Healthy pregnancy is the most successful form of graft tolerance, whereas preterm labor (PTL) may represent a breakdown in maternal-fetal tolerance. Although maternal immune responses have been implicated in pregnancy complications, fetal immune responses against maternal antigens are often not considered. To examine the fetal immune system in the relevant clinical setting, we analyzed maternal and cord blood in patients with PTL and healthy term controls. We report here that the cord blood of preterm infants has higher amounts of inflammatory cytokines and a greater activation of dendritic cells. Moreover, preterm cord blood is characterized by the presence of a population of central memory cells with a type 1 T helper phenotype, which is absent in term infants, and an increase in maternal microchimerism. T cells from preterm infants mount a robust proliferative, proinflammatory response to maternal antigens compared to term infants yet fail to respond to third-party antigens. Furthermore, we show that T cells from preterm infants stimulate uterine myometrial contractility through interferon-γ and tumor necrosis factor-α. In parallel, we found that adoptive transfer of activated T cells directly into mouse fetuses resulted in pregnancy loss. Our findings indicate that fetal inflammation and rejection of maternal antigens can contribute to the signaling cascade that promotes uterine contractility and that aberrant fetal immune responses should be considered in the pathogenesis of PTL.

Purpose Fetal hydrops arises from multiple disease processes and can portend a grim prognosis. We reviewed our experience with hydropic fetuses to understand relevant antenatal anatomic and physiologic predictors of survival. Methods We reviewed fetal ultrasounds and echocardiograms of hydropic fetuses evaluated from 1996-2013. Results Overall neonatal survival in 167 fetuses was 44% (range, 0-75%) and was influenced by the underlying disease process. The anatomic distribution of fluid varied and was not significantly different between survivors and non-survivors. Univariate analysis indicated that resolution of hydrops and delivery at a later gestational age were predictive of survival (OR:5.7 (95% CI:2.5-13.2) and OR:1.3 (95% CI:1.1-1.4), respectively). Fetal intervention also improved survival in some diseases. Echocardiograms were reviewed to group fetuses with similar cardiac physiology and defined categories with high or low/normal cardiothoracic ratio (CTR). Among patients with a high CTR, the cardiovascular profile score was predictive of survival (p=0.009). Conclusion Survival in hydrops depends on the underlying disease, available fetal therapies to resolve hydrops, and the gestational age of delivery and not on the specific anatomic manifestations of hydrops. In hydropic fetuses with high CTRs, the cardiovascular profile score may be a useful prognostic indicator.

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