Fetal development and growth occur in a sterile amniotic cavity while first exposure to microorganisms happens at birth. However, at least 25% of all preterm births, the leading cause of perinatal morbidity and mortality worldwide, occur in mothers with microbial invasion of the amniotic cavity. Microbial attack of the fetus takes place in approximately 10% of pregnancies with intra-amniotic infection, and the human fetus is capable of deploying an inflammatory response (cellular and humoral) in the mid-trimester of pregnancy. The onset of premature labor in the context of infection is mediated by pro-inflammatory cytokines, such as interleukin (IL)-1beta and tumor necrosis factor alpha (TNF-alpha), as these cytokines are produced by intrauterine tissues in response to microbial products, can stimulate prostaglandin production, and induce labor in animals. Moreover, knockout experiments suggest that infection is less likely to lead to premature labor when the IL-1 and TNF signaling pathways are disrupted. A fetal inflammatory systemic response occurs in a fraction of fetuses exposed to microorganisms in utero, and is associated with the impending onset of labor as well as multisystem organ involvement. Neonates born with funisitis, the histologic marker of such inflammation, are at increased risk for neurologic handicap and cerebral palsy. Evidence has begun to accumulate that gene-environment interactions determine the likelihood of preterm labor and delivery and, probably, the risk of fetal injury. Fetal inflammation has emerged as a major mechanism of disease responsible for complications in the perinatal period (in utero and in the first 28 days of life), as well as in infancy. Moreover, reprogramming of the fetal immune response may predispose to diseases in adulthood.

OBJECTIVE-Changes in the maternal plasma concentrations of angiogenic (such as PlGF and VEGF) and anti-angiogenic factors (such as sEng and sVEGFR-1) precede the clinical presentation of preeclampsia. This study was conducted to examine the role of maternal plasma PlGF, sEng and sVEGFR-1 concentrations in early pregnancy and midtrimester in the identification of patients destined to develop preeclampsia.METHODS-This longitudinal cohort study included 1,622 consecutive singleton pregnant women. Plasma samples were obtained in early pregnancy (6-15 weeks) and midtrimester (20-25 weeks). Maternal plasma PlGF, sEng and sVEGFR-1 concentrations were determined using sensitive and specific immunoassays. The primary outcome was the development of preeclampsia. Secondary outcomes included term, preterm and early-onset preeclampsia. Receiving operating characteristic (ROC) curves, sensitivity, specificity, positive and negative likelihood ratios, and multivariable logistic regression were used for statistical analyses. A p-value of <0.05 was considered significant. RESULTS-1)The prevalence of preeclampsia, term, preterm (<37 weeks) and early-onset preeclampsia (<34 weeks) was 3.8% (62/1,622), 2.5% (40/1,622), 1.4% (22/1,622) and 0.6% (9/1,622), respectively; 2) Higher likelihood ratios were provided by ratios of midtrimester plasma concentrations of PlGF, sEng, and sVEGFR-1 than single analytes; 3) Individual angiogenic and anti-angiogenic factors did not perform well in the identification of preeclampsia as a whole; in particular, they perform poorly in the prediction of term preeclampsia; 4) In contrast, a NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript combination of these analytes such as the PlGF/sEng ratio, its delta and slope had the best predictive performance with a sensitivity of 100%, a specificity of 98%-99%, and likelihood ratios for a positive test of 57.6, 55.6 and 89.6, respectively, for predicting early-onset preeclampsia. CONCLUSIONS-1)The PlGF/sEng ratio and its delta and slope had an excellent predictive performance for the prediction of early-onset preeclampsia, with very high likelihood ratios for a positive test result and very low likelihood ratios for a negative test result; and 2) Although the positive likelihood ratios are high and the positive predictive values low, the number of patients needed to be closely followed is 4:1 for the PlGF/sEng ratio and 3:1 for the slope of PlF/sEng.

No abstract

Objective Fragment Bb is an activator of the alternative pathway of the complement system. Recently, increased first trimester maternal plasma concentrations of this fragment were reported in patients destined to have a spontaneous preterm delivery before 34 weeks of gestation. The aim of this study was to determine whether the amniotic fluid (AF) concentrations of fragment Bb change with gestational age, spontaneous labor (term and preterm), and in the presence of intra-amniotic infection/ inflammation (IAI). Study design This cross-sectional study included patients in the following groups: 1) midtrimester (n=64); 2) term in spontaneous labor (n=70); 3) term not in labor (n=43); 4) spontaneous preterm labor (PTL) who delivered at term (n=76); 5) PTL without IAI who delivered preterm (n=73); 6) PTL with IAI (n=76); 7) prelabor rupture of the membranes (preterm PROM) without IAI (n=71); and 8) preterm PROM with IAI (n=71). Fragment Bb concentration in amniotic fluid was determined by an enzyme-linked immunoassay. Non-parametric statistics were used for analyses. Results 1) Fragment Bb was detected in all AF samples (n=544); 2) The median AF concentration of fragment Bb in patients at term not in labor was significantly higher than that of those in the mid-trimester [2.42 μg/mL, interquartile range (IQR) 1.78-3.22 vs. 1.64 μg/mL, IQR 1.06-3.49; p<0.001]; 3) Among patients with PTL, those with IAI had a higher median AF fragment Bb concentration than that of woman without IAI who delivered preterm (4.82 μg/mL, IQR 3.32-6.08 vs. 3.67 μg/mL, IQR 2.35-4.57; p<0.001) and than that of women with an episode of PTL who delivered at term (3.21 μg/mL, IQR 2.39-4.16; p<0.001); 4) Similarly, among patients with preterm PROM, the median AF fragment Bb concentration was higher in individuals with IAI than in those without IAI (4.24 μg/mL, IQR 2.58-5.79 vs. 2.79 μg/mL, IQR 2.09-3.89; p<0.001). 5) Among patients at term, the median AF fragment Bb concentration did not differ between women with spontaneous labor and those without labor (term in labor: 2.47 μg/mL, IQR 1.86-3.22; p=0.97). Conclusions 1) Fragment Bb, an activator of the alternative complement pathway, is a physiologic constituent of the amniotic fluid, and its concentration increases with advancing gestational age; 2) Amniotic fluid concentrations of fragment Bb are higher in pregnancies complicated with IAI; and 3) Labor at term is not associated with changes in the amniotic fluid concentrations of fragment Bb. These findings suggest a role for fragment Bb in the host immune response against IAI.