Obstetrician-gynecologists' knowledge and training about antenatal corticosteroids

Cardiovascular risk factors after antenatal exposure to betamethasone: 30-year follow-up of a randomised controlled trial

BACKGROUND

Antenatal betamethasone treatment is widely used for the prevention of neonatal respiratory distress syndrome in preterm infants and substantially reduces neonatal mortality and morbidity. Fetal exposure to excess glucocorticoids has been proposed as one of the core mechanisms of the fetal origins of adult disease hypothesis. We assessed whether antenatal exposure to betamethasone for the prevention of neonatal respiratory distress syndrome affects cardiovascular risk factors at 30 years of age.

METHODS

We followed up at age 30 years 534 individuals whose mothers participated in a double-blind, placebo-controlled, randomised trial of antenatal betamethasone for the prevention of neonatal respiratory distress syndrome. Mothers received two doses of betamethasone or placebo given by intramuscular injection 24 h apart. Follow-up assessments included anthropometry; measurement of blood pressure, blood lipids (after overnight fasting), and early morning cortisol levels; and a 75 g oral glucose tolerance test.

FINDINGS

There were no differences between those exposed to betamethasone and to placebo in body size, blood lipids, blood pressure, plasma cortisol, prevalence of diabetes, or history of cardiovascular disease. After a 75 g oral glucose tolerance test, participants exposed to betamethasone had higher plasma insulin concentrations at 30 min (60.5 vs 52.0 mIU/L; ratio of geometric means 1.16 [95% CI 1.03 to 1.31], p=0.02) and lower glucose concentrations at 120 min (4.8 vs 5.1 mmol/L; difference -0.26 mmol/L [-0.53 to 0.00], p=0.05) than did those exposed to placebo.

INTERPRETATION

Antenatal exposure to betamethasone might result in insulin resistance in adult offspring, but has no clinical effect on cardiovascular risk factors at 30 years of age. Thus, obstetricians should continue to use a single course of antenatal betamethasone for the prevention of neonatal respiratory distress syndrome.

Antenatal corticosteroids for fetal maturation in women at risk for preterm delivery

The available data unambiguously support the beneficial, short-term fetal effects of antenatal corticosteroids in women at risk for preterm delivery. There are still several incompletely addressed questions, including the use of corticosteroids in women with preterm premature rupture of membranes, the optimal corticosteroid preparation to be used, and the impact of repeated dosing. These issues are discussed in this review from the perspective of recent scientific evidence on the mechanisms responsible for positive short-term effects on survival and possible harmful long-term effects.

Repeat prenatal corticosteroids: Who still recommends their use and why?

BACKGROUND

Repeat prenatal corticosteroids have been in common use worldwide, even though the National Institutes of Health recommends that 'Until data establish a favourable benefit-to-risk ratio, repeat courses of antenatal corticosteroids, including rescue therapy, should be reserved for patients enrolled in clinical trials.'

OBJECTIVES

To describe the current use/recommendations for the use of repeat prenatal corticosteroids by obstetricians and neonatologists and to examine the sources of evidence on which their practice is based.

DESIGN

Postal questionnaire.

POPULATION

All Trainees, Members and Fellows of the Royal Australian and New Zealand College of Obstetricians and Gynaecologists and neonatologists in Australia and New Zealand.

METHODS

The questionnaire was mailed to obstetricians and neonatologists in August-September 2001.

MAIN OUTCOME MEASURES

Practitioner use/recommendations for the use of repeat prenatal corticosteroids and the sources of evidence on which their practice was based.

RESULTS

Use of repeat prenatal corticosteroids was recommended by 332 (44%) obstetricians and 19 (21%) neonatologists. Obstetricians were twice as likely to recommend their use compared with neonatologists (relative risk, 2.04; 95% confidence intervals, 1.36-3.06; P < 0.001). Over half of the respondents (483, 57%) reported they had changed their use/recommendations in the previous 3 years. The sources of evidence behind these practices differed between obstetricians and neonatologists and between those practitioners who recommended the use of repeat prenatal corticosteroids and those who did not.

