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

Potential Psychological and Biological Mechanisms Underlying the Effectiveness of Neonatal Music Therapy during Kangaroo Mother Care for Preterm Infants and Their Parents

Neonatal music therapy (MT) has become more accessible worldwide. Previous research suggests multiple benefits of MT for preterm infants and their caregivers; however, far too little attention has been paid to understanding the mechanisms of change in previous Neonatal Intensive Care Unit (NICU)-MT research so far. This perspective article describes potential mechanisms of MT interventions exposed during kangaroo mother care on the preterm infant's response (behavioral and physiological outcomes) and the mother-infant relationship. The paper focuses on the hypothalamic-pituitary-adrenal axis' role in stabilization of behavioral state, the autonomic nervous system's role in stabilization of physiologic state, as well as co-regulation as a potential mechanism for the developing of the parent-infant relationship. Mechanisms play a pivotal role in understanding variables related to the therapy course and well as in generating new knowledge regarding treatment susceptibility and optimizing resources. Understanding of the mechanisms of how interventions may lead to specific outcomes plays an important role in addressing the issue of improvement of currently available approaches of MT used in the NICU.

Neonatal Morbidity in Late Preterm Infants Associated with Intrauterine Growth Restriction

AIM

This study aims to compare the neonatal morbidity of Intrauterine growth restricted (IUGR) Late Preterm (LP) babies, to those born Late Preterm but evaluated as Appropriate for Gestational Age (AGA).

METHODS

The study is a 2-year prospective one that used data from the Neonatal Intensive Care Unit (NICU) charts of LP neonates born in our tertiary maternity hospital "Koço Gliozheni" in Tirana. Congenital anomalies and genetical syndromes are excluded. Neonatal morbidity of IUGR Late Preterm is compared to those born Late Preterm but evaluated as AGA. OR and CI, 95% is calculated.

RESULTS

Out of 336 LP babies treated in NICU, 88 resulted with IUGR and 206 AGA used as a control group. We found significantly higher morbidity in the IUGR group for hypoglycemia, polycythemia, feeding intolerance, birth asphyxia and seizures, secondary sepsis have higher morbidity but the difference is not significant. No differences were found for hyperbilirubinemia in both groups. No neonatal deaths were observed in both groups.

CONCLUSION

Our study showed that late preterm IUGR has a significantly higher risk for neonatal morbidity when compared to late preterm AGA babies.

Impact of Changes in Maternal Age and Parity Distribution on the Increasing Trends in the Low Birth Weight and Very Low Birth Weight Rates in South Korea, 2005-2015

OBJECTIVES

The aim of this study was to evaluate the impact of shifts in maternal age and parity on the increasing trends in the low birth weight (LBW) and very low birth weight (VLBW) rates from 2005 to 2015 in South Korea.

METHODS

Data from 4 993 041 live births registered with Statistics Korea during the period between 2005 and 2015 were analyzed. Applying a modified standardization method, we partitioned the total increment in the LBW and VLBW rates into (1) the increase in the LBW and VLBW rates due to changes in the maternal age and parity distribution (AP-dis) and (2) the increase due to changes in the age-specific and parity-specific rates (AP-spe) of LBW and VLBW for singleton and multiple births, respectively.

RESULTS

During the study period, the total increment in the LBW and VLBW rates was 1.43%p and 0.25%p, respectively. Among singleton births, changes in the AP-dis accounted for 79% (0.34%p) and 50% (0.06%p) of the total increment in the LBW and VLBW rates, respectively. Meanwhile, among multiple births, changes in the AP-dis did not contribute to the increase in the LBW and VLBW rates, with 100% of the increase in the LBW (1.00%p) and VLBW (0.13%p) rates being attributed to changes in the AP-spe.

CONCLUSIONS

This study demonstrated that shifts in maternal age and parity were prominent contributors to the increase in the LBW and VLBW rates among singleton births between 2005 and 2015 in South Korea.

