Variation in elective primary cesarean delivery by patient and hospital factors

Making the cut on caesarean section: a logistic regression analysis on factors favouring caesarean sections without medical indication in comparison to spontaneous vaginal birth

BACKGROUND

In the absence of medical necessity, opting for caesarean sections exposes mothers and neonates to increased risks of enduring long-term health problems and mortality. This ultimately results in greater economic burden when compared to the outcomes of spontaneous vaginal births. In Switzerland around 33% of all births are by caesarean section. However, the rate of caesarean sections without medical indication is still unknown. Therefore, we devise an identification strategy to differentiate caesarean sections without medical indication using routine data. In addition, we aim to categorize the influencing factors for women who undergo spontaneous vaginal births as opposed to those with caesarean sections without medical indication.

METHOD

We use Swiss Federal Statistics data including 98.3% of all women giving birth from 2014 to 2018. To determine non-medically indicated caesarean sections in our dataset, we base our identification strategy on diagnosis-related groups, diagnosis codes, and procedure classifications. Subsequently, we compare characteristics of women who give birth by non-medically CS and external factors such as the density of practicing midwives to women with spontaneous vaginal birth. Logistic regression analysis measures the effect of factors, such as age, insurance class, income, or density of practicing midwives on non-medically indicated caesarean sections.

RESULTS

Around 8% of all Swiss caesarean sections have no medical indication. The regression analysis shows that higher age, supplemental insurance, higher income, and living in urban areas are associated with non-medically indicated caesarean sections, whereas a higher density of midwives decreases the likelihood of caesarean sections without medical indication.

CONCLUSIONS

By identifying non-medically indicated caesarean sections using routine data, it becomes feasible to gain insights into the characteristics of impacted mothers as well as the external factors involved. Illustrating these results, our recommendation is to revise the incentive policies directed towards healthcare professionals. Among others, future research may investigate the potential of midwife-assisted pregnancy programs on strengthening spontaneous vaginal births in absence of medical complications.

Caesarean section in uninsured women in the USA: systematic review and meta-analysis

OBJECTIVE

The aim of this study is to assess the odds of caesarean section (CS) for uninsured women in the USA and understand the underlying mechanisms as well as consequences of lower use.

STUDY DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, Embase, the Cochrane Library and CINAHL from the first year of records to April 2018.

ELIGIBILITY CRITERIA

We included studies that reported data to allow the calculation of ORs of CS of uninsured as compared with insured women.

OUTCOMES

The prespecified primary outcome was the adjusted OR of deliveries by CS of uninsured women as compared with privately or publicly insured women. The prespecified secondary outcome was the crude OR of deliveries by CS of uninsured women as compared with insured women.

RESULTS

12 articles describing 16 separate studies involving more than 8.8 million women were included in this study. We found: 0.70 times lower odds of CS in uninsured as compared with privately insured women (95% CI 0.63 to 0.78), with no relevant heterogeneity between studies (τ2=0.01); and 0.92 times lower odds for CS in uninsured as compared with publicly insured women (95% CI 0.80 to 1.07), with no relevant heterogeneity between studies (τ2=0.02). We found 0.70 times lower odds in uninsured as compared with privately and publicly insured women (95% CI 0.69 to 0.72).

CONCLUSIONS

CSs are less likely to be performed in uninsured women as compared with insured women. While the higher rates for CS among privately insured women can be explained with financial incentives associated with private insurance, the lower odds among uninsured women draw attention at barriers to access for delivery care. In many regions, the rates for uninsured women are above, close or below the benchmarks for appropriate CS rates and could imply both, underuse and overuse.

Predictive modeling of emergency cesarean delivery

OBJECTIVE

To increase discriminatory accuracy (DA) for emergency cesarean sections (ECSs).

STUDY DESIGN

We prospectively collected data on and studied all 6,157 births occurring in 2014 at four public hospitals located in three different autonomous communities of Spain. To identify risk factors (RFs) for ECS, we used likelihood ratios and logistic regression, fitted a classification tree (CTREE), and analyzed a random forest model (RFM). We used the areas under the receiver-operating-characteristic (ROC) curves (AUCs) to assess their DA.

RESULTS

The magnitude of the LR+ for all putative individual RFs and ORs in the logistic regression models was low to moderate. Except for parity, all putative RFs were positively associated with ECS, including hospital fixed-effects and night-shift delivery. The DA of all logistic models ranged from 0.74 to 0.81. The most relevant RFs (pH, induction, and previous C-section) in the CTREEs showed the highest ORs in the logistic models. The DA of the RFM and its most relevant interaction terms was even higher (AUC = 0.94; 95% CI: 0.93-0.95).

CONCLUSION

Putative fetal, maternal, and contextual RFs alone fail to achieve reasonable DA for ECS. It is the combination of these RFs and the interactions between them at each hospital that make it possible to improve the DA for the type of delivery and tailor interventions through prediction to improve the appropriateness of ECS indications.

Caesarean sections and private insurance: systematic review and meta-analysis

OBJECTIVE

Financial incentives associated with private insurance may encourage healthcare providers to perform more caesarean sections. We therefore sought to determine the association of private insurance and odds of caesarean section.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

MEDLINE, Embase and The Cochrane Library from the first year of records through August 2016.

ELIGIBILITY CRITERIA

We included studies that reported data to allow the calculation of OR of caesarean section of privately insured as compared with publicly insured women.

OUTCOMES

The prespecified primary outcome was the adjusted OR of births delivered by caesarean section of women covered with private insurance as compared with women covered with public insurance. The prespecified secondary outcome was the crude OR of births delivered by caesarean section of women covered with private insurance as compared with women covered with public insurance.

