Cynthia Gyamfi-Bannerman

Antenatal Betamethasone for Women at Risk for Late Preterm Delivery

BACKGROUND Infants who are born at 34 to 36 weeks of gestation (late preterm) are at greater risk for adverse respiratory and other outcomes than those born at 37 weeks of gestation or later. It is not known whether betamethasone administered to women at risk for late preterm delivery decreases the risks of neonatal morbidities. METHODS We conducted a multicenter, randomized trial involving women with a singleton pregnancy at 34 weeks 0 days to 36 weeks 5 days of gestation who were at high risk for delivery during the late preterm period (up to 36 weeks 6 days). The participants were assigned to receive two injections of betamethasone or matching placebo 24 hours apart. The primary outcome was a neonatal composite of treatment in the first 72 hours (the use of continuous positive airway pressure or high-flow nasal cannula for at least 2 hours, supplemental oxygen with a fraction of inspired oxygen of at least 0.30 for at least 4 hours, extracorporeal membrane oxygenation, or mechanical ventilation) or stillbirth or neonatal death within 72 hours after delivery. RESULTS The primary outcome occurred in 165 of 1427 infants (11.6%) in the betamethasone group and 202 of 1400 (14.4%) in the placebo group (relative risk in the betamethasone group, 0.80; 95% confidence interval [CI], 0.66 to 0.97; P=0.02). Severe respiratory complications, transient tachypnea of the newborn, surfactant use, and bronchopulmonary dysplasia also occurred significantly less frequently in the betamethasone group. There were no significant between-group differences in the incidence of chorioamnionitis or neonatal sepsis. Neonatal hypoglycemia was more common in the betamethasone group than in the placebo group (24.0% vs. 15.0%; relative risk, 1.60; 95% CI, 1.37 to 1.87; P<0.001). CONCLUSIONS Administration of betamethasone to women at risk for late preterm delivery significantly reduced the rate of neonatal respiratory complications. (Funded by the National Heart, Lung, and Blood Institute and the Eunice Kennedy Shriver National Institute of Child Health and Human Development; ClinicalTrials.gov number, NCT01222247.).

Nonspontaneous late preterm birth: etiology and outcomes

OBJECTIVE We sought to determine the proportion of evidence-based (EB), vs non-EB (NEB) iatrogenic late preterm birth, and to compare corresponding rates of neonatal intensive care unit (NICU) admission. STUDY DESIGN We performed a retrospective cohort study. Cases were categorized as EB or NEB. NICU admission was compared between groups in both univariate and multivariate analysis. RESULTS Of 2693 late preterm deliveries, 32.3% (872/2693) were iatrogenic; 56.7% were delivered for NEB indications. Women with NEB deliveries were older (30.0 vs 28.6 years, P = .001), and more likely to be pregnant with twins (18.8% vs 7.9%, P < .001), have private insurance (80.3% vs 59.0%, P < .001), or have a second complicating factor (27.5% vs 10.1%, P < .001). A total of 56% of EB deliveries resulted in NICU admissions. After controlling for confounders, early gestational age (34 vs 36 weeks: odds ratio, 19.34; 95% confidence interval, 4.28-87.5) and mode of delivery (cesarean: odds ratio, 1.88; 95% confidence interval, 1.15-3.05) were most strongly associated with NICU admission. CONCLUSION Over half of nonspontaneous late preterm births were NEB. EB guidelines are needed.

Trends in spontaneous and indicated preterm delivery among singleton gestations in the United States, 2005-2012.

