Is lung maturation related to fetal growth in diabetic or hypertensive pregnancies?

Respiratory morbidity at follow-up of small-for-gestational-age infants born very prematurely

BACKGROUND

The aim of this study was to determine whether small-for-gestational-age (SGA) infants born very prematurely had increased respiratory morbidity in the neonatal period and at follow-up.

METHODS

Data were examined from infants recruited into the United Kingdom Oscillation Study (UKOS). Of the 797 infants who were born at <29 wk of gestational age, 174 infants were SGA. Overall, 92% were exposed to antenatal corticosteroids and 97% received surfactant; follow-up data at 22-28 mo were available for 367 infants.

RESULTS

After adjustment for gestational age and sex, SGA infants had higher rates of supplementary oxygen dependency at 36 wk postmenstrual age (odds ratio (OR): 3.23; 95% confidence interval: 2.03, 5.13), pulmonary hemorrhage (OR: 3.07; 95% CI: 1.82, 5.18), death (OR: 3.32; 95% CI: 2.13, 5.17), and postnatal corticosteroid requirement (OR: 2.09; 95% CI: 1.35, 3.23). After adjustment for infant and respiratory morbidity risk factors, a lower mean birth weight z-score was associated with a higher prevalence of respiratory admissions (OR: 1.40; 95% CI: 1.03, 1.88 for 1 SD change in z-score), cough (OR: 1.28; 95% CI: 1.00, 1.65), and use of chest medicines (OR: 1.32; 95% CI: 1.01, 1.73).

CONCLUSION

SGA infants who were born very prematurely, despite routine use of antenatal corticosteroids and postnatal surfactant, had increased respiratory morbidity at follow-up, which was not due to poor neonatal outcome.

Lung maturation in small for gestational age fetuses from pregnancies complicated by placental insufficiency or maternal hypertension

BACKGROUND

Clinical studies suggest that respiratory outcome of infants born preterm may be influenced by placental insufficiency and hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome. If so, one could expect to see differences in lung maturation indices (lecithin/sphingomyelin (L/S) ratio and lamellar body count (LBC)) in the amniotic fluid. The present study investigates lung maturation indices of preterm small for gestational age (SGA) fetuses with or without abnormal Doppler ultrasound examination and with or without maternal hypertension/HELLP syndrome.

STUDY DESIGN

Retrospective cohort study of 76 neonates born in our center between 1997 and 2003 with gestational age (GA) <34 weeks, birth weight <p10 for GA and available results from amniocentesis. All analyses were corrected for potential confounders.

RESULTS

The L/S ratio was significantly higher in the abnormal Doppler group as compared to the normal Doppler group (p=0.02). The L/S ratio was significantly lower in hypertensive pregnancies as compared to normotensive pregnancies (p=0.02). Subdivision of the maternal hypertension group showed a significantly lower L/S ratio in the HELLP syndrome group as compared to the normotension group (p=0.04).

CONCLUSION

The L/S ratio of SGA fetuses is significantly higher in cases with presumed placental insufficiency and significantly lower when pregnancies are complicated by HELLP syndrome. These observations are in line with the hypothesis that placental insufficiency accelerates lung maturation and with recent reports of poorer respiratory outcome in infants from mothers with HELLP syndrome.

Fetal adaptation to stress. Part I: acceleration of fetal maturation and earlier birth triggered by placental insufficiency in humans

This review is an attempt to provide an integrative view for the biological changes triggered by fetal stress through a multidisciplinary approach. Acceleration of brain and lung maturation in certain risk pregnancies was first described clinically and confirmed by biochemical, electrophysiological and experimental data. Moreover, new experimental findings suggest that a fetal clock centrally mediated by fetal nutritional status could determine timing of parturition. However, some skepticism persisted about the usefulness of this body of knowledge for obstetrical management in developed countries. The interest concerning this adaptation to intrauterine stress was later renewed from various sources, as developed in Part II.

The controversy surrounding fetal lung maturity in diabetes in pregnancy: a re-evaluation

It is beyond the scope of this article to discuss the biochemical markers of fetal lung maturity and their pathophysiological characteristics. This information can be found in several textbooks and review articles. Instead, this article addresses controversial issues that confront the obstetrician in daily clinical practice related to the role of diabetes (glucose) as the teratogen for lung morbidity, and the association between lung maturity testing results and actual lung morbidity.