RESULTS

Eighteen articles describing 21 separate studies in 12.9 million women were included in this study. In a meta-analysis of 13 studies, the adjusted odds of delivery by caesarean section was 1.13 higher among privately insured women as compared with women with public insurance coverage (95% CI 1.07 to 1.18) with no relevant heterogeneity between studies (τ²=0.006). The meta-analysis of crude estimates from 12 studies revealed a somewhat more pronounced association (pooled OR 1.35, 95% CI 1.27 to 1.44) with no relevant heterogeneity between studies (τ²=0.011).

CONCLUSIONS

Caesarean sections are more likely to be performed in privately insured women as compared with women using public health insurance coverage. Although this effect is small on average and variable in its magnitude, it is present in all analyses we performed.

Labor and Delivery Experiences of Mothers with Suspected Large Babies

OBJECTIVE

To characterize the prevalence of and factors associated with clinicians' prenatal suspicion of a large baby; and to determine whether communicating fetal size concerns to patients was associated with labor and delivery interventions and outcomes.

METHODS

We examined data from women without a prior cesarean who responded to Listening to Mothers III, a nationally representative survey of women who had given birth between July 2011 and June 2012 (n = 1960). We estimated the effect of having a suspected large baby (SLB) on the odds of six labor and delivery outcomes.

RESULTS

Nearly one-third (31.2%) of women were told by their maternity care providers that their babies might be getting "quite large"; however, only 9.9% delivered a baby weighing ≥4000 g (19.7% among mothers with SLBs, 5.5% without). Women with SLBs had increased adjusted odds of medically-induced labor (AOR 1.9; 95% CI 1.4-2.6), attempted self-induced labor (AOR 1.9; 95% CI 1.4-2.7), and use of epidural analgesics (AOR 2.0; 95% CI 1.4-2.9). No differences were noted for overall cesarean rates, although women with SLBs were more likely to ask for (AOR 4.6; 95% CI 2.8-7.6) and have planned (AOR 1.8; 95% CI 1.0-4.5) cesarean deliveries. These associations were not affected by adjustment for gestational age and birthweight.

CONCLUSIONS FOR PRACTICE

Only one in five US women who were told that their babies might be getting quite large actually delivered infants weighing ≥4000 g. However, the suspicion of a large baby was associated with an increase in perinatal interventions, regardless of actual fetal size.

Intrapartum cesarean delivery in nulliparas: risk factors compared by two analytical approaches

OBJECTIVE

To determine risk factors for cesarean delivery in nulliparas at labor admission.

STUDY DESIGN

Nulliparas with live-born, singleton gestations ⩾37 weeks in spontaneous or induced labor were analyzed from the Consortium on Safe Labor database in a retrospective observational study. Classification and regression tree (CART) and multivariate logistic regression analysis determined risk factors for cesarean delivery.

RESULT

Of the 66 539 nulliparas, 22% had a cesarean delivery. In the CART analysis, the first cervical dilation exam was the first branch followed by body mass index (BMI). Cesarean deliveries occurred in 45%, 25%, 14% and 10% of deliveries at <1, 1 to 3, 4 and ⩾5 cm dilated, respectively. The BMI influence was most evident in the <1 cm dilation category with 26% of BMI <25 kg m(-2) and 66% of BMI ⩾40 kg m(-2) having a cesarean delivery. The fewest cesarean deliveries (5%) occurred in those ⩾5 cm and BMI <25 kg m(-2). In the multivariate regression analysis, first cervical dilation exam <1 cm (odds ratio (OR) 5.1, 95% confidence interval (CI): 4.5 to 5.7; reference ⩾5 cm) and BMI ⩾40 kg m(-2) (OR 5.1, 95% CI: 4.6 to 5.7; reference BMI <25.0 kg m(-2)) had the highest odds for cesarean delivery.

CONCLUSION

Cervical dilation on admission followed by BMI were the two most important risk factors for cesarean delivery identified in both CART and multivariate regression analysis.

Mode of delivery and outcomes by birth weight among spontaneous and induced singleton cephalic nulliparous labors

OBJECTIVE

To assess the effect of birth weight on mode of delivery among nulliparous women in a setting with no policy of elective induction for suspected macrosomia.

METHODS

In an observational study, data were assessed from nulliparous women with a single cephalic pregnancy of at least 37 weeks in spontaneous (Robson group 1) and induced (Robson group 2a) labor attending a hospital in Dublin, Ireland, between January 1, 2008, and December 31, 2009. The primary outcome measure was mode of delivery.

RESULTS

A total of 7528 nulliparous labors were included (4989 in group 1 and 2539 in group 2a). The cesarean section rate was 15.1% overall (n=1139), with 411 (8.2%) in group 1, and 728 (28.7%) in group 2a. Cesarean delivery rates rose with increasing birth weight in group 1, from 119 (6.3%) of 1886 infants weighing 3000-3499 g and 160 (8.5%) of 1892 weighing 3500-3999 g, to 19 (26.8%) of 71 weighing 4500-4999 g. Rates of cesarean delivery were significantly higher in induced labor (group 2a) for each birth-weight category, ranging from 202 (25.9%) of 781 weighing 3000-3499 g and 243 (27.0%) of 899 weighing 3500-3999 g, to 38 (48.1%) of 79 weighing 4500-4999 g (P<0.01 for all).

CONCLUSION

In a setting with standardized management of labor, birth weight remains a significant determinant of mode of delivery.

Public hospital quality report awareness: evidence from National and Californian Internet searches and social media mentions, 2012

OBJECTIVES

Publicly available hospital quality reports seek to inform consumers of important healthcare quality and affordability attributes, and may inform consumer decision-making. To understand how much consumers search for such information online on one Internet search engine, whether they mention such information in social media and how positively they view this information.