Early neonatal morbidities and associated modifiable and non-modifiable risk factors in a cohort of infants born at 34-35 weeks of gestation

OBJECTIVE

To ascertain the most common early morbidities in a cohort of infants born at 34-35 weeks gestation and to identify the risk factors associated with these morbidities.

METHODS

Retrospective analysis of data collected prospectively for all 235 infants born at 34-35 weeks of gestation during an eight-month period at a single tertiary medical center. Study group infants (SG) were compared with 470 term infants (TI), matched both for gender and for mode of delivery.

RESULTS

Jaundice requiring phototherapy (32%), respiratory disease (19.1%) and cyanotic episodes (15.7%) were the most frequent early morbidities, followed by hypoglycemia, temperature instability and feeding intolerance. The risk of having a complication was 13.3-times higher in the SG compared with the TI group (95% CI 8.9-19.6, p < 0.001). Modifiable interventions associated with these morbidities were antenatal steroids, MgSO4 and mode of delivery. Non-modifiable factors were maternal age, parity, twins and gender.

CONCLUSIONS

Jaundice requiring phototherapy, respiratory disease and cyanotic episodes are the most frequent early morbidities among infants born at 34-35 weeks. Medically modifiable factors were found to be associated with the above morbidities. Whether specific recommendations for the care of these infants will affect early morbidities needs to be studied in controlled prospective studies.

[Respiratory disorders among late-preterm infants in a neonatal intensive care unit]

INTRODUCTION

The rate of infants born at 34-36 weeks of gestation has increased over the last 20 years. These babies are at higher risk of morbidity, particularly respiratory, than full-term infants are. The purpose of this study was to describe the respiratory morbidity of late-preterm infants and identify risk factors.

PATIENTS AND METHODS

This was a descriptive, single-center study including 273 late-preterm infants born in a tertiary care hospital between July 2009 and December 2010.

RESULTS

Of the mothers who delivered, 53.9% had morbidity. The cesarean-section delivery rate before labor was 20.9%; the main indication was fetal growth restriction (34%). Sixty-four percent of newborns had morbidity during their hospitalization and 23.1% suffered from respiratory distress. Mechanical ventilation was needed in 4.4% of the infants. Respiratory distress was mainly caused by early-onset sepsis or transient tachypnea. Ten infants presented with respiratory distress syndrome, of whom seven received a surfactant. Neonatal respiratory distress risk factors were gestational age, sex, and prelabor cesarean section (P<0.05).

CONCLUSION

Late-preterm infants have an increased risk of respiratory disorders requiring ventilation. Elective cesarean should be limited if possible during this period.

Acute histologic chorioamnionitis is a risk factor for adverse neonatal outcome in late preterm birth after preterm premature rupture of membranes

BACKGROUND

The objective of this study was to determine whether acute histologic chorioamnionitis is associated with adverse neonatal outcomes in late preterm infants who were born after preterm PROM.

METHODOLOGY/PRINCIPAL FINDINGS

The relationship between the presence of acute histologic chorioamnionitis and adverse neonatal outcome was examined in patients with preterm PROM who delivered singleton preterm newborns between 34 weeks and 36 6/7 weeks of gestation. Nonparametric statistics were used for data analysis. The frequency of acute histologic chorioamnionitis was 24% in patients with preterm PROM who delivered preterm newborns between 34 weeks and 36 6/7 weeks of gestation. Newborns born to mothers with histologic chorioamnionitis had significantly higher rates of adverse neonatal outcome (74% vs 51%; p<0.005) than those without histologic chorioamnionitis. This relationship remained significant after adjustment for gestational age at preterm PROM, gestational age at delivery, and exposure to antenatal corticosteroids.

CONCLUSIONS/SIGNIFICANCE

The presence of acute histologic chorioamnionitis is associated with adverse neonatal outcome in late preterm infants born to mothers with preterm PROM.

