Objective: The purpose of this study was to determine whether the vaginal cytokine concentration varies during the course of uncomplicated pregnancy.
Study design: Prenatal visits of healthy women to University Hospital Gasthuisberg, Leuven, Belgium were considered. Cytokine levels in vaginal washings from 30 unselected healthy women with uncomplicated pregnancies were monitored during pregnancy and compared with those from 62 nonpregnant healthy control subjects. Exclusion criteria included bacterial vaginosis, moderate or severe aerobic vaginitis, Trichomonas vaginalis, Candida vaginitis (wet mount or culture), gonorrhea, and Chlamydia. Interleukin-6, interleukin-8, interleukin-1beta, interleukin-1-receptor antagonist, leukemia inhibitory factor, and tumor necrosis factor were measured. Nonparametric Kruskal-Wallis and Welch tests were used for univariate analysis, and the Spearman rank test was used for multivariate analysis.
Results: Compared with concentrations in nonpregnant women, interleukin-1beta concentrations were similar, but interleukin-1-receptor antagonist production was depressed throughout pregnancy. Vaginal interleukin-6 and interleukin-8 were less often discovered during pregnancy than outside pregnancy and dipped significantly in the middle trimester, to rise again to prepregnancy levels in the third trimester. Leukemia inhibitory factor was lower during the beginning of pregnancy (P=.038) but otherwise did not differ from nonpregnant values throughout pregnancy nor did tumor necrosis factor. Sexual activity could not explain these findings.
Conclusion: Vaginal cytokine levels, especially interleukin-1 receptor antagonist, from pregnant women may differ from nonpregnant values; some levels, such as interleukin-6 and interleukin-8, may fluctuate during normal pregnancy. These spontaneous variations during pregnancy must be taken into account when mucosal immunologic responses to infection of the lower genital tract are being studied.