SETTING AND DESIGN

A leading Internet search engine (Google) was the main focus of the study. Google Trends and Google Adwords keyword analyses were performed for national and Californian searches between 1 August 2012 and 31 July 2013 for keywords related to 'top hospital', best hospital', and 'hospital quality', as well as for six specific hospital quality reports. Separately, a proprietary social media monitoring tool was used to investigate blog, forum, social media and traditional media mentions of, and sentiment towards, major public reports of hospital quality in California in 2012.

PRIMARY OUTCOME MEASURES

(1) Counts of searches for keywords performed on Google; (2) counts of and (3) sentiment of mentions of public reports on social media.

RESULTS

National Google search volume for 75 hospital quality-related terms averaged 610 700 searches per month with strong variation by keyword and by state. A commercial report (Healthgrades) was more commonly searched for nationally on Google than the federal government's Hospital Compare, which otherwise dominated quality-related search terms. Social media references in California to quality reports were generally few, and commercially produced hospital quality reports were more widely mentioned than state (Office of Statewide Healthcare Planning and Development (OSHPD)), or non-profit (CalHospitalCompare) reports.

CONCLUSIONS

Consumers are somewhat aware of hospital quality based on Internet search activity and social media disclosures. Public stakeholders may be able to broaden their quality dissemination initiatives by advertising on Google or Twitter and using social media interactively with consumers looking for relevant information.

National trends in primary cesarean delivery, labor attempts, and labor success, 1990-2010

OBJECTIVE

The national primary cesarean delivery rate increased until 2004, but after 2004, this rate cannot be tracked using Vital Statistics data. Additionally, it is unknown whether changes in the primary cesarean delivery rate reflect changes in the rate of labor attempts, labor success, or both. Here, using hospital discharge data, we examined national trends in primary cesarean deliveries, labor attempts, and labor success among women without prior cesarean delivery between 1990 and 2010.

STUDY DESIGN

This analysis of serial cross-sectional data from the National Hospital Discharge Survey used Joinpoint regression to assess trends over time and logistic regression with marginal effects to identify rates of change over time and adjust for demographic and clinical factors.

RESULTS

The primary cesarean delivery rate declined 0.2 percentage points per year (95% confidence interval [CI], 0.1-0.3) between 1990 and 1999, increased 1.0 percentage point per year (95% CI, 0.8-1.2) between 1999 and 2004, and increased 0.3 percentage points (95% CI, 0.1-0.6) per year from 2004 until 2010. Between 1998 and 2005, the rate of labor attempts declined 0.4 percentage points (95% CI, 0.3-0.5) per year. No changes in the labor attempt rate occurred between 2005 and 2010. Labor success rates increased 0.2 percentage points (95% CI, 0.1-0.3) per year between 1990 and 1998 but then declined 0.5 (95% CI, 0.5-0.8) percentage points per year from 1998 to 2010. Adjusted results were similar.

CONCLUSION

The primary cesarean delivery rate continued to increase after 2004. Increases in the primary cesarean delivery rate after 2005 were driven by declines in labor success rates.

Risk adjustment for cesarean delivery rates: how many variables do we need? An observational study using administrative databases

Background

Various studies indicate that inter-hospital comparisons have to take case mix into account and that risk adjustment procedures are necessary to control for potential predictors of cesarean delivery (CD). Different data sources have been used to retrieve information on potential predictors of CD. The aim of this study was to compare the discrimination capacity and fit of predictive models of CD created using different sources and to assess whether more complex models improve inter-hospital comparisons.

Methods

We created 4 predictive models of CD. One model included only variables from Hospital Discharge Records of the index hospitalization, one included also information from previous hospitalizations, one also clinical variables from birth certificates (BC) and one also socio-demographic variables. We compared the four models using the Receiver Operator Curve and the Akaike and Bayesian Information Criteria.

Results

Information from Birth Certificates improved the discrimination and model fit. Adding socio-demographic variables or past comorbidities did not improve the discrimination capacity or the model fit. Hospital-specific CD resulting from the models were highly correlated.

Conclusions

Record linkage improves the performance of the models but does not affect inter-hospital comparisons.

Impact of non-clinical factors on primary cesarean deliveries

The patient characteristics that influence cesarean rates are well known. However, there are many non clinical factors that also influence cesarean rates. Understanding these non clinical factors and how they can be changed to improve care is an important part of obstetrics. Provider staffing patterns, the types of providers and how information can be used to effectively change practice patterns are explored in this article.

Risk adjustment models for interhospital comparison of CS rates using Robson's ten group classification system and other socio-demographic and clinical variables

Background

Caesarean section (CS) rate is a quality of health care indicator frequently used at national and international level. The aim of this study was to assess whether adjustment for Robson’s Ten Group Classification System (TGCS), and clinical and socio-demographic variables of the mother and the fetus is necessary for inter-hospital comparisons of CS rates.

Methods

The study population includes 64,423 deliveries in Emilia-Romagna between January 1, 2003 and December 31, 2004, classified according to theTGCS. Poisson regression was used to estimate crude and adjusted hospital relative risks of CS compared to a reference category. Analyses were carried out in the overall population and separately according to the Robson groups (groups I, II, III, IV and V–X combined). Adjusted relative risks (RR) of CS were estimated using two risk-adjustment models; the first (M1) including the TGCS group as the only adjustment factor; the second (M2) including in addition demographic and clinical confounders identified using a stepwise selection procedure. Percentage variations between crude and adjusted RRs by hospital were calculated to evaluate the confounding effect of covariates.

