Accelerated fetal lung maturity profiles and maternal cocaine exposure

Evolution, Development, and Function of the Pulmonary Surfactant System in Normal and Perturbed Environments

Surfactant lipids and proteins form a surface active film at the air-liquid interface of internal gas exchange organs, including swim bladders and lungs. The system is uniquely positioned to meet both the physical challenges associated with a dynamically changing internal air-liquid interface, and the environmental challenges associated with the foreign pathogens and particles to which the internal surface is exposed. Lungs range from simple, transparent, bag-like units to complex, multilobed, compartmentalized structures. Despite this anatomical variability, the surfactant system is remarkably conserved. Here, we discuss the evolutionary origin of the surfactant system, which likely predates lungs. We describe the evolution of surfactant structure and function in invertebrates and vertebrates. We focus on changes in lipid and protein composition and surfactant function from its antiadhesive and innate immune to its alveolar stability and structural integrity functions. We discuss the biochemical, hormonal, autonomic, and mechanical factors that regulate normal surfactant secretion in mature animals. We present an analysis of the ontogeny of surfactant development among the vertebrates and the contribution of different regulatory mechanisms that control this development. We also discuss environmental (oxygen), hormonal and biochemical (glucocorticoids and glucose) and pollutant (maternal smoking, alcohol, and common "recreational" drugs) effects that impact surfactant development. On the adult surfactant system, we focus on environmental variables including temperature, pressure, and hypoxia that have shaped its evolution and we discuss the resultant biochemical, biophysical, and cellular adaptations. Finally, we discuss the effect of major modern gaseous and particulate pollutants on the lung and surfactant system.

The maternal, fetal, and neonatal effects of cocaine exposure in pregnancy

Despite multiple efforts to reduce the use of illicit drugs, the epidemic of addiction continues to be a significant public health issue. Through its easy availability, the number of people afflicted with this addiction continues to rise, including women of childbearing age. Secondarily, any health care crisis that occurs in this age group of women will have potential implications in pregnancy, infancy, and childhood. The use of cocaine alone or in conjunction with other illicit drugs, combined with the normal physiological cardiovascular changes in pregnancy, leads to a myriad of pathophysiological changes, thereby placing the life of the pregnant cocaine user, as well as the health status of their unborn fetus and neonate at risk for adverse outcomes. As more data are available, the long-term physical, mental, and developmental sequelae for children exposed to cocaine in utero prove that this public health crisis has serious implications. The pregnancy-specific maternal, fetal, and neonatal risks of cocaine use during the antepartum period are reviewed.

Identification and characterization of proteins in amniotic fluid that are differentially expressed before and after antenatal corticosteroid administration

OBJECTIVE

We sought to examine changes in the intraamniotic proteomic environment after the administration of antenatal corticosteroids to women with impending preterm delivery.

STUDY DESIGN

Amniotic fluid samples were collected at the time of clinically indicated amniocentesis before and within 7 days of administration of antenatal corticosteroids for impending preterm delivery (n = 12). Proteins differentially expressed before and after corticosteroids were identified by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry. They were isolated, characterized, and quantified by fast protein liquid chromatography, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, in-gel tryptic digestion, immunodepletion assays, enzyme-linked immunosorbent assay, and electrospray ionization tandem mass spectrometry.

RESULTS

Five protein peaks of interest were identified and characterized, all of which were significantly decreased after antenatal corticosteroid administration. These included 2 isoforms of transthyretin, albumin, prothrombin fragment 2, and lumican.

CONCLUSION

Four proteins, identified and characterized in amniotic fluid, were differentially expressed with antenatal corticosteroid administration. These data may provide additional insight into the molecular mechanisms by which antenatal corticosteroids prevent neonatal complications.

Does smoking in pregnancy modify the impact of antenatal steroids on neonatal respiratory distress syndrome? Results of the Epipage study

OBJECTIVES

To assess the relation between cigarette smoking during pregnancy and neonatal respiratory distress syndrome (RDS) in very preterm birth, and to analyse the differential effect of antenatal steroids on RDS among smokers and non-smokers.

DESIGN

A population based cohort study (the French Epipage study).

SETTING

Regionally defined births in France.

METHODS

A total of 858 very preterm liveborn singletons (27-32 completed weeks of gestation) of the French Epipage study were included in this analysis. The odds ratio for RDS in relation to smoking in pregnancy was estimated using a logistic regression to control for gestational age. The odds ratio for RDS in relation to antenatal steroids was estimated taking into account an interaction between antenatal steroids and cigarette smoking, using multiple logistic regression to control for gestational age, birthweight ratio, main causes of preterm birth, mode of delivery, and sex.

