Prediction of preterm delivery by second trimester inflammatory biomarkers in the amniotic fluid

Abstract

Objective: To search for a correlation between mid-pregnancy altered levels of inflammatory markers and preterm delivery.

Methods: A prospective cohort series included 39 patients undergoing amniocentesis one additional milliliter of amniotic fluid (AF) was stored for later dosage of interleukin-6 (Il-6), matrix metalloproteinase-9 (MMP-9), glucose and C-reactive protein (CRP). Maternal serum CRP and glucose levels were also obtained. Exclusion criteria were multiple pregnancies, chorioamnionitis, group B streptococcus colonization, bacterial vaginosis and cases with proven aneuploidy. We searched for correlation between AF and plasmatic markers and also for a difference between patients with term and preterm delivery.

Results: 33 participants were eligible and one third had preterm delivery. Levels of the plasmatic biomarkers did not correlate with the AF biomarkers except for plasmatic glucose and AF IL-6 levels (r=0.350; p=0.016). The levels of all AF biomarkers did not differ significantly between the pre-term and the term groups (p>0.05). The optimal screening cutoffs for identifying pregnancies at risk were different than the ones initially indicated.

Conclusion: Mid-pregnancy amniotic fluid biomarker levels do not correlate with preterm delivery. Plasma CRP is not correlated with these markers. Cutoff levels suggested are sparse and heterogeneous. Larger studies are needed before advising routine measurement of these markers.

Keywords: Amniotic fluid; Antenatal; Inflammation; Interleukins; MMP-9; Prediction; Preterm.