Results

The percentage variations from crude to adjusted RR proved to be similar in M1 and M2 model. However, stratified analyses by Robson’s classification groups showed that residual confounding for clinical and demographic variables was present in groups I (nulliparous, single, cephalic, ≥37 weeks, spontaneous labour) and III (multiparous, excluding previous CS, single, cephalic, ≥37 weeks, spontaneous labour) and IV (multiparous, excluding previous CS, single, cephalic, ≥37 weeks, induced or CS before labour) and to a minor extent in groups II (nulliparous, single, cephalic, ≥37 weeks, induced or CS before labour) and IV (multiparous, excluding previous CS, single, cephalic, ≥37 weeks, induced or CS before labour).

Conclusions

The TGCS classification is useful for inter-hospital comparison of CS section rates, but residual confounding is present in the TGCS strata.

Association between type of health insurance and elective cesarean deliveries: New Jersey, 2004-2007

OBJECTIVES

I examined the relationship between insurance coverage, which may influence physician incentives and maternal choices, and cesarean delivery before labor.

METHODS

I analyzed hospital discharge data for mothers without previous cesarean deliveries in New Jersey between 2004 and 2007, with adjustment for maternal age, race, marital status, and maternal, fetal, and placental conditions.

RESULTS

Nearly 1 in 7 women (13.9%) had a cesarean delivery without laboring. Insurance status was strongly associated with cesarean birth. Women insured by Medicaid (adjusted relative risk [ARR] = 0.88; 95% confidence interval [CI] = 0.84, 0.91) or self-paying (ARR = 0.81; 95% CI = 0.78, 0.85) had a significantly lower likelihood, and women insured by BlueCross (ARR = 1.06; 95% CI = 1.03, 1.09) or standard commercial plans (ARR = 1.06; 95% CI = 1.02, 1.10) had a significantly higher likelihood of cesarean delivery than did women insured by commercial health maintenance organizations. These associations persisted in subsets restricted to lower-risk women and in qualitative sensitivity analyses for a hypothetical single, binary, unmeasured confounder.

CONCLUSIONS

Insurance status has a small, independent impact on whether a woman without a previous cesarean delivery proceeds to labor or has a cesarean delivery without labor.

Scheduled cesarean delivery: maternal and neonatal risks in primiparous women in a community hospital setting

We compared the short-term maternal and neonatal outcomes of women who deliver by cesarean without labor compared with women who deliver by cesarean after labor or by vaginal birth. This was a retrospective cohort study of women delivering a first baby from 1998 to 2002. Hospital discharge diagnostic coding identified unlabored cesarean deliveries (UCDs), labored cesarean deliveries (LCDs), and vaginal births (VBs). Medical records were abstracted and mode of delivery confirmed. The three outcomes of interest were maternal bleeding complications, maternal febrile morbidity, and neonatal respiratory complications. Using logistic regression for each outcome, we investigated whether mode of delivery was associated with the outcome, independent of other factors. The study groups included 513 UCDs, 261 LCDs, and 251 VBs. Compared with the UCD group, the adjusted odds of bleeding complications was higher in the LCD comparison group (odds ratio [OR] 2.3; 95% confidence interval [CI] 1.21, 4.53) and the VB comparison group (OR 1.96; 95% CI 0.95, 4.02). The incidence of febrile morbidity was similar for both cesarean groups but lower in the VB group. Both comparison groups had lower odds of neonatal complications than the UCD group (OR for LCD comparison group 0.52; 95% CI 0.27, 0.95 and OR for VB comparison group 0.26; 95% CI 0.098, 0.59). Scheduled cesarean is associated with increased odds of neonatal respiratory complications but decreased odds of maternal bleeding complications.

Primary cesarean delivery among parous women in the United States, 1990-2003

OBJECTIVE

To explore trends in primary cesarean delivery rates among parous women with singleton pregnancies in the United States between 1990 and 2003.

METHODS

The analysis used data from national birth files based on U.S. birth certificates between 1990 and 2003. The primary cesarean delivery rate was defined as the number of primary cesarean deliveries per 100 deliveries among parous women with singleton pregnancies who have not had a previous cesarean delivery. A stratified analysis was employed to investigate whether trends varied by maternal age, gestational age, race/ethnicity, or region.

RESULTS

In the United States, the primary cesarean delivery rate among parous women decreased modestly from 7.1% in 1990 to 6.6% in 1996 but increased progressively to 9.3% in 2003. The increase in cesarean rates from 1996 to 2003 varied substantially by race/ethnicity: Hispanic and non-Hispanic white women exhibited lower and similar rates, whereas rates for non-Hispanic black women were consistently higher and rose by a far greater extent across the years. There were substantial differences in cesarean delivery trends across geographic divisions, with greatest increases observed in the mid-Atlantic, South Central, and South Atlantic areas of the United States. Primary cesarean rates also declined considerably with increasing gestational age.

CONCLUSION

Similar to the overall cesarean delivery rate, primary cesarean rates among parous women with singleton pregnancies have increased substantially in the United States since 1996.

LEVEL OF EVIDENCE

III.

Nulliparous term singleton vertex cesarean delivery rates: institutional and individual level predictors

OBJECTIVE

This study was undertaken to determine individual and institutional level variables predictive of variations in nulliparous term singleton vertex cesarean delivery rates.

STUDY DESIGN

Retrospective cohort study of 28,863 nulliparous term singleton vertex births at 40 Arizona hospitals.

RESULTS

The average nulliparous term singleton vertex cesarean delivery rate was 22.0%, the lowest hospital rate was 10.3%, high, 34.2%. The following individual level variables increased the nulliparous term singleton vertex cesarean delivery rate in a multivariable model: increased mother's age, African American race, increased birthweight, labor induction, and the presence of medical conditions such as diabetes and hypertension. Of the institutional variables, after adjustment, the highest level of nursery or a higher percentage of government-paid births was associated with lower risks, whereas delivery at a hospital with the lowest level of care or with an obstetric and gynecology residency was associated with an increased risk of cesarean delivery.

