Amniotic fluid cell-free DNA in preterm prelabor rupture of membranes

Abstract

Introduction: We evaluated the levels of cell-free nuclear DNA (nDNA) and cell-free mitochondrial DNA (mtDNA) in the amniotic fluid supernatant from pregnancies complicated by preterm prelabor rupture of membranes (PPROM) based on evidence of microbial invasion of the amniotic cavity (MIAC) and/or intra-amniotic inflammation (IAI).

Material and methods: A total of 155 women with PPROM were included in this study. Amniotic fluid samples were obtained by transabdominal amniocentesis. The levels of cell-free nDNA and mtDNA in the amniotic fluid supernatant were assessed and quantified by real-time polymerase chain reaction.

Results: The levels of cell-free nDNA and mtDNA were higher in women with MIAC and IAI than in women without these conditions (nDNA: with MIAC: median 3.9 × 10⁴ genome equivalent [GE]/mL vs without MIAC: median 1.2 × 10⁴ GE/mL, with IAI: median: 5.3 × 10⁴ GE/mL vs without IAI: median 1.2 × 10⁴ GE/mL; mtDNA: with MIAC: median 9.2 × 10⁵ GE/mL vs without MIAC: median 2.5 × 10⁵ GE/mL, with IAI: median 1.1 × 10⁶ GE/mL vs without IAI: median 2.5 × 10⁵ ; all P values ≤ 0.01). Women with the microbial-associated IAI showed the highest levels of cell-free nDNA and mtDNA.

Conclusions: Cell-free nDNA and mtDNA are constituents of the amniotic fluid supernatant from PPROM pregnancies. Both cell-free nDNA and mtDNA are involved in the intra-amniotic inflammatory response in women with PPROM.