Implementing Provider‐based Sampling for the National Children's Study: Opportunities and Challenges

Background:  The National Children's Study (NCS) was established as a national probability sample of births to prospectively study children's health starting from in utero to age 21. The primary sampling unit was 105 study locations (typically a county). The secondary sampling unit was the geographic unit (segment), but this was subsequently perceived to be an inefficient strategy. Methods and Results:  This paper proposes that second‐stage sampling using prenatal care providers is an efficient and cost‐effective method for deriving a national probability sample of births in the US. It offers a rationale for provider‐based sampling and discusses a number of strategies for assembling a sampling frame of providers. Also presented are special challenges to provider‐based sampling pregnancies, including optimising key sample parameters, retaining geographic diversity, determining the types of providers to include in the sample frame, recruiting women who do not receive prenatal care, and using community engagement to enrol women. There will also be substantial operational challenges to sampling provider groups. Conclusion:  We argue that probability sampling is mandatory to capture the full variation in exposure and outcomes expected in a national cohort study, to provide valid and generalisable risk estimates, and to accurately estimate policy (such as screening) benefits from associations reported in the NCS.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94504/1/ppe12005.pd

Effect of 2 stitches vs 1 stitch on the prevention of preterm birth in women with singleton pregnancies who undergo cervical cerclage

OBJECTIVE: This study investigates whether 2 cerclage stitches are more effective than 1 stitch in the prevention of preterm birth. STUDY DESIGN: This is a retrospective cohort study of 150 singleton pregnancies that underwent cervical cerclage. Gestational age at delivery and clinical characteristics were compared. RESULTS: One hundred twelve patients (74.7%) received 1 stitch, and 38 patients (25.3%) received 2 stitches. There were no baseline differences between the groups. Analysis showed no significant difference in gestational age at delivery between the 1 vs 2 cerclage groups overall (median, 38.0 vs 38.3 weeks of gestation, respectively; P = .356) or for a given gestational age cut-off (< 37 weeks of gestation: 37.4% vs 34.2% [P = .727]; < 34 weeks of gestation: 16.8% vs 18.4% [P = .823]; < 28 weeks of gestation: 9.4% vs 2.6% [P =.179]). CONCLUSION: This study shows no measurable benefit to the placement of 2 stitches over 1 stitch during cervical cerclage in singleton pregnancies; however, further study of preterm birth at < 28 weeks of gestation and postcerclage outcomes among a larger cohort is merited

Placenta Accreta: A Spectrum of Predictable Risk, Diagnosis, and Morbidity

Abstract Objective  Placenta accreta is a feared pathology, in part, because prenatal diagnosis is imperfect. It is not known whether clinical risk factors or sonographic features equally predict the entire graded pathological spectrum of placental overinvasion disease nor whether clinical outcomes differ along the spectrum. Study Design  We conducted a mixed methods retrospective study of a cohort of women screened sonographically for placenta accreta, cross-referenced against cases identified by pathological diagnosis ( N  = 416). Demographic, diagnostic, and outcome information were compared across the spectrum of invasive placentation: percreta, increta, accreta, and focal accreta not requiring hysterectomy. The t -test, chi-square, Mann–Whitney, and Kruskal–Wallis tests were used for statistical analysis across groups. Results  As the depth of invasion decreased, risk factors for placental overinvasion were less common, especially placenta previa and previous cesarean. There was also reduced anticipation by sonographic examination of the placenta. Rates of adverse outcomes were lower among women with focal accreta compared with those with deeper invasion. Conclusion  As the depth of invasion decreases, clinical risk factors and sonographic evaluation are less reliable in the antenatal prediction of placenta accreta. The potential for unanticipated morbidity underscores the need for improved diagnostic tools for placenta accreta spectrum

Severe cardiovascular morbidity in women with hypertensive diseases during delivery hospitalization

Cardiovascular disease is the leading cause of pregnancy-related death in the United States. Identification of short-term indicators of cardiovascular morbidity has the potential to alter the course of this devastating disease among women. It has been established that hypertensive disorders of pregnancy are associated with increased risk of cardiovascular disease 10–30 years after delivery; however, little is known about the association of hypertensive disorders of pregnancy with cardiovascular morbidity during the delivery hospitalization. We aimed to identify the immediate risk of cardiovascular morbidity during the delivery hospitalization among women who experienced a hypertensive disorder of pregnancy. This retrospective cohort study of women, 15–55 years old with a singleton gestation between 2008 and 2012 in New York City, examined the risk of severe cardiovascular morbidity in women with hypertensive disorders of pregnancy compared with normotensive women during their delivery hospitalization. Women with a history of chronic hypertension, diabetes mellitus, or cardiovascular disease were excluded. Mortality and severe cardiovascular morbidity (myocardial infarction, cerebrovascular disease, acute heart failure, heart failure or arrest during labor or procedure, cardiomyopathy, cardiac arrest and ventricular fibrillation, or conversion of cardiac rhythm) during the delivery hospitalization were identified using birth certificates and discharge record coding. Using multivariable logistic regression, we assessed the association between hypertensive disorders of pregnancy and severe cardiovascular morbidity, adjusting for relevant sociodemographic and pregnancy-specific clinical risk factors. A total of 569,900 women met inclusion criteria. Of those women, 39,624 (6.9%) had a hypertensive disorder of pregnancy: 11,301 (1.9%) gestational hypertension; 16,117 (2.8%) preeclampsia without severe features; and 12,206 (2.1%) preeclampsia with severe features, of whom 319 (0.06%) had eclampsia. Among women with a hypertensive disorder of pregnancy, 431 experienced severe cardiovascular morbidity (10.9 per 1000 deliveries; 95% confidence interval, 9.9–11.9). Among normotensive women, 1780 women experienced severe cardiovascular morbidity (3.4 per 1000 deliveries; 95% confidence interval, 3.2–3.5). Compared with normotensive women, there was a progressively increased risk of cardiovascular morbidity with gestational hypertension (adjusted odds ratio, 1.18; 95% confidence interval, 0.92–1.52), preeclampsia without severe features (adjusted odds ratio, 1.96; 95% confidence interval, 1.66–2.32), preeclampsia with severe features (adjusted odds ratio, 3.46; 95% confidence interval, 2.99–4.00), and eclampsia (adjusted odds ratio, 12.46; 95% confidence interval, 7.69–20.22). Of the 39,624 women with hypertensive disorders of pregnancy, there were 15 maternal deaths, 14 of which involved 1 or more cases of severe cardiovascular morbidity. Hypertensive disorders of pregnancy, particularly preeclampsia with severe features and eclampsia, are significantly associated with cardiovascular morbidity during the delivery hospitalization. Increased vigilance, including diligent screening for cardiac pathology in patients with hypertensive disorders of pregnancy, may lead to decreased morbidity for mothers