection, chorioamnionitis, immune hydrops, diabetes mellitus, previous thromboembolism, and severe hypertensive disease were excluded. The remaining 40 women with unexplained IUFD (study group) were matched for age and ethnicity with 80 healthy women who had at least one normal pregnancy (control group). All participants were tested at least 2 months after delivery for mutations of factor V Leiden, prothrombin gene, methylenetetrahydrofolate reductase, and for deficiencies of protein S, protein C, and antithrombin III. They were also tested and found to be negative for anticardiolipin antibodies.

The gestational age at delivery and birth weight were significantly lower in the study group. The prevalence of inherited thrombophilias was 42.5% in the study group compared with 15% in the control group (odds ratio 2.8, 95% confidence interval 1.5, 5.3, P =.001). The prothrombin mutation and protein S deficiency rates were significantly higher in the study group (odds ratio 2.3, 95% confidence interval 1.3, 4.0, and odds ratio 3.2, 95% confidence interval 2.4, 4.1, respectively).

Third-trimester IUFD is significantly associated with thrombophilias. These findings suggest that thrombophilia work-ups should be part of IUFD investigations and may have therapeutic and prognostic implications in future pregnancies.