OBJECTIVE: For the first time in decades, the rate of U.S. preterm delivery has declined consistently since 2005. Recent nationwide policies enforcing elective delivery at or beyond 39 weeks of gestation suggest this decrease may be the result of changes in practice patterns; however, this is not known. Thus, we sought to evaluate whether the decline in preterm delivery was the result of a decrease in indicated or spontaneous preterm delivery and to assess this decrease by race and ethnicity. METHODS: This was a population-based retrospective analysis using U.S. vital statistics data restricted to singleton live births from 2005 to 2012. The main outcome measures were overall, indicated, and spontaneous preterm delivery rates. Preterm deliveries were defined as births from 24 to 36 weeks of gestation. We used an algorithm to designate births as indicated or spontaneous. Gestational age was further grouped into early preterm (24–31 weeks of gestation), moderate preterm (32–34 weeks of gestation), late preterm (34–36 weeks of gestation), early term (37–38 weeks of gestation), full term (39–40 weeks of gestation), late term (41 weeks of gestation), and postterm (42–44 weeks of gestation). Analyses were based on the best obstetric estimate of gestational age. RESULTS: Of 19,984,436 included births, the spontaneous preterm delivery rate declined by 15.4% between 2005 (5.3%) and 2012 (4.5%), whereas indicated preterm delivery rates declined by 17.2% (3.9 to 3.2%). The largest decline was in the postterm pregnancies (−38.5%) followed by early term (−19.1%), early preterm (−17.1%), moderate preterm (−12.4%), and late preterm (−15.8%) with concurrent increases in full term (+14.3%) and late term (+18.7%) gestations. The patterns were similar across race groups. CONCLUSION: The noted decline in preterm delivery rates is accompanied by a concurrent decline in both spontaneous and indicated preterm deliveries of almost equal magnitudes. LEVEL OF EVIDENCE: II

Epidemiology of Moderate Preterm, Late Preterm and Early Term Delivery

Moderate preterm, late preterm, and early term deliveries represent a major and growing public health concern. These deliveries are associated with significant financial burden and pose serious risks to mothers and newborns. Women who deliver at moderate and late gestational ages in one pregnancy are at increased risk of delivering at these gestational ages, or earlier, in a subsequent pregnancy. Births in moderate preterm and late preterm gestational ages are associated with significant infant morbidity and mortality. Efforts to reduce deliveries in moderate preterm and late preterm gestations and interventions designed to ameliorate the problems in infants delivered at the gestational ages may be targets worthy of future investigation.

Risk of uterine rupture and placenta accreta with prior uterine surgery outside of the lower segment

OBJECTIVE: Women with a prior myomectomy or prior classical cesarean delivery often have early delivery by cesarean because of concern for uterine rupture. Although theoretically at increased risk for placenta accreta, this risk has not been well-quantified. Our objective was to estimate and compare the risks of uterine rupture and placenta accreta in women with prior uterine surgery. METHODS: Women with prior myomectomy or prior classical cesarean delivery were compared with women with a prior low-segment transverse cesarean delivery to estimate rates of both uterine rupture and placenta accreta. RESULTS: One hundred seventy-six women with a prior myomectomy, 455 with a prior classical cesarean delivery, and 13,273 women with a prior low-segment transverse cesarean delivery were evaluated. Mean gestational age at delivery differed by group (P<.001), prior myomectomy (37.3 weeks), prior classical cesarean delivery (35.8 weeks), and low-segment transverse cesarean delivery (38.6 weeks). The frequency of uterine rupture in the prior myomectomy group (P-MMX group) was 0% (95% confidence interval [CI] 0–1.98%). The frequency of uterine rupture in the low-segment transverse cesarean delivery group (LTC group) (0.41%) was not statistically different from the risk in the P-MMX group (P>.99) or in the prior classical cesarean delivery group (PC group) (0.88%; P=.13). Placenta accreta occurred in 0% (95% CI 0–1.98%) of the P-MMX group compared with 0.19% in the LTC group (P>.99) and 0.88% in the PC group (P=.01 relative to the LTC group). The adjusted odds ratio for the PC group (relative to LTC group) was 3.23 (95% CI 1.11–9.39) for uterine rupture and 2.09 (95% CI 0.69–6.33) for accreta. The frequency of accreta for those with previa was 11.1% for the PC group and 13.6% for the LTC group (P>.99). CONCLUSION: A prior myomectomy is not associated with higher risks of either uterine rupture or placenta accreta. The absolute risks of uterine rupture and accreta after prior myomectomy are low.

Maternal microbiome – A pathway to preterm birth

Despite great medical advances in preventing maternal and infant mortality in the past century, one issue remains unresolved: why do so many women give birth prematurely? A major new field of human microbiome studies has begun to shed light on the impact of microbes (of both the commensal and pathogen varieties) on pregnancy outcomes. Recent advances in next-generation sequencing and metagenomic analysis have revealed that maternal microbiomes at a variety of niches including the oral, vaginal, gut, cervical, and even the placenta itself govern pregnancy outcomes. In this review, we describe how alterations in the microbial biomasses impact preterm birth and we discuss the major research questions concerning the cause and/or interdependent relationships between microbiome, infection, and preterm delivery.

