Faculty Bibliography

OBJECTIVE:To examine age-period-cohort effects on trends in gestational diabetes mellitus (GDM) prevalence in the US, and to evaluate how these trends have affected the rates of stillbirth and large for gestational age (LGA)/macrosomia. DESIGN:Retrospective cohort study. SETTING:USA, 1979-2010. POPULATION:Over 125 million pregnancies (3 337 284 GDM cases) associated with hospitalisations. METHODS:Trends in GDM prevalence were examined via weighted Poisson models to parse out the extent to which GDM trends can be attributed to maternal age, period of delivery, and maternal birth cohort. Multilevel models were used to assess the contribution of population effects to the rate of GDM. Log-linear Poisson regression models were used to estimate the contributions of the increasing GDM rates to changes in the rates of LGA and stillbirth between 1979-81 and 2008-10. MAIN OUTCOME MEASURES:Rates and rate ratios (RRs). RESULTS:Compared with 1979-1980 (0.3%), the rate of GDM has increased to 5.8% in 2008-10, indicating a strong period effect. Substantial age and modest cohort effects were evident. The period effect is partly explained by period trends in body mass index (BMI), race, and maternal smoking. The increasing prevalence of GDM is associated with a 184% (95% CI 180-188%) decline in the rate of LGA/macrosomia and a 0.75% (95% CI 0.74-0.76) increase in the rate of stillbirths for 2008-10, compared with 1979-81. CONCLUSIONS:The temporal increase in GDM can be attributed to period of pregnancy and age. Increasing BMI appears to partially contribute to the GDM increase in the US. TWEETABLE ABSTRACT:The increasing prevalence of GDM can be attributed to period of delivery and increasing maternal age.

PURPOSE/OBJECTIVE:To determine the association between obstetric outcomes and publicly reported hospital data on patient satisfaction, surgical quality measures and medical outcomes. MATERIALS AND METHODS/METHODS:Hospitals in the Nationwide Inpatient Sample in 2011 were linked to Hospital Compare, a source of hospital data on patient satisfaction, quality and mortality for medical conditions. The risk-adjusted hospital-level rates of obstetric morbidity, episiotomy and lacerations were compared across the hospitals and reported as the absolute reduction in risk (ARR). RESULTS:We identified 528 708 women. There was no association between any of the metrics and risk-adjusted obstetric morbidity (range -0.15% to 0.03% difference). Hospitals with a high mortality rate for pneumonia had a 0.38% (95% CI: 0.13% to 0.64%) higher rate of risk-adjusted third- and fourth-degree lacerations, while hospitals with a higher death rate for myocardial infarction had a -0.74% (95% CI, -1.34% to -0.14%) lower risk-adjusted episiotomy rate. The differences in the remainder of the publicly reported metrics and the risk adjusted rates of third- and fourth-degree lacerations and episiotomy were small and not statistically significant (p  > 0.05). CONCLUSION/CONCLUSIONS:There is little association between currently available, publically reported hospital data and obstetric quality. Obstetric-specific hospital measures of quality and satisfaction are needed.

OBJECTIVE:We examined rates of serious maternal complications in relation to severe pre-eclampsia based on the delivering hospital's annualised volume. DESIGN/METHODS:Retrospective cohort study. POPULATION AND SETTING/METHODS:Singleton deliveries (n = 25 782 235) in 439 hospitals in the USA. METHODS:Annualised hospital volume was categorised as 25-500, 501-1000, 1001-2000 and >2000. MAIN OUTCOME MEASURES/METHODS:Rates of in-hospital maternal death and serious maternal complications, including puerperal cerebrovascular disorders, pulmonary oedema, disseminated intravascular coagulation, acute renal, heart and liver failure, sepsis, haemorrhage and intubation in relation to severe pre-eclampsia. We derived adjusted risk ratio (RR) and 95% confidence interval (CI), from hierarchical Poisson regression models. RESULTS:Severe pre-eclampsia was associated with an 8.7-fold (95% CI 7.6, 10.1) risk of composite maternal complications, with similar RRs across levels of hospital volumes. However, compared with hospitals with low annual volume (<2000), maternal mortality rates in relation to severe pre-eclampsia were lower in high volume hospitals. The rates of serious maternal complications were 410.7 per 10 000 to women who delivered in hospitals with a high rate of severe pre-eclampsia (≥2.12%) and 584.8 per 10 000 to women who delivered in hospitals with low severe pre-eclampsia rates (≤0.41; RR 1.75, 95% CI 1.24, 2.45). CONCLUSIONS:While the risks of serious maternal complications in relation to severe pre-eclampsia was similar across hospital delivery volume categories, deaths showed lower rates in large delivery volume hospitals than in smaller volume hospitals. The risk of complications was increased in hospitals with low compared with high severe pre-eclampsia rates. TWEETABLE ABSTRACT/CONCLUSIONS:Hospital volume had little impact on the association between severe pre-eclampsia and maternal complications.

