Second-trimester plasma mannose-binding lectin levels and risk of preterm birth

Objective: To investigate whether mannose-binding lectin (MBL) gene polymorphisms and low levels of second-trimester plasma MBL were significant risk factors for preterm birth in Taiwanese women. Methods: We conducted a prospective longitudinal study to explore the associations of MBL2 gene single nucleotide polymorphisms and plasma MBL levels between preterm birth and term controls. Blood samples were collected at 16-23 weeks of gestation, and were divided into 51 mothers with preterm births and 255 term controls after delivery. Blood samples were further collected at delivery from 11 mothers with term delivery and 9 with preterm births. DNA was isolated, and polymorphisms in exon 1, the promoter untranslated regions of MBL2 were determined by polymerase chain reaction. The plasma concentrations of MBL were measured by enzyme-linked immunosorbent assay. Results: There is a positive correlation between SNP genotypes and second-trimester plasma MBL levels. Among mothers with preterm births, a higher frequency of specific genotypes with low MBL levels was not observed. The second-trimester plasma MBL levels were not significantly different between mothers with preterm births (N=51) and term deliveries (N=255). However, among mothers (N=11) with term pregnancies, the MBL plasma level significantly increased from the second trimester to delivery, whereas in mothers (N=9) who developed preterm delivery, the MBL level did not significantly change. Conclusion: Genotypes associated with low levels of plasma MBL during pregnancy did not increase the risk of preterm births. A low second-trimester plasma MBL level is therefore not a predictor for the development of preterm birth.