Neonatal morbidity after preterm delivery in the presence of documented lung maturity

Neonatal morbidity after documented fetal lung maturity in late preterm and early term infants

OBJECTIVE

Fetal lung maturity often is used as the sole criterion that late preterm infants are ready for postnatal life. We therefore tested the hypothesis that fetal lung maturity testing does not predict the absence of morbidity in late preterm infants.

STUDY DESIGN

We performed a retrospective cohort study to examine 152 infants who were born in the late preterm (34 0/7 to 36 6/7 weeks) and early term (37 0/7 to 38 6/7 weeks) periods after mature fetal lung indices and compared them with 262 infants who were born at ≥39 weeks' gestation and who were matched by mode of delivery.

RESULTS

Despite documented fetal lung maturity, infants who were born at <39 weeks had significantly higher rates of neonatal morbidities compared with infants who were born at ≥39 weeks' gestation. After adjustment for significant covariates, we found that infants who were born at <39 weeks' gestation had an increased risk of composite adverse outcome (odds ratio, 3.66; 95% confidence interval, 1.48-9.09; P < .01).

CONCLUSION

Fetal lung maturity testing is insufficient to determine an infant's readiness for postnatal life.

Biomarker tests for fetal lung maturity

The production of surfactant is a key step in fetal lung development. Surfactant decreases alveolar surface tension, thereby preventing alveolar collapse and allowing efficient gas exchange. The lack of adequate amounts of lung surfactant results in respiratory distress syndrome. Tests that assess surfactant concentrations in amniotic fluid are good predictors of infants that will not develop respiratory distress syndrome. The most frequently used test to assess fetal lung maturity (TDx FLM II) will not be available after December 2011. Therefore, we review the currently available tests for fetal lung maturity including lecithin:sphingomyelin ratio, phosphatidyl glycerol, surfactant:albumin ratio and lamellar body counts. Herein, we discuss their clinical utility and consider a suitable replacement for the future.

Preterm birth after mature fetal lung indices: is there any neonatal morbidity?

OBJECTIVE

To determine the frequency of immediate morbidities in neonates with evidence of mature fetal lung indices who delivered before 37 weeks gestation.

METHODS

A retrospective analysis was performed on pregnancies resulting in birth at < 37 weeks after mature fetal lung was documented by phosphatidylglycerol, lecithin/sphingomyelin ratio, or TDx-FLM studies. Pregnancies with multifetal gestations, maternal diabetes, or fetal anomalies were excluded.

RESULTS

179 patients were included. Eighty-one (45.3%) neonates did not sustain any morbidity, and 98 (54.7%) neonates sustained one or more morbidities. Compared to neonate without any morbidity, neonates experiencing morbidities were delivered at significantly younger gestation (35.7 ± 1.1 vs. 34.9 ± 1.5 weeks, respectively, p < 0.001) had lower birth- weight (2632.2 ± 475.5 vs. 2395.3 ± 496 g, respectively, p < 0.001), and required longer hospital stay (3.7 ± 2.8 vs. 6.9 ± 7.5 days, p < 0.001). A multivariate regression model was performed to control for the effect of birth-weight, steroid administration, and preterm premature rupture of membrane. An earlier gestational age at delivery was associated with a higher risk of neonatal morbidity. The risk of neonatal morbidity decreased by 40% (OR = 0.60, 95% CI = 0.41-0.88; p = 0.009) for each 1 week increase in gestational age.

CONCLUSION

Even in the presence of documented fetal lung maturity, major morbidities--including respiratory distress - may still occur.

Hospitalized late preterm mild preeclamptic patients with mature lung testing: what are the risks of delivery?

OBJECTIVE

To evaluate the risk of elective delivery of hospitalized patients with isolated mild preeclampsia with mature fetal lung profile compared with a cohort of patients who had preeclampsia with indicated delivery matched for gestational age.

STUDY DESIGN

Patients with mild preeclampsia requiring hospitalization between 34 and 37 weeks estimated gestational age were offered amniocentesis for assessment of fetal lung maturity. If fetal lung maturity was documented, patients were offered delivery. These cases were then compared with indicated or spontaneously delivered controls with preeclampsia matched for gestational age.

RESULT

A total of 51 cases were identified and matched with 51 controls. Sixteen case neonates (31.4%) were admitted to neonatal intensive care unit compared with 21 controls (41.2%). Five cases (9.8%) in each group developed respiratory distress syndrome (RDS).

CONCLUSION

Elective delivery of mild preeclampsia with mature lung profiles in the late preterm gestation is not without neonatal risks, including a 10% risk of RDS in this series.