BACKGROUND:While research has demonstrated increasing risk for severe maternal morbidity in the United States, risk at lower volume hospitals remains poorly characterized. More than half of all obstetric units in the United States perform <1000 deliveries per year and improving care at these hospitals may be critical to reducing risk nationwide. OBJECTIVE:We sought to characterize maternal risk profiles and severe maternal morbidity at low-volume hospitals in the United States. STUDY DESIGN/METHODS:We used data from the Nationwide Inpatient Sample to evaluate trends in severe maternal morbidity and comorbid risk during delivery hospitalizations in the United States from 1998 through 2011. Comorbid maternal risk was estimated using a comorbidity index validated for obstetric patients. Severe maternal morbidity was defined as the presence of any 1 of 15 diagnoses representative of acute organ injury and critical illness. RESULTS:A total of 2,300,279 deliveries occurred at hospitals with annual delivery volume <1000, representing 20% of delivery hospitalizations overall. There were 7849 cases (0.34%) of severe morbidity in low-volume hospitals and this risk increased over the course of the study from 0.25% in 1998 through 1999 to 0.49% in 2010 through 2011 (P < .01). The risk in hospitals with ≥1000 deliveries increased from 0.35-0.62% during the same time periods. The proportion of patients with the lowest comorbidity decreased, while the proportion of patients with highest comorbidity increased the most. The risk of severe morbidity increased across all women including those with low comorbidity scores. Risk for severe morbidity associated with obstetric hemorrhage, infection, hypertensive diseases of pregnancy, and medical conditions all increased during the study period. CONCLUSION/CONCLUSIONS:Our findings demonstrate increasing maternal risk at hospitals performing <1000 deliveries per year broadly distributed over the patient population. Rates of morbidity in centers with ≥1000 deliveries have also increased. These findings suggest that maternal safety improvements are necessary at all centers regardless of volume.

OBJECTIVE:To examine the association between first-trimester angiotensin-converting enzyme (ACE) inhibitor exposure and the risk of overall major congenital, cardiac, and central nervous system malformations. METHODS:We used a cohort of completed pregnancies linked to liveborn neonates derived from Medicaid claims from 2000 to 2010. We examined the risk of malformations associated with first-trimester exposure to an ACE inhibitor. Propensity score-based methods were used to control for potential confounders including maternal demographics, medical conditions, exposure to other medications, and measures of health care utilization. RESULTS:The cohort included 1,333,624 pregnancies, of which 4,107 (0.31%) were exposed to ACE inhibitors during the first trimester. The prevalence of overall malformations in the ACE inhibitor-exposed pregnancies was 5.9% compared with 3.3% in the unexposed (unadjusted relative risk, 1.82; 95% confidence interval [CI] 1.61-2.06), of cardiac malformations was 3.4% compared with 1.2% (relative risk 2.95, 95% CI 2.50-3.47), and of central nervous system malformations was 0.27% compared with 0.18% (relative risk 1.46, 95% CI 0.81-2.64). After restricting the cohort to pregnancies complicated by chronic hypertension (both exposed and unexposed) and accounting for other confounding factors, there was no significant increase in the risk of any of the outcomes assessed. Relative risks associated with first-trimester ACE inhibitor exposure were 0.89 (95% CI 0.75-1.06) for overall malformations, 0.95 (95% CI 0.75-1.21) for cardiac malformations, and 0.54 (95% CI 0.26-1.11) for CNS malformations. CONCLUSIONS:After accounting for confounders, among women with hypertension, exposure to ACE inhibitors during the first trimester was not associated with an increased risk of major congenital malformations.