The genomics of preterm birth: from animal models to human studies

Preterm birth (delivery at less than 37 weeks of gestation) is the leading cause of infant mortality worldwide. So far, the application of animal models to understand human birth timing has not substantially revealed mechanisms that could be used to prevent prematurity. However, with amassing data implicating an important role for genetics in the timing of the onset of human labor, the use of modern genomic approaches, such as genome-wide association studies, rare variant analyses using whole-exome or genome sequencing, and family-based designs, holds enormous potential. Although some progress has been made in the search for causative genes and variants associated with preterm birth, the major genetic determinants remain to be identified. Here, we review insights from and limitations of animal models for understanding the physiology of parturition, recent human genetic and genomic studies to identify genes involved in preterm birth, and emerging areas that are likely to be informative in future investigations. Further advances in understanding fundamental mechanisms, and the development of preventative measures, will depend upon the acquisition of greater numbers of carefully phenotyped pregnancies, large-scale informatics approaches combining genomic information with information on environmental exposures, and new conceptual models for studying the interaction between the maternal and fetal genomes to personalize therapies for mothers and infants. Information emerging from these advances will help us to identify new biomarkers for earlier detection of preterm labor, develop more effective therapeutic agents, and/or promote prophylactic measures even before conception.

'The influence of gestational age and socioeconomic status on neonatal outcomes in late preterm and early term gestation: a population based study'

Background

Infants born late preterm (34 + 0 to 36 + 6 weeks GA (gestational age)) are known to have higher neonatal morbidity than term (37 + 0 to 41 + 6 weeks GA) infants. There is emerging evidence that these risks may not be homogenous within the term cohort and may be higher in early term (37 + 0 to 38 + 6 weeks GA). These risks may also be affected by socioeconomic status, a risk factor for preterm birth.

Methods

A retrospective population based cohort of infants born at 34 to 41 weeks of GA was assembled; individual and area-level income was used to develop three socioeconomic (SES) groups. Neonatal morbidity was grouped into respiratory distress syndrome (RDS), other respiratory disorders, other complications of prematurity, admission to a Level II/III nursery and receipt of phototherapy. Regression models were constructed to examine the relationship of GA and SES to neonatal morbidity while controlling for other perinatal variables.

Results

The cohort contained 25 312 infants of whom 6.1% (n = 1524) were born preterm and 32.4% (n = 8203) were of low SES. Using 39/40 weeks GA as the reference group there was a decrease in neonatal morbidity at each week of gestation. The odds ratios remained significantly higher at 37 weeks for RDS or other respiratory disorders, and at 38 weeks for all other outcomes. SES had an independent effect, increasing morbidity with odds ratios ranging from 1.2–1.5 for all outcomes except for the RDS group, where it was not significant.

Conclusions

The risks of morbidity fell throughout late preterm and early term gestation for both respiratory and non-respiratory morbidity. Low SES was associated with an independent increased risk. Recognition that the morbidities associated with prematurity continue into early term gestation and are further compounded by SES is important to develop strategies for improving care of early term infants, avoiding iatrogenic complications and prioritizing public health interventions.

Neonatal morbidity in singleton late preterm infants compared with full-term infants

AIM

The aim of this study was to test the hypothesis that singleton late preterm infants (34 0/7 to 36 6/7 weeks of gestation) compared with full-term infants have a higher incidence of short-term morbidity and stay longer in hospital.

METHODS

In this retrospective, multicentre study, electronic data of children born at five hospitals in Switzerland were recorded. Short-term outcome of late preterm infants was compared with a control group of full-term infants (39 0/7 to 40 6/7 weeks of gestation). Multiple gestations, pregnancies complicated by foetal malformations, maternal consumption of illicit drugs and infants with incomplete documentation were excluded. The results were corrected for gender imbalance.

RESULTS

Data from 530 late preterm and 1686 full-term infants were analysed. Compared with full-term infants, late preterm infants had a significant higher morbidity: respiratory distress (34.7% vs. 4.6%), hyperbilirubinaemia (47.7% vs. 3.4%), hypoglycaemia (14.3% vs. 0.6%), hypothermia (2.5% vs. 0.6%) and duration of hospitalization (mean, 9.9 days vs. 5.2 days). The risk to develop at least one complication was 7.6 (95% CI: 6.2-9.6) times higher among late preterm infants (70.8%) than among full-term infants (9.3%).

