Photo Credit: Rasi Bhadramani

The following is a summary of “Activation of peripheral leukocyte migration before spontaneous labor at term,” published in the November 2024 issue of Obstetrics and Gynecology by Lee et al.    

Leukocytes are attracted to the uterus during labor, releasing cytokines and chemokines to activate delivery. Evidence suggests the fetal membranes release signals that induce leukocyte migration, with increased migration observed in labor.  

Researchers conducted a prospective study to examine the timing and factors affecting leukocyte migration before labor and predictive potential for delivery.  

They studied leukocyte migration in response to a chemoattractive extract of term human fetal membranes using a modified Boyden chamber. Flow cytometry was used to assess migrated cell phenotypes. The relationship between chemokine receptor expression and migration was tested with quantitative polymerase chain reaction (PCR), bioassay, and regression analyses. Cytokines and chemokines in maternal serum were quantified via multiplex analysis. Using a bioassay, a conditioned medium from fetal membrane explants and maternal serum were tested for leukocyte migration. The bioassay’s ability to predict term delivery was assessed with ROC and cost-curve analysis.  

The results showed that leukocyte migration significantly increased at term compared to the late third trimester, then decreased 3 days postpartum (P=.002). The highest increase in migration occurred 1 to 2 weeks before delivery. Chemokine receptor messenger ribonucleic acid (mRNA) abundance in peripheral leukocytes increased at term labor, correlating with migration in 5 of 6 cases (R=0.589 to 0.897; P<.03). Maternal serum cytokines and chemokines increased with labor onset. Fetal membrane-conditioned medium and maternal serum from labor enhanced leukocyte migration. The assay effectively predicted delivery within 7 days, with a positive predictive value of 96.1%, negative predictive value of 58.5%, sensitivity of 74.2%, specificity of 92.3%, positive likelihood ratio of 9.25, and negative likelihood ratio of 0.28.  

They concluded that fetal membranes release chemoattractants that increase leukocyte migration as labor approaches, which could be used to predict delivery timing.  

Source: ajog.org/article/S0002-9378(24)00360-0/fulltext