A spectrum of glucose thresholds may effectively prevent complications in the pregnant diabetic patient

This article outlines the probable positive relationship between levels of maternal glycemia and perinatal morbidity and mortality. A spectrum of different glucose thresholds can be established and used appropriately to prevent each complication. This article also outlines the concept of normality and what definitions of normality should be used to evaluate the relationship between the level of glycemia and perinatal outcome. Definitive conclusions are hampered by a lack of uniformity in definitions and interventions, and by a failure in some analyses to control for confounding variables. However, it is suggested that different levels of glycemia are required to prevent different diabetic complications. Thus, although it is not always possible to achieve targeted levels of glycemic control in all patients, any improvement will be beneficial because it will affect fetal complications associated with that glucose threshold.

Morbidity and mortality among very-low-birth-weight neonates with intrauterine growth restriction. The Vermont Oxford Network

OBJECTIVE

We sought to determine the associations between intrauterine growth restriction and neonatal morbidity and mortality, as well as the impact of prenatal glucocorticoid administration on the frequency of specific complications of prematurity among neonates with intrauterine growth restriction.

STUDY DESIGN

We examined the association between intrauterine growth restriction and adverse neonatal outcomes in a population of 19,759 singleton very-low-birth-weight neonates without major birth defects. We included neonates from 25 to 30 weeks' gestation entered in the Vermont Oxford Network database between 1991 and 1996 by 196 institutions. Intrauterine growth restriction was defined as the 10th percentile for birth weight according to the 1993 US national statistics. Odds ratios were estimated according to stepwise logistic regression for each neonatal outcome. Potential explanatory variables included gestational age, intrauterine growth restriction, race, prenatal care, prenatal glucocorticoid administration, route of delivery, fetal sex, and birth within versus postnatal transfer to a network institution.

RESULTS

There was a statistically significant association of intrauterine growth restriction with neonatal death (odds ratio, 2.77; 95% confidence interval, 2.31-3. 33), necrotizing enterocolitis (odds ratio, 1.27; 95% confidence interval, 1.05-1.53), and respiratory distress syndrome (odds ratio, 1.19; 95% confidence interval, 1.03-1.36). There was a trend (P <. 10) toward association of intrauterine growth restriction with increased risks of intraventricular hemorrhage (odds ratio, 1.13; 95% confidence interval, 0.99-1.29) and severe intraventricular hemorrhage (grades III and IV; odds ratio, 1.25; 95% confidence interval, 0.98-1.59). Maternal prenatal glucocorticoid administration was associated with significantly lower risks of respiratory distress syndrome (odds ratio, 0.51; 95% confidence interval, 0.44-0.58), intraventricular hemorrhage (odds ratio, 0.67; 95% confidence interval, 0.61-0.73), severe intraventricular hemorrhage (odds ratio, 0.50; 95% confidence interval, 0.43-0.57), and death (odds ratio, 0.54; 95% confidence interval, 0.48-0.62). The benefits of prenatal glucocorticoid therapy for growth-restricted newborns were similar to those among normally grown infants.

CONCLUSIONS

Intrauterine growth restriction within the range of 501 to 1500 g birth weight is associated with increased risks of neonatal death, necrotizing enterocolitis, and respiratory distress syndrome. Prenatal corticosteroid use was associated with decreased risks of all outcomes studied except necrotizing enterocolitis. We found no evidence that this benefit was dependent on fetal size.

Level of glycemia and perinatal outcome in pregestational diabetes

This article provides the reader with relevant information regarding the association between level of glycemia and perinatal outcome in preexisting diabetes. Although the glycemic profile is a continuum in nature, different thresholds of glucose are associated with fetal complications such as stillbirth, spontaneous abortion, congenital anomalies, fetal macrosomia, and metabolic and respiratory complications. For each complication, a different targeted threshold of normality is required. Thus, although it is not always possible to achieve optimal glycemic control in all patients, any improvement will be beneficial because it will reduce the rate of complications for a given glucose threshold.

Management of gestational diabetes mellitus

This article addresses management of gestational diabetes in a two part fashion. It discusses the pathophysiology and pathogenesis of diabetes and outlines the contemporary management approach for gestational diabetes in the 1990s.