The Normal anticoagulant system and risk of placental abruption: protein C, protein S and resistance to activated protein C.

OBJECTIVE

To examine the association between maternal thrombophilia associated with anticoagulation (proteins C and S and activated protein C resistance ratio, APCR) and risk of placental abruption.

METHODS

Data were derived from a case-control study - The New Jersey-Placental Abruption Study (2002-2007). Maternal blood was collected from abruption cases and controls and was assayed for the thrombophilias. Decreased protein C, S and APCR was defined as values <5% and <10% among controls.

RESULTS

Of a total of 132 cases and 127 controls, 3 were heterozygous for the factor V Leiden mutation (1 case and 2 controls). Mean (± standard deviation) protein C (114.2 ± 25.6 vs. 121.4 ± 27.6; P=0.009), protein S (39.9 ± 18.4 vs. 35.7 ± 15.2; P=0.043) and APCR (2.86 ± 0.29 vs. 2.88 ± 0.27; P=0.039) were different between cases and controls. Abruption cases were associated with an odds ratio of 3.2 (95% CI 1.2, 9.9) in relation to decreased protein C (<Fifth centile). Decreases in both protein S and APCR ratio were not associated with abruption.

CONCLUSIONS

A decrease in protein C was associated with an increased risk for abruption, suggesting an important role for the physiologic anticoagulant system in the etiology of placental abruption.