Objective: The purpose of this study was to investigate the genetic background for the previously reported finding of an increased frequency of low levels of mannan-binding lectin in couples with unexplained recurrent spontaneous abortion and to evaluate the impact of low mannan-binding lectin levels on future pregnancy outcome.
Study designs: Mannan-binding lectin levels were measured in 217 women with unexplained recurrent spontaneous abortion and 111 of their husbands and were compared with corresponding measurements in 104 couples with uncomplicated reproductive histories and 210 blood donors. An investigation of the genetic polymorphism, which is largely responsible for serum mannan- binding lectin levels, was done by polymerase chain reaction methods with DNA from a subset of the patients and control subjects. Information was collected about the outcome of the patients' next pregnancies, together with perinatal data concerning the patients' first birth that occurred before or after being assigned to the study.
Results: Among women with recurrent spontaneous abortion, 18.9% of the women had mannan-binding lectin levels of </= 100 ng/mL compared with 12.2% of control subjects ( P =.02). An investigation of mannan-binding lectin levels and genetic analyses gave no evidence that paternal mannan- binding lectin deficiency plays a role for recurrent spontaneous abortion. Patients with mannan-binding lectin levels of </=100 ng/mL had a higher abortion rate than patients with normal mannan- binding lectin levels (P <.05). The median birth weight of children who were born at term of women with recurrent spontaneous abortion was 287 g less in women with mannan-binding lectin levels of </= 100 ng/mL than that of patients with normal mannan-binding lectin levels (P =.04).
Conclusion: Low maternal serum mannan-binding lectin levels exhibit a negative impact on pregnancy outcome in women with unexplained recurrent spontaneous abortion.