Risk of obstetric anal sphincter injury in women having a vaginal birth after a previous caesarean section: A population-based cohort study.

OBJECTIVE: Caesarean section is increasing in prevalence and with it the proportion of women going into their next pregnancy with a scar on their uterus. For women considering vaginal birth after caesarean (VBAC), accurate information about the associated risks is required. STUDY DESIGN: The cohort comprised 192,057 women who had a vaginal delivery of a singleton, term, cephalic infant between the 1st April 2013 and the 31st March 2014 in England: 182,064 women who were having their first baby, and 9993 women who were having a second baby after a previous caesarean delivery. Their risk of an obstetric anal sphincter injury (OASI) was compared using a mixed-effects logistic regression model, adjusting for maternal age, use of instrument, episiotomy, prolonged labour, shoulder dystocia, and demographic factors. RESULTS: The OASI rate was 5.0% in primiparous women, 5.8% in secondiparous women undergoing VBAC after previous elective caesarean, and 7.6% in secondiparous women undergoing VBAC after previous emergency caesarean. Women having a VBAC for their second baby following an emergency caesarean section in their first delivery had a higher rate of OASI than primiparous women (adjusted OR 1.31; 95% CI: 1.20, 1.43), For women with a previous elective delivery, the rates are similar to those for primiparous women. CONCLUSION: Women having a VBAC after emergency caesarean have a higher rate of OASI than primiparous women. This is important in the counselling of women considering VBAC.

Perinatal mortality associated with induction of labour versus expectant management in nulliparous women aged 35 years or over: An English national cohort study.

BACKGROUND: A recent randomised controlled trial (RCT) demonstrated that induction of labour at 39 weeks of gestational age has no short-term adverse effect on the mother or infant among nulliparous women aged ≥35 years. However, the trial was underpowered to address the effect of routine induction of labour on the risk of perinatal death. We aimed to determine the association between induction of labour at ≥39 weeks and the risk of perinatal mortality among nulliparous women aged ≥35 years. METHODS AND FINDINGS: We used English Hospital Episode Statistics (HES) data collected between April 2009 and March 2014 to compare perinatal mortality between induction of labour at 39, 40, and 41 weeks of gestation and expectant management (continuation of pregnancy to either spontaneous labour, induction of labour, or caesarean section at a later gestation). Analysis was by multivariable Poisson regression with adjustment for maternal characteristics and pregnancy-related conditions. Among the cohort of 77,327 nulliparous women aged 35 to 50 years delivering a singleton infant, 33.1% had labour induced: these women tended to be older and more likely to have medical complications of pregnancy, and the infants were more likely to be small for gestational age. Induction of labour at 40 weeks (compared with expectant management) was associated with a lower risk of in-hospital perinatal death (0.08% versus 0.26%; adjusted risk ratio [adjRR] 0.33; 95% CI 0.13-0.80, P = 0.015) and meconium aspiration syndrome (0.44% versus 0.86%; adjRR 0.52; 95% CI 0.35-0.78, P = 0.002). Induction at 40 weeks was also associated with a slightly increased risk of instrumental vaginal delivery (adjRR 1.06; 95% CI 1.01-1.11, P = 0.020) and emergency caesarean section (adjRR 1.05; 95% CI 1.01-1.09, P = 0.019). The number needed to treat (NNT) analysis indicated that 562 (95% CI 366-1,210) inductions of labour at 40 weeks would be required to prevent 1 perinatal death. Limitations of the study include the reliance on observational data in which gestational age is recorded in weeks rather than days. There is also the potential for unmeasured confounders and under-recording of induction of labour or perinatal death in the dataset. CONCLUSIONS: Bringing forward the routine offer of induction of labour from the current recommendation of 41-42 weeks to 40 weeks of gestation in nulliparous women aged ≥35 years may reduce overall rates of perinatal death.

A guide to evaluating linkage quality for the analysis of linked data.