CONCLUSIONS

Fewer practitioners recommend repeat prenatal corticosteroids compared with previous surveys. Sources of evidence behind the practice of groups of obstetricians and neonatologists differ.

Maternal dexamethasone increases endothelin-1 sensitivity and endothelin a receptor expression in ovine foetal placental arteries

Despite National Institutes of Health recommendations to administer antenatal steroids as a single course to women threatening preterm delivery, repeated treatments are often given. We investigated effects of repeated dexamethasone (DM) administered to the ewe on small maternal and foetal placental arteries. We hypothesized that DM would increase responsiveness to endothelin-1 (ET-1) and norepinephrine (NE) and that foetal arteries would react differently to ET-1 and NE compared to maternal arteries. Ewes received three treatments beginning at 103, 110, and 117 days of gestation (dGA). Each treatment consisted of four IM injections of 2mg DM or saline at 12-h intervals. At 119 dGA, in vitro functional studies were performed using Mulvany wire myography and endothelin receptor (ETR) expression was quantified using real-time RTPCR and receptor ligand autoradiography. Foetal placental arteries demonstrated greater maximal contractility to ET-1 and lesser maximal contractility to NE compared to maternal arteries. DM increased the maximal contraction elicited by ET-1 and NE in foetal but not maternal placental arteries. DM also increased the abundance of type-A ETR but not type-B ETR mRNA in foetal but not maternal placental arteries. However, within the whole placentome, DM increased the abundance of type-B ETR and decreased type-A ETR mRNA, which was confirmed by similar changes in ETR binding specifically within the labyrinth region. In summary, repeated DM treatment results in agonist and vascular bed specific responses within the placenta.

The benefit of preterm birth at tertiary care centers is related to gestational age

OBJECTIVE

The purpose of this study was to examine the relationship between gestational age and outcomes of outborn versus inborn preterm infants.

STUDY DESIGN

Multivariable logistic regression analysis was used to examine gestational age-specific, risk-adjusted outcomes of 2962 singleton infants who were born at <32 weeks of gestation who were admitted to 17 Canadian neonatal intensive care units from 1996 through 1997.

RESULTS

The risk-adjusted incidence was significantly (P <.05) higher among outborn versus inborn infants for mortality rates (odds ratio, 2.2) and > or =grade 3 intraventricular hemorrhage (odds ratio, 2.1) at < or =26 weeks of gestation and for chronic lung disease (odds ratio, 1.7) at 27 to 29 weeks of gestation. Outcomes of outborn and inborn infants at 30 to 31 weeks of gestation were not significantly different.

CONCLUSION

The short-term benefit of preterm birth at tertiary centers is related inversely to gestational age and may not extend beyond 29 weeks of gestation.

Practice trends in outpatient obstetrics and gynecology: findings of the Collaborative Ambulatory Research Network, 1995--2000

Historically, obstetrics and gynecology has been a medical/surgical specialty focusing on women's health and reproductive concerns during the childbearing years. Newer responsibilities-for example, in primary care, gerontology, and genetics-require Ob-Gyns to draw upon a base of medical knowledge that traditionally was not considered germane to their practices. Ob-Gyns are increasingly providing more primary care services to their patients; consequently, the field has expanded considerably. The Collaborative Ambulatory Research Network (CARN) was created in 1990 as a vehicle for investigating issues pertinent to women's health and to the practice of obstetrics and gynecology in the outpatient setting. This article summarizes the findings of CARN studies from 1995 to 2000, covering a range of topics related to women's health across the life cycle, including, but not limited to perinatal care. Topics include nutrition, infectious disease, hormone replacement therapy, psychosocial issues, and genetic testing in obstetric and gynecologic practice. Each study produced a picture of current practice patterns and knowledge of the physicians surveyed. Findings on knowledge, attitudes, and practices varied widely. Overall, Ob-Gyns were knowledgeable and consistent in more traditional areas of practice. Conversely, inconsistencies were observed in newer areas.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians

LEARNING OBJECTIVES

After completion of this article, the reader will be able to define what the Collaborative Ambulatory Research Network (CARN) involves, describe how CARN obtains its data, and summarize some of the findings of CARN from the years 1995 to 2000.