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Objective To develop and internally validate a model that predicts the outcome of an intended vaginal birth after caesarean (VBAC) for a Western European population that can be used to personalise counselling for deliveries at term.Design Registration-based retrospective cohort study.Setting Five university teaching hospitals, seven non-university teaching hospitals, and five non-university non-teaching hospitals in the Netherlands.Population A cohort of 515 women with a history of one caesarean section and a viable singleton pregnancy, without a contraindication for intended VBAC, who delivered at term.Methods Potential predictors for a vaginal delivery after caesarean section were chosen based on literature and expert opinions. We internally validated the prediction model using bootstrapping techniques.Main outcome measures Predictors for VBAC. For model validation, the area under the receiver operating characteristic curve (AUC) for discriminative capacity and calibrationper-risk-quantile for accuracy were calculated.Results A total of 371 out of 515 women had a VBAC (72%). Variables included in the model were: estimated fetal weight greater than the 90 th percentile in the third trimester; previous non-progressive labour; previous vaginal delivery; induction of labour; pre-pregnancy body mass index; and ethnicity. The AUC was 71% (95% confidence interval, 95% CI = 69-73%), indicating a good discriminative ability. The calibration plot shows that the predicted probabilities are well calibrated, especially from 65% up, which accounts for 77% of the total study population. ConclusionWe developed an appropriate Western European population-based prediction model that is aimed to personalise counselling for term deliveries.

Summary:A single umbilical cord blood (UCB) collection may contain sufficient hematopoietic stem cells to achieve engraftment and repopulation of the hematopoietic system of children and adults after myeloablative therapy. The hematopoietic potential of a UCB unit is often defined by the number of CD34 + cells or the number of colony-forming units as measured in semisolid hematopoietic progenitor cell (HPC) cultures. However, these assays are relatively difficult to standardize between UCB banks. The number of nucleated cells infused per kilogram body weight of the recipient is also reported to be a significant factor in the speed of recovery of neutrophils and platelets after transplantation. To analyze which parameters could be used to evaluate the hematopoietic potential of a UCB graft, we evaluated almost 300 UCB units that were collected for banking for unrelated transplantation. A strong correlation was found between the frequencies of CD34 + cells and the HPC as measured in semi-solid medium cultures. From the various leukocyte subpopulations, the concentration and total numbers of nucleated cells correlated best with both the HPC content and the number of CD34 + cells. Differentiation of these nucleated cells into subsets of leukocytes offered no advantage for better prediction of HPC or CD34 + cells. These results indicate that the nucleated cell count probably reflects the hematopoietic potential of a UCB graft, and may for that reason correlate with the speed of engraftment after transplantation.

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Umbilical cord blood (UCB) has been successfully used as an alternative source of hematopoietic stem cells for allogeneic transplantation. A relatively low incidence and severity of graft-versus-host disease (GVHD) following UCB transplants has been reported, and it has been suggested that this may be caused by a low frequency of alloreactive lymphocytes in UCB. Low frequencies of alloreactive T lymphocytes in UCB may allow transplantation across major MHC barriers with an acceptable risk of GVHD. We investigated cytotoxic T-lymphocyte precursor (CTLp) and helper T-lymphocyte precursor (HTLp) frequencies in UCB. Normal frequencies of CTLp and HTLp were measured against 1-2 HLA class I and 0-1 HLA-DR mismatched stimulator cells. Since it has been postulated that due to maternal fetal transfusion during pregnancy, fetal blood lymphocytes may become tolerant for noninherited maternal antigens (NIMA), allowing transplantation over certain HLA barriers, reactivity of 24 umbilical cord blood samples was analyzed against both parents. The median frequencies of CTLp against NIMA with 1 class-I mismatch was 79 per 10(6) nucleated cells (range 16-428) and with 2 class I mismatches 121 (range 33-748). CTLp frequencies against noninherited paternal antigens (NIPA) were not statistically different from those against NIMA, with a median of 115 (range 8-336) and 176 (range 50-725) for 1 or 2 HLA class I mismatches, respectively. HTLp frequencies in UCB against parents with 0 or 1 HLA-DR antigen mismatches were similar with respect to NIMA (median 74, range 43-233 and 88, range 16-777, respectively) and NIPA (median 125, range 18-174, and 110, range 28-350, respectively). In four cases, UCB from two HLA-identical siblings was tested against both parents. A correlation between the frequencies of CTLp and HTLp from HLA-identical individuals was found, illustrating that these frequencies are genetically determined. These results illustrate that UCB contains normal frequencies of CTLp and HTLp against MHC alloantigens.