Progesterone for the prevention of preterm birth among women at increased risk: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

This study was undertaken to determine whether progestational agents, initiated in the second trimester of pregnancy, reduce the risk of delivery less than 37 weeks, among women at increased risk of spontaneous preterm birth.

STUDY DESIGN

Medline, pre-Medline, EMBASE, and Cochrane Central Register of Controlled Trials were searched. Randomized controlled trials with less than 20% lost to follow-up were included.

RESULTS

Three trials were eligible for inclusion. There was a significant reduction in risk of delivery less than 37 weeks with progestational agents (relative risk [95% CI] = 0.57 [0.36-0.90]). There was no significant effect on perinatal mortality or serious neonatal morbidity.

CONCLUSION

Progestational agents, initiated in the second trimester of pregnancy, may reduce the risk of delivery less than 37 weeks' gestation, among women at increased risk of spontaneous preterm birth, but the effect on neonatal outcome is uncertain. Larger randomized controlled trials are required to determine whether this treatment reduces perinatal mortality or serious neonatal morbidity.

Epidemiology of preterm birth and neonatal outcome

In industrialized countries, 5-11% of infants are born preterm (<37 weeks' gestation), and the rate has been increasing since the early 1980s. Preterm births account for 70% of neonatal deaths and up to 75% of neonatal morbidity, and contribute to long-term neurocognitive deficits, pulmonary dysfunction and ophthalmologic disorders. In the past several decades, major progress has been made in improving the survival of extremely premature newborns, mostly attributable to timely access to effective interventions that ameliorate prematurity-associated mortality and morbidity such as antenatal administration of corticosteroids and exogenous surfactant therapy, rather than preventing preterm births. However, the societal and healthcare costs to care for survivors with severe morbidity and neurological handicaps remain substantial. Future research should concentrate on the ways to reduce long-term health sequelae and developmental handicaps among survivors of infants born preterm, as well as elucidating the mechanisms and aetiology of preterm births.

The association between respiratory distress and nonpulmonary morbidity at 34 to 36 weeks' gestation

OBJECTIVE

The study was undertaken to determine whether respiratory distress syndrome (RDS) is associated with an increased risk of nonpulmonary morbidity in neonates born between 34 to 36 weeks' gestation.

STUDY DESIGN

We performed a matched case-control study of 75 infants with (cases) and 75 without (controls) RDS, delivered between 34 and 36 weeks' gestation. Infants with RDS and no other causes for respiratory failure (anomalies, hydrops, asphyxia) were included. Controls were matched for gestational age at birth, year of care, gender, plurality, and race. Inpatient records were reviewed for the incidence of nonpulmonary morbidities before discharge. McNemar test and conditional logistic regression were used to evaluate differences between cases and controls.

RESULTS

Our study cohort was 69% male, 48% white, 33% African American, and 19% Hispanic. Cases had longer hospital (11 vs 7days) and neonatal intensive care unit stays (10 vs 7 days), and more frequent apnea-bradycardia (30% vs 5%), pneumonia (12% vs 1%), and suspected sepsis diagnoses (27% vs 3%), P <or=.008 for each. Antibiotic use (96% vs 45%), transfusion (20% vs 0%), phototherapy (57% vs 29%), and hyperalimentation (57% vs 4%) were more common in the RDS group, P <or=.002 for each. Other major morbidities (intraventricular hemorrhage, patent ductus arteriosus, necrotizing enterocolitis, bronchopulmonary dysplasia) were uncommon in cases and controls. Similar results were obtained when controlling for mode of delivery and antenatal steroid use.

CONCLUSION

RDS at 34 to 36 weeks is associated with increased morbidity and neonatal interventions. In the absence of RDS, major morbidity is uncommon.

Maturity testing with preterm premature rupture of the membranes

The presence or absence of fetal pulmonary maturity as assessed by amniotic fluid analysis and the role of fetal maturity tests in the management of premature rupture of the membranes are addressed. The hazards of the high falsely immature test are carefully explored. A management scheme based on the results of amniotic fluid analysis is also described.

Preterm labour at 34--36 weeks of gestation: should it be arrested?