CONCLUSION

Singleton late preterm infants show considerably higher rate of medical complications and prolonged hospital stay compared with matched full-term infants and therefore need more medical and financial resources.

Trends in preterm birth: singleton and multiple pregnancies in the Netherlands, 2000-2007

OBJECTIVE

Several studies have reported increasing trends in preterm birth in developed countries, mainly attributable to an increase in medically indicated preterm births. Our aim was to describe trends in preterm birth among singleton and multiple pregnancies in the Netherlands.

DESIGN

Prospective cohort study.

SETTING

Nationwide study.

POPULATION

We studied 1,451,246 pregnant women from 2000 to 2007.

METHODS

We assessed trends in preterm birth. We subdivided preterm birth into spontaneous preterm birth after premature prelabour rupture of membranes (pPROM), medically indicated preterm birth and spontaneous preterm birth without pPROM. We performed analyses separately for singletons and multiples.

MAIN OUTCOME MEASURES

The primary outcome was preterm birth, defined as birth before 37 weeks of gestation, with very preterm birth (<32 weeks of gestation) being a secondary outcome.

RESULTS

The risk of preterm birth was 7.7% and the risk of very preterm birth was 1.3%. In singleton pregnancies, the preterm birth risk decreased significantly from 6.4% to 6.0% (P < 0.0001), mainly as a result of the decrease in spontaneous preterm birth without pPROM (3.6-3.1%, P < 0.0001). In multiple pregnancies, the preterm birth risk increased significantly (47.3-47.7%, P = 0.047), mainly as a result of medically indicated preterm birth, which increased from 15.0% to 17.9% (P < 0.0001).

CONCLUSION

In the Netherlands, the preterm birth risk in singleton pregnancies decreased significantly over the years. The trend of increasing preterm birth risk reported in other countries was only observed in (medically indicated) preterm birth in multiple pregnancies.

Late preterm infants: birth outcomes and health care utilization in the first year

OBJECTIVE

To distinguish the effects of late preterm birth from the complications associated with the causes of delivery timing, this study used propensity score-matching methods on a statewide database that contains information on both mothers and infants.

METHODS

Data for this study came from Arkansas Medicaid claims data linked to state birth certificate data for the years 2001 through 2005. We excluded all multiple births, infants with birth defects, and infants at <33 weeks of gestation. Late preterm infants (LPIs) (34 to 36 weeks of gestation) were matched with term infants (37-42 weeks of gestation) according to propensity scores, on the basis of infant, maternal, and clinical characteristics.

RESULTS

A total of 5188 LPIs were matched successfully with 15303 term infants. LPIs had increased odds of poor outcomes during their birth hospitalization, including a need for mechanical ventilation (adjusted odds ratio [aOR]: 1.31 [95% confidence interval [CI]: 1.01-1.68]), respiratory distress syndrome (aOR: 2.84 [95% CI: 2.33-3.45]), and hypoglycemia (aOR: 1.60 [95% CI: 1.26-2.03]). Outpatient and inpatient Medicaid expenditures in the first year were both modestly higher (outpatient, adjusted marginal effect: $108 [95% CI: $58-$158]; inpatient, $597 [95% CI: $528-$666]) for LPIs.

CONCLUSIONS

LPIs are at increased risk of poor health-related outcomes during their birth hospitalization and of increased health care utilization during their first year.

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.