RESULTS

The odds ratio for RDS in relation to smoking in pregnancy adjusted for gestational age (aOR) was 0.59 (95% confidence interval (CI) 0.44 to 0.79). The aOR for RDS in relation to antenatal steroids was 0.31 (95% CI 0.19 to 0.49) in babies born to non-smokers and 0.63 (95% CI 0.38 to 1.05) in those born to smokers; the difference was significant (p = 0.04).

CONCLUSIONS

Cigarette smoking during pregnancy is associated with a decrease in the risk of RDS in very preterm babies. Although antenatal steroids reduce the risk of RDS in babies born to both smokers and non-smokers, the reduction is smaller in those born to smokers.

Neonatal respiratory distress syndrome as a function of gestational age and an assay for surfactant-to-albumin ratio

OBJECTIVE

Neonatal respiratory distress syndrome (RDS) affects approximately 1% of live births, and the probability of RDS continues to be a major determinant in the timing of delivery. This study was designed to investigate the optimal gestational age-specific cutoff value for a surfactant-to-albumin ratio assay for predicting RDS.

METHODS

Amniotic fluid surfactant-to-albumin ratio data were collected prospectively for a 2-year period. Women were included in the study if they delivered within 72 hours of surfactant-to-albumin ratio estimation. RDS was defined by the presence of 2 or more of the following criteria: evidence of respiratory compromise shortly after delivery and a persistent oxygen requirement for more than 24 hours, administration of exogenous pulmonary surfactant, and/or radiographic evidence of hyaline membrane disease.

RESULTS

A total of 415 mother-neonate pairs (28 RDS, 387 non-RDS) met criteria for analysis. Both gestational age and surfactant-to-albumin ratio values were independent predictors of RDS. By modeling the odds of RDS by using a logistic regression with gestational age and surfactant-to-albumin ratio values as continuous variables, a probability of RDS of 15% or less can be achieved with a surfactant-to-albumin ratio cutoff of 60 mg or more surfactant/g albumin at 28 weeks of gestation, 50 or more at 30 weeks, 40 or more at 33 weeks, 30 or more at 35 weeks, and 20 or more at 37 weeks.

CONCLUSIONS

These data describe a means of stratifying the probability of neonatal RDS using both gestational age and surfactant-to-albumin ratio value and may be a useful model for clinical decision-making.

LEVEL OF EVIDENCE

II-2

Fetal effects of cocaine: an updated meta-analysis

BACKGROUND

A very large number of women in the reproductive age group consume cocaine, leading to grave concerns regarding the long term health of millions of children after in utero exposure. The results of controlled studies have been contradictory, leading to confusion, and, possible, misinformation and misperception of teratogenic risk.

OBJECTIVE

To systematically review available data on pregnancy outcome when the mother consumed cocaine.

METHODS

A meta-analysis of all epidemiologic studies based on a priori criteria was conducted. Comparisons of adverse events in subgroups of exposed vs. unexposed children were performed. Analyses were based on several exposure groups: mainly cocaine, cocaine plus polydrug, polydrug but no cocaine, and drug free.

RESULTS

Thirty three studies met our inclusion criteria. For all end points of interest (rates of major malformations, low birth weight, prematurity, placental abruption, premature rupture of membrane [PROM], and mean birth weight, length and head circumference), cocaine-exposed infants had higher risks than children of women not exposed to any drug. However, most of these adverse effects were nullified when cocaine exposed children were compared to children exposed to polydrug but no cocaine. Only the risk of placental abruption and premature rupture of membranes were statistically associated with cocaine use itself.

CONCLUSIONS

Many of the perinatal adverse effects commonly attributed to cocaine may be caused by the multiple confounders that can occur in a cocaine using mother. Only the risk for placental abruption and PROM could be statistically related to cocaine. For other adverse effects, additional studies will be needed to ensure adequate statistical power.

Cocaine in pregnancy. Recent data on maternal and fetal risks

Cocaine continues to be abused during pregnancy, creating increased demands on the health care system. Epidemiology and basic science research have identified and confirmed risks of adverse maternal and fetal effects when cocaine is used during pregnancy. These effects of cocaine in pregnant women often are influenced by a number of confounding variables. This article reviews those cocaine effects as well as recent data, which examine in greater detail the risks of adverse outcomes of prenatal cocaine exposure during pregnancy.