Currently, preterm labour is treated with tocolytic agents and prenatal steroids until the 34th week of gestation only. Our objective in this study was to assess this practice. Seven-year records of all preterm infants born in our institution at 34--36 weeks of gestation, were evaluated retrospectively. All babies, born in singleton well-dated pregnancies, without maternal, medical or obstetric complications, and by normal vaginal delivery, were included. Their length of hospital stay and perinatal complications were compared across gestational age groups of 34, 35 and 36 weeks. Of the 207 babies included, statistically significant reductions in the rates of respiratory distress syndrome (15.0% vs. 3.2%), nosocomial sepsis (5.0% vs. 0%) and apnoea of prematurity (11.7% vs. 2.2%), and consequently, in length of hospital stay (16 +/- 2.7 vs. 4 +/- 0.3 days) occurred between 34 and 36 weeks of gestation. The severity of respiratory distress syndrome also declined significantly. The changes were most noticeable after 35 weeks of gestation, and it was concluded that neonatal complications are still prevalent at 34 and 35 weeks. Therefore, we propose that labour should not be induced at 34 and 35 weeks of gestation and that tocolytic agents and maternal prenatal steroids may be considered in preterm labour during this period.

Delivery of the marginally preterm infant: what are the minor morbidities?

OBJECTIVE

We sought to determine frequencies of minor morbidities associated with delivery between 32 and 36 weeks' gestation.

STUDY DESIGN

The study population consisted of all infants delivered between 32 and 36 weeks' gestation at a tertiary care hospital during 1997. Maternal and neonatal charts were abstracted for maternal history, pregnancy complications, and neonatal demographics comparing complications present at each gestational week. The Student t test, chi(2) analysis, and stepwise regression analysis were used to assess statistical significance. Odds ratios were calculated.

RESULTS

There were 553 patients eligible for study. There was increased risk of neonatal intensive care unit admission with delivery before 34 weeks' gestation (P <.04). An increased incidence of feeding difficulties was present before 35 weeks' gestation (P <.001). Hypothermia remained more frequent until 35 weeks' gestation (P <.05). Delivery at 35 weeks' gestation did not increase the mean number of neonatal hospital days.

CONCLUSION

Although the incidences of major morbidities decline after 32 weeks' gestation, minor morbidities continue up to 35 to 36 weeks' gestation and may lengthen neonatal hospitalization.

In pregnancies with gestational diabetes mellitus and intensive therapy, perinatal outcome is worse in small-for-gestational-age newborns

OBJECTIVE

This study analyzed the relationship between birth weight and perinatal outcome among women with gestational diabetes mellitus.

STUDY DESIGN

The relationship between perinatal outcome and birth weight was analyzed for 821 pregnancies of women with gestational diabetes mellitus attended in a tertiary hospital and receiving intensive metabolic therapy (normocaloric diet, self-monitoring of blood glucose level and individually tailored insulin regimen when needed). The Mantel-Haenszel test was used to adjust for preterm delivery.

RESULTS

Seven percent of neonates were small for gestational age, 85% were appropriate for gestational age, and 8% were large for gestational age. After adjustment for preterm delivery the rates of adverse fetal outcome, low 1-minute Apgar score, and hypoglycemia were greater among small for gestational age neonates than among appropriate and large for gestational age infants (odds ratios 3.08, 2.51, and 3.17, respectively).

CONCLUSION

Among women with gestational diabetes mellitus who are receiving intensive therapy, perinatal outcome is worse for small for gestational age neonates than for appropriate and large for gestational age neonates.

Maternal and perinatal outcome of temporizing management in 254 consecutive patients with severe pre-eclampsia remote from term

OBJECTIVE

To assess maternal and perinatal outcomes of expectant management with plasma volume expansion and pharmacologic vasodilatation in patients with severe pre-eclampsia remote from term.

STUDY DESIGN

All women with severe pre-eclampsia between 20 and 32 weeks' gestation, not in labor and with a live, single fetus admitted to the University Hospital Rotterdam from 1985 to 1993 were managed with the intention to prolong gestation. Treatment consisted of correction of the maternal circulation with vasodilatation by means of dihydralazine and plasma volume expansion under central hemodynamic monitoring. Primary end-points of the study were prolongation of gestation, maternal antepartum and postpartum complications, and fetal and neonatal outcome.

RESULTS

Two-hundred fifty-four patients were included. The median prolongation of pregnancy was 14 (range 0-62) days. Hemodynamic treatment was associated with marked objective and subjective improvement in maternal condition. Complications of central hemodynamic monitoring were not observed. Perinatal mortality was 20.5%.

CONCLUSION

Expectant management with plasma volume expansion and pharmacologic vasodilatation under central hemodynamic monitoring of the maternal circulation may delay delivery and enhance fetal maturity and does not appear to be associated with an increased risk of maternal morbidity and mortality.