CONCLUSION

Substantial variations in nulliparous term singleton vertex cesarean delivery rates were seen in this comparative analysis of 40 hospitals.

Gestational pyelonephritis as an indicator of the quality of ambulatory maternal health care services

OBJECTIVE

Inpatient conditions that might be avoided through improved outpatient services are called Ambulatory Care Sensitive Indicators, and they include pyelonephritis in nonpregnant adults. No such indicators have been developed for pregnant women. We examine whether hospital-specific rates of gestational pyelonephritis may serve as a measure of the quality of ambulatory maternal care.

METHODS

The California Department of Health Services provided an administrative data set linking maternal and newborn delivery records for 1997 with antepartum hospital admissions. We created a "low-risk" study population by largely excluding women with maternal, fetal, and placental morbidities and those with no first-trimester prenatal care. We generated hospital-specific infection rates using a Bayesian hierarchical logistic regression model.

RESULTS

We identified 280,816 low-risk women, of whom 1,853 (0.66%) had at least 1 inpatient admission for gestational pyelonephritis. The model suggested only 2 risk factors: MediCal as a payer (odds ratio 1.60, 95% confidence interval 1.46-1.80 compared with all other payers), and African-American race (odds ratio 1.24, 95% confidence interval 1.10-1.41 compared with white race). Women with pyelonephritis were more than twice as likely to deliver preterm. Adjusted rates of gestational pyelonephritis for the 291 hospitals in the sample ranged from 0.22% to 2.64%.

CONCLUSION

These findings suggest that because of its preventability, its consequent related morbidity, and the variation in hospital-specific rates, gestational pyelonephritis meets both clinical and technical requirements as a quality indicator for ambulatory maternal care. The use of such rates would provide an opportunity for hospitals to improve patient outcomes through partnership with obstetricians in the management of women at risk.

LEVEL OF EVIDENCE

II-3.

Using clinical classification trees to identify individuals at risk of STDs during pregnancy

CONTEXT

Few studies have used classification tree analysis to produce empirically driven decision tools that identify subgroups of women at risk of STDs during pregnancy. Such tools can guide care, treatment and prevention efforts in clinical settings.

METHODS

A sample of 647 women aged 14-25 attending two urban obstetrics and gynecology clinics in 2001-2004 were surveyed in their second and third trimesters. Baseline predictors at the individual, dyad, and family and community levels were used to develop a classification tree that differentiated subgroups of women by STD incidence at 35 weeks' gestation. Logistic regression analyses were conducted to assess whether the classification tree groups or commonly used risk factors better predicted STD incidence.

RESULTS

Nineteen percent of women had an incident STD during pregnancy. Classification tree analysis identified three subgroups with a high STD incidence (33-61%), one with a moderate incidence (16%) and three with a low incidence (6-11%). Women in subgroups with high STD incidence included those not living with the partner with whom they conceived and those who had a moderate or a high level of depression, a history of STDs and a low level of social support. A logistic regression model using groups defined by the classification tree analysis had better predictive ability than one using common demographic and sexual risk predictors.

CONCLUSION

This classification tree identified risk factors not captured by traditional risk screenings, and could be used to guide STD treatment, care and prevention within the prenatal care setting.

Primary Cesarean Deliveries Prior to Labor in the United States, 1979–2004

OBJECTIVES

To provide for the United States yearly estimates of first-time (primary) cesareans prior to labor and to examine factors associated with 1979-2004 trends.

METHODS

We estimated the annual percent of total, primary, and repeat cesareans with and without labor for 15- to 44-year-old women with live births in the 1979-2004 National Hospital Discharge Survey (NHDS; N=706,062). For women without prior cesareans (N=628,064), we used logistic regression to examine whether trends in primary cesarean before labor are explained by changes over time in: (1) the frequency of pregnancy complications, women's age, principal source of payment for delivery, hospital ownership, size, and region; and (2) the decision to deliver by cesarean when complications are present.

RESULTS

Annually 4.5-6.6% of women delivered by primary cesarean prior to labor in 1979-2004. Recently, there has been a rise. An increase in reported pregnancy complications contributed to more primary cesareans before labor in 1979-2004. Changes in women's age, principal payment source, and hospital characteristics do not explain 1979-2004 trends. Changes in delivery practices with respect to seven complications increased primary cesareans before labor in the 1980s.

CONCLUSIONS

From 1979 to 2004, primary cesareans before labor contributed less to total cesareans than primary cesareans during labor and repeat cesareans without labor. Since 1998, primary cesareans pre-labor have increased less than previously reported. The recent increase is not explained by changes in the frequency of pregnancy complications, women's age, insurance, or delivery hospital characteristics. Changes in delivery practices regarding pregnancy complications may have contributed to the recent increase.

Modeling low birth weights using threshold regression: results for U.S. birth data

Babies born live under 2,500 g or with a gestational age under 37 weeks are often inadequately developed and have elevated risks of infant mortality, congenital malformations, mental retardation, and other physical and neurological impairments. In this paper, we model birth weight as a first hitting time (FHT) of a birthing boundary in a Wiener process representing fetal development. We associate the parameters of the process and boundary with covariates describing maternal characteristics and the birthing environment using a relatively new regression methodology called threshold regression. Two FHT models for birth weight are developed. One is a mixture model and the other a competing risks model. These models are tested in a case demonstration using a 4%-systematic sample of the more than four million live births in the United States in 2002. An extensive data set for these births was provided by the National Center for Health Statistics. The focus of this paper is on the conceptual framework, models and methodology. A full empirical study is deferred to a later occasion.

