Changing trends in operative delivery performed at full dilatation over a 10-year period.

This study was a systematic anonymous audit of routinely collected data in a tertiary referral obstetric unit in London and included data from deliveries over a 10-year period (1992-2001). Data for all caesarean sections at full dilatation were collected, including maternal demographic information, the grade of operating clinician, and the place of delivery. Neonatal data collected included birth weight and umbilical arterial pH. No changes in the demographics of the population were observed. No increased rates of malposition were observed. Birth weight did not change. Increasing preference for the ventouse over forceps (ratio 0.2:1 to 1.9:1) over the decade (p = 0.002) was seen with an increased tendency to conduct the delivery in the operating theatre (p = 0.0025). Rate of caesarean section at full dilatation increased (2% by 2001). Increasing failures of operative vaginal delivery, especially using the ventouse (regression coefficient p = 0.025), and reduced attempts at instrumentation (regression coefficient p = 0.002) were seen.

The mitogen-activated protein kinase dependent expression of prostaglandin H synthase-2 and interleukin-8 messenger ribonucleic acid by myometrial cells: the differential effect of stretch and interleukin-1{beta}.

Infection and uterine stretch are the common causes of preterm labor. IL-1beta plays a key role in infection-induced preterm labor and increases prostaglandin H synthase 2 (PGHS-2) and IL-8 expression. We have shown that mechanical stretch of uterine myocytes in vitro up-regulates the expression of PGHS-2 and IL-8. In this study, we tested the hypotheses that both IL-1beta and mechanical stretch increase the myometrial expression of PGHS-2 and IL-8 via MAPK activation and that their effects are synergistic. MAPK activation was assessed in myocytes obtained from pregnant women undergoing cesarean section before the onset of labor after exposure to IL-1beta and stretch either alone or in combination. Specific inhibitors of ERK, p38, and c-Jun N-terminal kinase were used to define the role of each in the increased expression of PGHS-2 and IL-8 mRNA. We found that both IL-1beta and stretch activated all three MAPK subtypes but that they had no synergistic effect. The inhibitor studies showed that stretch-induced increases in both PGHS-2 and IL-8 mRNA expression were ERK1/2 and p38 dependent and that IL-1beta-induced increases of PGHS-2 mRNA expression were also ERK1/2 and p38 dependent, but those of IL-8 were dependent only on ERK1/2 activation. These data show that exposure of human uterine myocytes to both stretch and IL-1beta activates the MAPK system, which is responsible for the increase in PGHS-2 and IL-8 mRNA expression. We found no evidence of a synergistic effect of IL-1beta and stretch on myometrial expression of PGHS-2 and IL-8 mRNA.

Mechanical stretch of human uterine smooth muscle cells increases IL-8 mRNA expression and peptide synthesis.

Labour is associated with increased synthesis of interleukin-8 (IL-8) by the fetal membranes and myometrium, which leads to an inflammatory infiltrate. Stretch has been shown to increase the expression of contraction-associated proteins in animal models of labour and in human myocytes in vitro. In this study, we tested the hypothesis that mechanical stretch of human myometrial cells increases IL-8 messenger ribonucleic acid (mRNA) expression. We isolated myocytes from non-pregnant women undergoing hysterectomy and pregnant women undergoing Caesarean section before and after the onset of labour. Myocytes in culture were subjected to stretch of varying intensity (6-16%) and duration (1 or 6 h) using the Flexercell system. IL-8 mRNA expression was lowest in myocytes from pregnant women not in labour, intermediate in those from non-pregnant women and greatest in those from pregnant women in labour. Stretch increased IL-8 mRNA expression independent of reproductive state. The stretch-induced increase in IL-8 mRNA expression was associated with higher IL-8 levels in the culture supernatant and enhanced promoter activity. These data suggest that stretch contributes to the increase in myometrial IL-8 synthesis associated with the onset of labour in humans.