Linked datasets are an important resource for epidemiological and clinical studies, but linkage error can lead to biased results. For data security reasons, linkage of personal identifiers is often performed by a third party, making it difficult for researchers to assess the quality of the linked dataset in the context of specific research questions. This is compounded by a lack of guidance on how to determine the potential impact of linkage error. We describe how linkage quality can be evaluated and provide widely applicable guidance for both data providers and researchers. Using an illustrative example of a linked dataset of maternal and baby hospital records, we demonstrate three approaches for evaluating linkage quality: applying the linkage algorithm to a subset of gold standard data to quantify linkage error; comparing characteristics of linked and unlinked data to identify potential sources of bias; and evaluating the sensitivity of results to changes in the linkage procedure. These approaches can inform our understanding of the potential impact of linkage error and provide an opportunity to select the most appropriate linkage procedure for a specific analysis. Evaluating linkage quality in this way will improve the quality and transparency of epidemiological and clinical research using linked data.

Birth "Out-of-Hours": An Evaluation of Obstetric Practice and Outcome According to the Presence of Senior Obstetricians on the Labour Ward.

BACKGROUND: Concerns have been raised that a lack of senior obstetricians ("consultants") on the labour ward outside normal hours may lead to worse outcomes among babies born during periods of reduced cover. METHODS AND FINDINGS: We carried out a multicentre cohort study using data from 19 obstetric units in the United Kingdom between 1 April 2012 and 31 March 2013 to examine whether rates of obstetric intervention and outcome change "out-of-hours," i.e., when consultants are not providing dedicated, on-site labour ward cover. At the 19 hospitals, obstetric rotas ranged from 51 to 106 h of on-site labour ward cover per week. There were 87,501 singleton live births during the year, and 55.8% occurred out-of-hours. Women who delivered out-of-hours had slightly lower rates of intrapartum caesarean section (CS) (12.7% versus 13.4%, adjusted odds ratio [OR] 0.94; 95% confidence interval [CI] 0.90 to 0.98) and instrumental delivery (15.6% versus 17.0%, adj. OR 0.92; 95% CI 0.89 to 0.96) than women who delivered at times of on-site labour ward cover. There was some evidence that the severe perineal tear rate was reduced in out-of-hours vaginal deliveries (3.3% versus 3.6%, adj. OR 0.92; 95% CI 0.85 to 1.00). There was no evidence of a statistically significant difference between out-of-hours and "in-hours" deliveries in the rate of babies with a low Apgar score at 5 min (1.33% versus 1.25%, adjusted OR 1.07; 95% CI 0.95 to 1.21) or low cord pH (0.94% versus 0.82%; adjusted OR 1.12; 95% CI 0.96 to 1.31). Key study limitations include the potential for bias by indication, the reliance upon an organisational measure of consultant presence, and a non-random sample of maternity units. CONCLUSIONS: There was no difference in the rate of maternal and neonatal morbidity according to the presence of consultants on the labour ward, with the possible exception of a reduced rate of severe perineal tears in out-of-hours vaginal deliveries. Fewer women had operative deliveries out-of-hours. Taken together, the available evidence provides some reassurance that the current organisation of maternity care in the UK allows for good planning and risk management. However there is a need for more robust evidence on the quality of care afforded by different models of labour ward staffing.

Parity derived for pregnant women using historical administrative hospital data: accuracy varied among patient groups.

OBJECTIVES: Understanding patterns of maternity care requires knowing which women have given birth previously, but this information is typically unavailable in administrative hospital data sets. We assessed how well parity can be derived using linked historical records. STUDY DESIGN AND SETTING: Using Hospital Episode Statistics data, we identified records of women who gave birth between April 2009 and March 2010 in English National Health Service hospitals. The parity coded in these records was compared with an estimate derived from deliveries identified in previous hospital admissions between April 2000 and March 2009. RESULTS: We identified 358,849 eligible deliveries with complete parity data in the 2009-10 birth records. The historical data classified 168,041 women as multiparous; of whom, 98% were coded as multiparous in their birth record. Among 190,798 women classified as primiparous using historical data, 72% were coded as primiparous in their birth record. The proportion of accurate predictions about primiparous status from historical data varied with age, ranging from 89% for 15-18 year olds to 50% for women aged more than 35 years. CONCLUSION: Historical records in administrative hospital data sets give accurate information on multiparous status of women. There is some misclassification of primiparous status, and error rates differ among subgroups of women.

Evaluating maternity care using national administrative health datasets: how are statistics affected by the quality of data on method of delivery?