OBJECTIVE:The objectives of this study were to determine temporal trends in forceps and vacuum delivery and factors associated with operative vaginal delivery. DESIGN/METHODS:Retrospective cohort. SETTING/METHODS:Population-based study of US birth records. POPULATION/METHODS:US births from 2005 to 2013. METHODS:This study evaluated forceps and vacuum extraction during vaginal delivery in live-born, non-anomalous singleton gestations from ≥ 36 to < 42 weeks of gestation. The primary outcomes were vacuum, forceps and overall operative delivery. Obstetric, medical and demographic characteristics associated with operative vaginal delivery were analysed. Multivariable logistic regression models were developed to determine factors associated with forceps/vacuum use. RESULTS:A total of 22 598 971 vaginal deliveries between 2005 and 2013 were included in the analysis. In all, 1 083 318 (4.8%) were vacuum-assisted and 237 792 (1.1%) were by forceps. Both vacuum and forceps deliveries decreased over the study period; vacuum deliveries decreased from 5.8% in 2005 to 4.1% in 2013, and forceps deliveries decreased from 1.4% to 0.9% during the same period. The adjusted odds ratio for forceps delivery was 0.70 (95% CI 0.69-0.72) in 2013 with 2005 as a reference. For vacuum delivery the odds ratio was 0.68 (95% CI 0.67-0.69) comparing the same years. CONCLUSION/CONCLUSIONS:Forceps and vacuum deliveries decreased during the study period. Low rates of operative delivery pose a challenge for resident education and may limit the degree to which women have access to alternatives to caesarean delivery. Initiatives that allow future generations of obstetricians to develop expertise in performing operative deliveries in the setting of decreased volume are an urgent resident education priority. TWEETABLE ABSTRACT/CONCLUSIONS:Forceps and vacuum delivery decreased significantly in the USA from 2005 to 2013.

BACKGROUND:There are limited data on how maternal age is related to twin pregnancy outcomes. OBJECTIVE:The purpose of this study was to assess the relationship between maternal age and risk for preterm birth, fetal death, and neonatal death in the setting of twin pregnancy. STUDY DESIGN:This population-based study of US birth, fetal death, and period-linked birth-infant death files from 2007-2013 evaluated neonatal outcomes for twin pregnancies. Maternal age was categorized as 15-17, 18-24, 25-29, 30-34, 35-39, and ≥40 years of age. Twin live births and fetal death delivered at 20-42 weeks were included. Primary outcomes included preterm birth (<34 weeks and <37 weeks), fetal death, and neonatal death at <28 days of life. Analyses of preterm birth at <34 and <37 weeks were adjusted for demographic and medical factors, with maternal age modeled with the use of restricted spline transformations. RESULTS:A total of 955,882 twin live births from 2007-2013 were included in the analysis. Preterm birth rates at <34 and <37 weeks gestation were highest for women 15-17 years of age, decreased across subsequent maternal age categories, nadired for women 35-39 years old, and then increased slightly for women ≥40 years old. Risk for fetal death generally decreased across maternal age categories. Risk for fetal death was 39.9 per 1000 live births for women 15-17 years old, 24.2 for women 18-24 years old, 17.8 for women 25-29 years old, 16.4 for women 30-34 years old, 17.2 for women 35-39 years old, and 15.8 for women ≥40 years old. Risk for neonatal death at <28 days was highest for neonates born to women 15-17 years old (10.0 per 1,000 live births), decreased to 7.3 for women 18-24 years old and 5.5 for women 25-29 years old and ranged from 4.3-4.6 for all subsequent maternal age categories. In adjusted models, risk for preterm birth at <34-<37 weeks gestation was not elevated for women in their mid-to-late 30s; however, risk was elevated for women <20 years old and increased progressively with age for women in their 40s. CONCLUSION:Although twin pregnancy is associated with increased risk for most adverse perinatal outcomes, this analysis did not find advanced maternal age to be an additional risk factor for fetal death and infant death. Preterm birth risk was relatively low for women in their late 30s. Risks for adverse outcomes were higher among younger women; further research is indicated to improve outcomes for this demographic group. It may be reasonable to counsel women in their 30s that their age is not a major additional risk factor for adverse obstetric outcomes in the setting of twin pregnancy.

