Early second trimester maternal plasma levels of thrombin-inhibitor complexes and subsequent spontaneous preterm delivery.

OBJECTIVE

Increased thrombin generation has been implicated as a mechanism for several obstetric syndromes including preterm birth preceded by preterm labor (PTL) and preterm premature rupture of membranes (PPROM). In this study, we attempted to determine whether PTL or PPROM are associated with changes in the maternal plasma thrombin level during the early second trimester.

METHODS

This is a case-control study in which maternal thrombin-antithrombin (TAT) III complex concentrations at 15-21 weeks were compared between normal controls (n = 85) and women subsequently delivering preterm, due to either PTL with intact membranes (n = 21) or PPROM (n = 20). Statistical analysis was conducted using non-parametric statistics.

RESULTS

PTL patients with intact membranes showed non-significant differences in median plasma TAT level (110.1 µg/L) compared with the control group (107.9 µg/L). Similarly, women destined to deliver preterm because of PPROM had non-significantly higher plasma TAT level (134.3 µg/L) than those in the control group (107.9 µg/L) (p > 0.05). Logistic regression analysis demonstrated that after controlling for confounders including vaginal bleeding, TAT levels remained not significantly associated with subsequent spontaneous preterm birth (p = 0.27).

CONCLUSION

Maternal plasma TAT level is unsuitable as an early second trimester predictor of preterm birth preceded by PTL or PPROM.