BACKGROUND: Information on maternity services is increasingly derived from national administrative health data. We evaluated how statistics on maternity care in England were affected by the completeness and consistency of data on "method of delivery" in a national dataset. METHODS: Singleton deliveries occurring between April 2009 and March 2010 in English NHS trusts were extracted from the Hospital Episode Statistics (HES) database. In HES, method of delivery can be entered twice: 1) as a procedure code in core fields, and 2) in supplementary maternity fields. We examined overall consistency of these data sources at a national level and among individual trusts. The impact of different analysis rules for handling inconsistent data was then examined using three maternity statistics: emergency caesarean section (CS) rate; third/fourth degree tear rate amongst instrumental deliveries, and elective CS rate for breech presentation. RESULTS: We identified 629,049 singleton deliveries. Method of delivery was not entered as a procedure or in the supplementary fields in 0.8% and 12.5% of records, respectively. In 545,594 records containing both data items, method of delivery was coded consistently in 96.3% (kappa = 0.93; p < 0.001). Eleven of 136 NHS trusts had comparatively poor consistency (<92%) suggesting systematic data entry errors. The different analysis rules had a small effect on the statistics at a national level but the effect could be substantial for individual NHS trusts. The elective CS rate for breech was most sensitive to the chosen analysis rule. CONCLUSIONS: Organisational maternity statistics are sensitive to inconsistencies in data on method of delivery, and publications of quality indicators should describe how such data were handled. Overall, method of delivery is coded consistently in English administrative health data.

Why are women dying when they reach hospital on time? A systematic review of the 'third delay'.

BACKGROUND: The 'three delays model' attempts to explain delays in women accessing emergency obstetric care as the result of: 1) decision-making, 2) accessing services and 3) receipt of appropriate care once a health facility is reached. The third delay, although under-researched, is likely to be a source of considerable inequity in access to emergency obstetric care in developing countries. The aim of this systematic review was to identify and categorise specific facility-level barriers to the provision of evidence-based maternal health care in developing countries. METHODS AND FINDINGS: Five electronic databases were systematically searched using a 4-way strategy that combined search terms related to: 1) maternal health care; 2) maternity units; 3) barriers, and 4) developing countries. Forty-three original research articles were eligible to be included in the review. Thirty-two barriers to the receipt of timely and appropriate obstetric care at the facility level were identified and categorised into six emerging themes (Drugs and equipment; Policy and guidelines; Human resources; Facility infrastructure; Patient-related and Referral-related). Two investigators independently recorded the frequency with which barriers relating to the third delay were reported in the literature. The most commonly cited barriers were inadequate training/skills mix (86%); drug procurement/logistics problems (65%); staff shortages (60%); lack of equipment (51%) and low staff motivation (44%). CONCLUSIONS: This review highlights how a focus on patient-side delays in the decision to seek care can conceal the fact that many health facilities in the developing world are still chronically under-resourced and unable to cope effectively with serious obstetric complications. We stress the importance of addressing supply-side barriers alongside demand-side factors if further reductions in maternal mortality are to be achieved.

The preterm birth syndrome: issues to consider in creating a classification system.

A comprehensive classification system for preterm birth requires expanded gestational boundaries that recognize the early origins of preterm parturition and emphasize fetal maturity over fetal age. Exclusion of stillbirths, pregnancy terminations, and multifetal gestations prevents comprehensive consideration of the potential causes and presentations of preterm birth. Any step in parturition (cervical softening and ripening, decidual-membrane activation, and/or myometrial contractions) may initiate preterm parturition, and should be recorded for every preterm birth, as should the condition of the mother, fetus, newborn, and placenta, before a phenotype is assigned.

The preterm birth syndrome: a prototype phenotypic classification.

Preterm birth is a syndrome with many causes and phenotypes. We propose a classification that is based on clinical phenotypes that are defined by ≥ 1 characteristics of the mother, the fetus, the placenta, the signs of parturition, and the pathway to delivery. Risk factors and mode of delivery are not included. There are 5 components in a preterm birth phenotype: (1) maternal conditions that are present before presentation for delivery, (2) fetal conditions that are present before presentation for delivery, (3) placental pathologic conditions, (4) signs of the initiation of parturition, and (5) the pathway to delivery. This system does not force any preterm birth into a predefined phenotype and allows all relevant conditions to become part of the phenotype. Needed data can be collected from the medical records to classify every preterm birth. The classification system will improve understanding of the cause and improve surveillance across populations.