The 5-tier system of assessing fetal heart rate tracings is superior to the 3-tier system in identifying fetal acidemia

OBJECTIVE Electronic fetal heart rate monitoring was developed to identify fetuses at risk of acidemia for intervention before adverse outcomes. Our objective was to compare the 3-tier system with a 5-tier system in evaluation of fetal acidemia. STUDY DESIGN Retrospective case-control study of patients with a fetal arterial pH <7 matched to the next birth that resulted in a pH >7.2. Tracings were categorized into 3- and 5-tier systems by a single reviewer. Sensitivities and specificities were calculated for each. RESULTS Twenty-four cases and 24 controls were identified. The sensitivity for an orange or red tracing was higher than for category III, with more of these in the pH <7 group compared with controls (P ≤ .001). There were significantly more green, blue, and yellow tracings in the normal pH group compared with the pH <7 group (P = .033, P = .008, P = .023), respectively. CONCLUSION The 5-tier system had a better sensitivity than the 3-tier system.

Diagnosis and antenatal management of congenital cytomegalovirus infection

Congenital cytomegalovirus (CMV) is the most common viral infection, affecting nearly 40,000 infants each year in the United States. Of seronegative women, 1-4% will acquire a primary infection during pregnancy, and the majority of these women will be asymptomatic. Prior maternal exposure to CMV does not preclude neonatal infection. The purpose of this document is to review diagnosis of primary maternal CMV infection, diagnosis of fetal CMV infection, and whether antenatal therapy is warranted. We recommend the following: (1) that women with a diagnosis of primary CMV infection in pregnancy be advised that the risk of congenital infection is 30-50%, on average, and that the severity of infection varies widely (Best Practice); (2) for women suspected of having primary CMV infection in pregnancy, we recommend that diagnosis should be either by IgG seroconversion or with positive CMV IgM, positive IgG, and low IgG avidity (grade 1B); (3) amniocentesis is the best option as a prenatal diagnostic tool to detect fetal congenital CMV infection, performed >21 weeks of gestation and >6 weeks from maternal infection (grade 1C); (4) we do not recommend routine screening of all pregnant women for evidence of primary CMV infection at this time (grade 1B); and (5) we do not recommend antenatal treatment with ganciclovir or valacyclovir; and we recommend that any antenatal therapy, either with antivirals or CMV hyperimmune globulin, should only be offered as part of a research protocol (Best Practice).

Prenatal and Perinatal Determinants of Lung Health and Disease in Early Life: A National Heart, Lung, and Blood Institute Workshop Report

Human lung growth and development begins with preconception exposures and continues through conception and childhood into early adulthood. Numerous environmental exposures (both positive and negative) can affect lung health and disease throughout life. Infant lung health correlates with adult lung function, but significant knowledge gaps exist regarding the influence of preconception, perinatal, and postnatal exposures on general lung health throughout life. On October 1 and 2, 2015, the National Heart, Lung, and Blood Institute convened a group of extramural investigators to develop their recommendations for the direction(s) for future research in prenatal and perinatal determinants of lung health and disease in early life and to identify opportunities for scientific advancement. They identified that future investigations will need not only to examine abnormal lung development, but also to use developing technology and resources to better define normal and/or enhanced lung health. Birth cohort studies offer key opportunities to capture the important influence of preconception and obstetric risk factors on lung health, development, and disease. These studies should include well-characterized obstetrical data and comprehensive plans for prospective follow-up. The importance of continued basic science, translational, and animal studies for providing mechanisms to explain causality using new methods cannot be overemphasized. Multidisciplinary approaches involving obstetricians, neonatologists, pediatric and adult pulmonologists, and basic scientists should be encouraged to design and conduct comprehensive and impactful research on the early stages of normal and abnormal human lung growth that influence adult outcome.

Late Preterm Birth: Management Dilemmas

In summary, late preterm birth results from spontaneous, indicated, and sometime elective indications. The burden of prematurity can be decreased if elective late preterm delivery is eliminated. While recent recommendations from the NICHD/SMFM workshop on timing of late preterm and early term birth have helped to guide management, the authors acknowledge that most of their guidelines are based on grade B or C evidence. Certain conditions absolutely warrant late preterm delivery; however, the clinician should weigh the risks of iatrogenic prematurity with the benefits of delivery for maternal or fetal indication when considering intervention for this cohort.