Neonatal outcomes of late-preterm birth associated or not with intrauterine growth restriction

Objective. To compare neonatal morbidity and mortality between late-preterm intrauterine growth-restricted (IUGR) and appropriate-for-gestational-age (AGA) infants of the comparable gestational ages (GAs). Methods. We retrospectively analyzed neonatal morbidity and mortality of 50 singleton pregnancies involving fetuses with IUGR delivered between 34 and 36 6/7 weeks of GA due to maternal and/or fetal indication. The control group consisted of 36 singleton pregnancies with spontaneous preterm delivery at the same GA, in which the infant was AGA. Categorical data were compared between IUGR and AGA pregnancies by X² analysis and Fisher's exact test. Ordinal measures were compared using the Kruskal-Wallis test. Results. The length of stay of newborns in the nursery, as well as the need for and duration of hospitalization in the neonatal intensive care unit, was longer in the group with IUGR. Transient tachypnea of the newborn or apnea rates did not differ significantly between the IUGR and AGA groups. IUGR infants were found to be at a higher risk of intraventricular hemorrhage. No respiratory distress syndrome, pulmonary hemorrhage or bronchopulmonary dysplasia was observed in either group. The frequency of sepsis, thrombocytopenia and hyperbilirubinemia was similar in the two groups. Hypoglycemia was more frequent in the IUGR group. No neonatal death was observed. Conclusion. Our study showed that late-preterm IUGR infants present a significantly higher risk of neonatal complications when compared to late-preterm AGA infants.

[Late preterm infants: A population at underestimated risk]

BACKGROUND AND OBJECTIVE

There has been a gradual rise in prematurity rates recent years, almost exclusively at the expense of the late preterm (34 to 36 weeks). This population, although with less risk than smaller preterm gestational age, has a morbidity rate significantly higher than term infants. However, there is some underestimation regarding developments in the short and long term. The aim of this study was to look at the incidence of prematurity in our institution and to analyze morbidity and mortality in late preterm compared with term infants

SUBJECTS AND METHODS

We performed a retrospective review of newborns in our Hospital from January 1992 until December 31, 2008. Late preterm group was defined as between 34(0/7) and 36(6/7) weeks gestation (N=2003) and term infants from 37 to 42 weeks gestation (N=32015). We formed 2 subgroups according two time periods (1992-1998 and 2000-2008). The morbidity and mortality for each of the groups and subgroups, and the morbidity from week 34 to 42, were analysed and compared.

RESULTS

During the period studied, the prematurity rate increased from 3.9% to 9.8%, exclusively at the expense of the late preterm (79%). The rate of mortality in late preterm was 5 per thousand compared to 1.1 per thousand in the term (P <0.0001, OR 4.71, 95% CI 2.3-9.5). The incidence of admission to the Neonatal Unit, Cesarean rate, twin, respiratory disorders, need for respiratory support in the form of nasal CPAP or mechanical ventilation, incidence of apnea, jaundice requiring phototherapy, hypoglycaemia and need for parenteral nutrition were significantly higher (P<0.0001) in the late preterm group compared with term infants. The morbidity rate decreased significantly as gestational age increased, with the lowest value from 39 weeks.

CONCLUSIONS

Morbidity and mortality in late preterm infants is significantly higher than in term infants. The guidelines for these near term premature babies need to be reviewed, looking for possible causes of prematurity, and trying to reduce their impact, as well as developing a protocol for their care and close monitoring to minimize the associated morbidity. There should be long-term monitoring to find out the consequences on their psychomotor development. The obstetrics group should be made aware of the true risks of births in the near-term gestational ages.

The effect of barusiban, a selective oxytocin antagonist, in threatened preterm labor at late gestational age: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

The objective of the study was to compare barusiban with placebo in threatened preterm labor.

STUDY DESIGN

This was a randomized, double-blind, placebo-controlled, multicenter study. One hundred sixty-three women at 34-35 weeks plus 6 days, and with 6 or more contractions of 30 seconds duration during 30 minutes, cervical length 15 mm or less, and cervical dilatation > 1 and < 4 cm were randomized to a single intravenous bolus of barusiban (0.3, 1, 3, or 10 mg) or placebo. The primary endpoint was percentage of women who did not deliver within 48 hours.

RESULTS

None of the barusiban doses reduced the number of uterine contractions compared with placebo. There was no significant difference in the percentage of women who did not deliver within 48 hours (72% placebo and 65-88% barusiban groups; P = .21-.84). Barusiban was not associated with an adverse safety profile in the woman, fetus, neonate, or infant.