BACKGROUND:Despite the temporal increase in cesarean deliveries, the extent to which maternal age, period, and maternal birth cohorts may have contributed to these trends remains unknown. METHODS:We performed an analysis of 123 million singleton deliveries in the United States (1979-2010). We estimated rate ratio (RR) with 95% confidence interval (CI) for primary and repeat cesarean deliveries. We examined changes in cesarean rates with weighted Poisson regression models across three time-scales: maternal age, year of delivery, and birth cohort (mother's birth year). RESULTS:The primary cesarean rate increased by 68% (95% confidence interval [CI]: 67%, 69%) between 1979 (11.0%) and 2010 (18.5%). Repeat cesarean deliveries increased by 178% (95% CI: 176, 179) from 5.2% in 1979 to 14.4% in 2010. Cesarean rates increased with advancing age. Compared with 1979, the RR for the period effect in primary and repeat cesarean deliveries increased up to 1990, fell to a nadir at 1993, and began to rise thereafter. A small birth cohort effect was evident, with women born before 1950 at increased risk of primary cesarean; no cohort effect was seen for repeat cesarean deliveries. Adjustment for maternal BMI had a small effect on these findings. Period effects in primary cesarean were explained by a combination of trends in obesity and chronic hypertension, as well as demographic shifts over time. CONCLUSIONS:Maternal age and period appear to have important contributions to the temporal increase in the cesarean rates, although the effect of parity on these associations remains undetermined.

OBJECTIVE:To characterize the use of venous thromboembolism prophylaxis during antepartum and postpartum hospitalizations in the United States. METHODS:A retrospective cohort study using the Perspective database was performed to analyze temporal trends of mechanical and pharmacologic venous thromboembolism prophylaxis for patients hospitalized for antepartum and postpartum indications between 2006 and 2015. Delivery hospitalizations were excluded. The association between use of prophylaxis and medical and obstetric risk factors as well as patient demographic and hospital characteristics was evaluated with unadjusted and adjusted models accounting for demographic, hospital and medical, and obstetric risk factors. RESULTS:A total of 622,740 antepartum and 105,361 postpartum readmissions were identified and included in the analysis. Between 2006 and 2015, use of venous thromboembolism prophylaxis increased from 18.5% to 38.7% for antepartum admissions (adjusted risk ratio [RR] 1.94, 95% CI 1.88-2.01) and from 22.5% to 30.6% for postpartum readmissions (adjusted RR 1.31, 95% CI 1.21-1.43). Among women readmitted postpartum, 56.4% of prophylaxis was pharmacologic and 43.6% was mechanical. For antepartum admissions, 87.2% of prophylaxis was mechanical and 12.8% was pharmacologic. Significant regional and hospital-level variation was noted with prophylaxis most common in the South. In both unadjusted and unadjusted analyses, use of venous thromboembolism prophylaxis was more common for women with thrombophilia, ovarian hyperstimulation syndrome, a history of venous thromboembolism, and prolonged hospitalization. Factors associated with decreased rates of prophylaxis included hyperemesis and postpartum endometritis. CONCLUSION:Although antepartum and postpartum venous thromboembolism prophylaxis is becoming increasingly common, particularly in the setting of medical or obstetric risk factors, use of prophylaxis varies regionally and on a hospital level. Some risk factors for venous thromboembolism were associated with lower rates of prophylaxis. The heterogeneity of clinical approaches to venous thromboembolism prophylaxis for these patient populations may represent an opportunity to perform outcomes research to further clarify best practices.