Mothers’ and fathers’ lateral biases for holding their newborn infants: A study of images from the World Wide Web

Photographic and direct-observation studies show that most adults hold infants on the left side. This basic directional effect is well established, but other details are still uncorroborated, uncertain, or inconsistent across studies. These include the overall strength of the bias, the role of the sex, parental status, and experience of the holder, and the sex and age of the infant. Given their importance for understanding the bias, we sought further information from a large sample of photographs of mothers and fathers, some of them first-time parents, others not, holding their infants in the first minutes, hours, or days after birth. The results confirmed the basic directional effect and provided information on the other variables. They also raise questions for further research, especially as it pertains to the use of photographs vs direct observation.

Risk adjustment for inter-hospital comparison of primary cesarean section rates: need, validity and parsimony

BACKGROUND

Cesarean section rates is often used as an indicator of quality of care in maternity hospitals. The assumption is that lower rates reflect in developed countries more appropriate clinical practice and general better performances. Hospitals are thus often ranked on the basis of caesarean section rates. The aim of this study is to assess whether the adjustment for clinical and sociodemographic variables of the mother and the fetus is necessary for inter-hospital comparisons of cesarean section (c-section) rates and to assess whether a risk adjustment model based on a limited number of variables could be identified and used.

METHODS

Discharge abstracts of labouring women without prior cesarean were linked with abstracts of newborns discharged from 29 hospitals of the Emilia-Romagna Region (Italy) from 2003 to 2004. Adjusted ORs of cesarean by hospital were estimated by using two logistic regression models: 1) a full model including the potential confounders selected by a backward procedure; 2) a parsimonious model including only actual confounders identified by the "change-in-estimate" procedure. Hospital rankings, based on ORs were examined.

RESULTS

24 risk factors for c-section were included in the full model and 7 (marital status, maternal age, infant weight, fetopelvic disproportion, eclampsia or pre-eclampsia, placenta previa/abruptio placentae, malposition/malpresentation) in the parsimonious model. Hospital ranking using the adjusted ORs from both models was different from that obtained using the crude ORs. The correlation between the rankings of the two models was 0.92. The crude ORs were smaller than ORs adjusted by both models, with the parsimonious ones producing more precise estimates.

CONCLUSION

Risk adjustment is necessary to compare hospital c-section rates, it shows differences in rankings and highlights inappropriateness of some hospitals. By adjusting for only actual confounders valid and more precise estimates could be obtained.

Maternal risk profiles and the primary cesarean rate in the United States, 1991-2002

OBJECTIVES

We examined factors contributing to shifts in primary cesarean rates in the United States between 1991 and 2002.

METHODS

US national birth certificate data were used to assess changes in primary cesarean rates stratified according to maternal age, parity, and race/ethnicity. Trends in the occurrence of medical risk factors or complications of labor or delivery listed on birth certificates and the corresponding primary cesarean rates for such conditions were examined.

RESULTS

More than half (53%) of the recent increase in overall cesarean rates resulted from rising primary cesarean rates. There was a steady decrease in the primary cesarean rate from 1991 to 1996, followed by a rapid increase from 1996 to 2002. In 2002, more than one fourth of first-time mothers delivered their infants via cesarean. Changing primary cesarean rates were not related to general shifts in mothers' medical risk profiles. However, rates for virtually every condition listed on birth certificates shifted in the same pattern as with the overall rates.

CONCLUSIONS

Our results showed that shifts in primary cesarean rates during the study period were not related to shifts in maternal risk profiles.

A Framework for the Development of MaternalQuality of Care Indicators

BACKGROUND

In collaboration with the California Department of Health Maternal and Child Health Branch, the authors formed a Working Group to identify potential clinical indicators that could be used to inform decision making regarding maternal health care quality.

OBJECTIVE

To develop potential indicators for the assessment of maternal health care quality.

MATERIALS AND METHODS

A Working Group was convened to review information from the published literature and expert opinion. Selection of potential indicators was guided by the following goals: 1) To identify key areas for routine aggregate monitoring; 2) To include perspectives of relevant stakeholders in maternal health care services; 3) To include measures that are comprehensive and reflect a balance between maternal and fetal interests; and 4) To develop measures that would be valid, generalizable, mutable, and feasible.

RESULTS

Ninety potential indicators were identified. Each underwent a thorough review based on: its definition, objective, and validity; its contribution to innovation; the cost and timeliness of implementation; its feasibility, acceptability, and potential effectiveness; and its compatibility with ethics, values, and social policy. This process yielded 24 final indicators from the following categories: Health Status and Access (e.g., availability of 24 h inpatient anesthesia); Preconception and Interconception Care (e.g., Pap smear use); Antenatal Care (e.g., hospitalization for uncontrolled diabetes or pyelonephritis); Labor and Delivery Care (e.g., chorioamnionitis or obstetrical hemorrhage), and Postpartum Care (e.g., rate of postpartum visits).

CONCLUSIONS

These potential indicators, representative of the women's health continuum, can serve as a foundation to structure the development of consensus and methods for maternal health care quality assessment.

Hospital Rates of Maternal and Neonatal Infection in a Low-Risk Population

BACKGROUND

In 2003, the Agency for Healthcare Quality and Research (AHRQ) published its Quality Indicators for healthcare, and set out methodological criteria for the evaluation of potential candidates.

OBJECTIVES

Because perinatal infections may result from poor obstetrical practices, we intended to describe the variability of maternal and congenital neonatal infections across different types of hospital ownership (e.g., not for profit, government), and to assess whether rates of these infections meet criteria as quality indicators.

RESEARCH DESIGN

Population-based cohort study.

SUBJECTS

All laboring women without maternal, fetal, or placental complications who delivered in California in 1997, and their neonates, as reported through hospital discharge data.

MEASURES

A Bayesian hierarchical logistic regression model was used to quantify the effects of both "patient-level" risk factors such as parity and prior cesarean history, and "hospital-level" risk factors such as ownership and teaching status.

RESULTS

The 308,841 mother-newborn pairs in this low-risk study population delivered at 281 hospitals; 0.39% had uterine infections and 1.3% had neonatal infections. Hospital ownership and teaching status were strongly associated with perinatal infection. Secondly, methods used to estimate and analyze hospital-specific infection rates identified hospitals with exceptionally high rates. Twenty-eight hospitals had neonatal infection rates that ranged from 3% to 28%.

CONCLUSIONS

The methods presented here were consistent with AHRQ methods and criteria for potential Quality Indicators. They also identified hospitals with exceptionally high rates of infectious morbidity. The relationship between hospital ownership and obstetrical practice patterns, and the feasibility of practice improvement, remain to be studied.

Secular trends in cesarean delivery rates among macrosomic deliveries in the United States, 1989 to 2002

OBJECTIVES

We describe national trends in cesarean delivery rates among macrosomic infants during 1989 to 2000 and evaluate the maternal characteristics and risk factors for macrosomic infants delivered by cesarean section as compared to macrosomic infants delivered vaginally.

STUDY DESIGN

We analyzed US 1989 to 2000 Natality files, selecting term (37 to 44 week) single live births to U.S. resident mothers. We compare macrosomic infants (4000 to 4499, 4500 to 4999 and 5000+ g infants) to a normosomic (3000 to 3999 g) control group.

RESULTS

The proportion of cesarean deliveries among 5000+ g infants increased significantly over the time period. The adjusted odds ratio of cesarean delivery increased for all macrosomic categories over the 12-year period, as compared to normal birth weight infants.

CONCLUSIONS

Rates of cesarean delivery among macrosomic infants continue to increase despite a lack of evidence of the benefits of cesarean delivery within this population. Further exploration of the rationale for this trend is warranted and should include the development of an optimal delivery strategy for such patients.

Suspicion and treatment of the macrosomic fetus: a review

OBJECTIVE

To review the prevalence of and our ability to identify macrosomic (birthweight >4000 g) fetuses. Additionally, based on the current evidence, propose an algorithm for treatment of suspected macrosomia.

STUDY DESIGN

A review.

RESULTS

According to the National Vital Statistics, in the United States, the prevalence of newborns weighing at least 4000 g has decreased by 10% in seven years (10.2% in 1996 and 9.2% in 2002) and 19% for newborns with weights >5000 g (0.16% and 0.13%, respectively). Bayesian calculations indicates that the posttest probability of detecting a macrosomic fetus in an uncomplicated pregnancy is variable, ranging from 15% to 79% with sonographic estimates of birth weight, and 40 to 52% with clinical estimates. Among diabetic patients the post-test probability of identifying a newborn weighing >4000 g clinically and sonographically is over 60%. Among uncomplicated pregnancies, there is sufficient evidence that suspected macrosomia is not an indication for induction or for primary cesarean delivery. For pregnancies complicated by diabetes, with a prior cesarean delivery or shoulder dystocia, delivery of a macrosomic fetus increases the rate of complications, but there is insufficient evidence about the threshold of estimated fetal weight that should prompt cesarean delivery.

CONCLUSION

Due to the inaccuracies, among uncomplicated pregnancies suspicion of macrosomia is not an indication for induction or for primary cesarean delivery.

Rethinking the cesarean rate: how pregnancy complications may affect interhospital comparisons

BACKGROUND

The cesarean rate has served an integral role in the monitoring of obstetrical care, and in 2002, the national rate reached 26.1%, the highest ever reported.

OBJECTIVE

We sought to describe the effect of clinical complications on hospital cesarean rates.

RESEARCH DESIGN

This was a population-based cohort study.

SUBJECTS

All laboring women without a previous cesarean who delivered in California in 1995 as reported through public-use hospital discharge data were included.

MEASURES

Women with and without maternal, fetal, or placental complications were compared with respect to cesarean use. Using recursive partitioning algorithms, women with complications were stratified into clinically homogeneous categories, which were analyzed separately with respect to cesarean use.

RESULTS

The 443,532 women delivered at 288 hospitals and included 116,170 women (26.2%) in the complicated group (cesarean rate 22.6%); and 327,362 women (73.8%) in the uncomplicated group (cesarean rate 6.7%). At the hospital level, the cesarean rates among the complicated and uncomplicated patients respectively were: median 23.5% (range, 2.2-9.9%); and median 6.5% (range, 1.8-18.2%). Recursive partitioning algorithms suggested 16 distinct clinical categories, with cesarean rates varying from 8.9% for women with asthma to 84.5% for women with an unengaged fetal head.

CONCLUSIONS

Cesarean rates varied widely across complication types, and complication-specific rates varied widely among hospitals. Although the presence of pregnancy complications upon hospital admission comprised the strongest factor affecting first-time cesarean use among laboring women, the importance and interdependence of these clinical conditions has yet to be incorporated into commonly used models for cesarean rate comparisons.

Classification and regression tree analysis in public health: methodological review and comparison with logistic regression

BACKGROUND

Audience segmentation strategies are of increasing interest to public health professionals who wish to identify easily defined, mutually exclusive population subgroups whose members share similar characteristics that help determine participation in a health-related behavior as a basis for targeted interventions. Classification and regression tree (C&RT) analysis is a nonparametric decision tree methodology that has the ability to efficiently segment populations into meaningful subgroups. However, it is not commonly used in public health.

PURPOSE

This study provides a methodological overview of C&RT analysis for persons unfamiliar with the procedure.

METHODS AND RESULTS

An example of a C&RT analysis is provided and interpretation of results is discussed. Results are validated with those obtained from a logistic regression model that was created to replicate the C&RT findings. Results obtained from the example C&RT analysis are also compared to those obtained from a common approach to logistic regression, the stepwise selection procedure. Issues to consider when deciding whether to use C&RT are discussed, and situations in which C&RT may and may not be beneficial are described.

CONCLUSIONS

C&RT is a promising research tool for the identification of at-risk populations in public health research and outreach.

Elective primary caesarean delivery: accuracy of administrative data

The caesarean delivery rate has become a commonly used measure intended to reflect the quality of obstetric care. At least 25% of all primary caesarean deliveries occur electively, i.e. to women who are not in labour. This study is intended to validate a previously published model designed to use ICD-9-CM codes to identify and categorise cases of elective primary caesarean delivery by their indication. ICD-9-CM codes were compared with diagnoses written in the medical record for all women without a prior caesarean who delivered in the same month in a single hospital to examine the accuracy of the codes for 12 potential elective primary caesarean indications derived by the published model: malpresentation; bleeding; genital herpes; severe hypertension; uterine scar; multiple gestation; macrosomia; unengaged fetus; maternal soft tissue conditions; other hypertensive conditions; prematurity; and chromosomal anomalies. Of 440 eligible women, a total of 26 (5.9%) had an elective primary caesarean by medical record review vs. [27] (6.1%) by administrative data. Using medical record data as the gold standard, the sensitivity, specificity, and accuracy of administrative data for the identification of elective primary caesarean delivery were 73.1%, 98.1%, and 96.6%, respectively. Administrative coding for all of the 12 conditions was highly specific, although wide variability existed in its sensitivity; its accuracy ranged between 83.9% and 100%. These results suggest that, despite widespread use of caesarean delivery rates obtained through administrative data, more experience is needed to determine which obstetric codes may be sufficiently specific, sensitive, or prevalent to serve a monitoring or surveillance function reflecting the quality of obstetrical care. The results support continued efforts to use administrative data to monitor elective primary caesarean delivery.

Tertiary care improves the chance for vaginal delivery in women with preeclampsia

OBJECTIVE

The purpose of this study was to determine whether the level of hospital care affects cesarean delivery rates for women with preeclampsia.

STUDY DESIGN

We conducted a population-based cohort study using Missouri birth certificate data for 1993 through 1999. Logistic regression was used to analyze data from 13,646 nulliparous women with preeclampsia who were delivered of singleton live births.

RESULTS

After adjustment was made for gestational age and birth weight, the data showed that women with preeclampsia at primary and secondary hospitals were more likely to be delivered by cesarean delivery (odds ratio, 1.37; 95% CI, 1.24,1.51; and odds ratio, 1.16; 95% CI, 1.07,1.26, respectively) than at tertiary hospitals. For women who were delivered at >or=37 weeks of gestation, cesarean delivery rates were 38.0%, 33.7%, and 30.0% for primary, secondary, and tertiary hospitals, respectively. Dysfunctional labor, cephalopelvic disproportion, and fetal distress were more commonly noted at primary and secondary hospitals (P<.001).

CONCLUSION

Levels of expertise and staffing at tertiary hospitals may allow greater attempts and success with vaginal delivery among women with preeclampsia compared with primary or secondary hospitals.

Age and racial/ethnic differences in maternal, fetal, and placental conditions in laboring patients

OBJECTIVE

Most health indicators exhibit evidence of ethnic disparity. This study describes the prevalence of clinical conditions that are associated with pregnancy, stratified at age 35 years, and by ethnicity (black, white, Hispanic, other).

STUDY DESIGN

This was a retrospective, cross-sectional cohort study. We used International Classification of Diseases discharge diagnostic codes from California discharge data to identify 31 maternal, fetal, and placental conditions.

RESULTS

At least one condition was present for 26.1% of the 443,532 eligible women. There was variation in risk by age and race/ethnicity and differences by age within ethnic groups. Black women were more at risk; there are 12 conditions for older women, and there are 16 conditions for younger women. Hispanic women showed a higher risk for diabetes mellitus, macrosomia, and severe hypertension. All white women showed a higher risk for cardiac conditions and isoimmunization, whereas older white women also demonstrated an increased risk for herpes infection and multiple gestation.

CONCLUSION

Older women and black women have more morbidity. The degree to which these clinical conditions affect labor management and obstetric outcomes needs further evaluation.

Using administrative data to identify indications for elective primary cesarean delivery

OBJECTIVE

To develop a methodology to identify indications and normative rates for elective primary cesarean delivery using administrative data.

DATA SOURCES/STUDY SETTING

All delivery discharges in 1995, as reported to the California Office of Statewide Health Planning and Development (secondary data).

STUDY DESIGN

Retrospective population based study.

DATA COLLECTION/EXTRACTION

Data were entered into a recursive partitioning algorithm to develop a hierarchy of conditions by which patients with multiple conditions could be sorted with respect to the binary outcome of labor or elective primary cesarean without labor. This hierarchy was examined for its clinical consistency, validated on a second sample, and compared with results obtained from logistic regression.

PRINCIPAL FINDINGS

Four percent (19,664) of delivery discharges in 1995 underwent elective primary cesarean. Twelve clinical conditions contributed to the hierarchy, and accounted for 92.9 percent of all women experiencing elective primary cesarean delivery. The remaining 7.1 percent of the elective primary cesarean cases were classified as "unspecified."

CONCLUSIONS

A standardized methodology (utilizing recursive partitioning algorithms) for assigning indications for elective primary cesarean is presented. This methodology relies on administrative data, classifies women with complex comorbidity patterns into clinically relevant subpopulations, and can be used to establish normative rates for benchmarking specific indications for cesarean delivery.