CONCLUSION

An intravenous bolus of barusiban was no more effective than placebo in stopping preterm labor in pregnant women at late gestational age.

Changing patterns of fetal lung maturity testing

OBJECTIVE

In our laboratory, a decrease in fetal lung maturity (FLM) testing on amniotic fluid occurred over a 10-year period, and we desired to determine if this was a national phenomenon and, if present, ascertain possible etiologies.

STUDY DESIGN

Society of Maternal-Fetal Medicine fellows, both in academic centers and private practice, were surveyed with regard to current usage of FLM testing.

RESULT

Of 680 surveys, 417 (61%) responses were returned and 60% noted a decrease in FLM testing (range of reduction--foam stability index 65%, fluorescence polarization 35%, phosphatidyl glycerol 71%, lecithin/sphingomyelin ratio 70%). The most common reason suggested for the decline is that the tests were not needed for patient management.

CONCLUSION

Obstetric patterns of FLM testing have declined, principally in near-term pregnancies, and this could adversely affect neonatal outcome.

"Late-preterm" infants: a population at risk

Late-preterm infants, defined by birth at 34(0/7) through 36(6/7) weeks' gestation, are less physiologically and metabolically mature than term infants. Thus, they are at higher risk of morbidity and mortality than term infants. The purpose of this report is to define "late preterm," recommend a change in terminology from "near term" to "late preterm," present the characteristics of late-preterm infants that predispose them to a higher risk of morbidity and mortality than term infants, and propose guidelines for the evaluation and management of these infants after birth.

Epidemiology of late preterm (near-term) births

The preterm birth rate (births before 37 completed weeks of gestation) has been increasing in the United States, largely driven by an increase in infants delivered between 34 and 36 weeks, often called near-term, but referred to as late preterm in this article. In 2004, the preterm birth rate was 12.5%, the highest rate since the National Center for Health Statistics began tracking such data. This article reviews the epidemiology of late preterm births and proposes a research agenda.

Prevalência e fatores associados à prematuridade entre gestantes submetidas à inibição de trabalho de parto prematuro

OBJETIVOS: identificar a prevalência de parto prematuro em gestantes submetidas ao tratamento de inibição de trabalho de parto prematuro e analisar os fatores associados. MÉTODOS: estudo transversal, com dados coletados de 163 prontuários de gestantes submetidas a tratamento de inibição de trabalho de parto prematuro atendidas em 1995-2000, no Hospital Universitário da Universidade de São Paulo, Brasil. A variável dependente constituiu-se na ocorrência de parto prematuro e as independentes foram: idade, escolaridade, ocupação, paridade, companheiro, tabagismo, infecção urinária prévia, número de consultas pré-natal e intervalo interpartal. A análise foi feita pelo teste de associação pelo Qui-quadrado e modelos de regressão logística univariado e múltiplo. RESULTADOS: 66,3% das gestantes tiveram filhos prematuros e, em 22,7% dos casos, o parto ocorreu antes de 34 semanas. Houve associação estatística significativa entre parto prematuro e ser nulípara e apresentar número baixo de consultas pré-natal. CONCLUSÕES: atenção especial deve ser dada às gestantes nulíparas e com número reduzido de consulta pré-natal submetidas ao tratamento de inibição de trabalho de parto prematuro, com a finalidade de prevenir esse evento.

A recommendation for the definition of "late preterm" (near-term) and the birth weight-gestational age classification system

Determination of gestational age is important to assess risks for morbidity and mortality in neonates. Definitions for preterm, term and postterm have been precisely defined although definitions for subgroups of infants within these categories have not been well defined. More precise definitions for the subgroup of infants born "near-term" is especially important because of the rapid increase in percentage of births attributed to this subgroup. It is recommended that "late preterm" replace "near-term" because it better reflects the higher risk for complications of preterm birth experienced by this subgroup of preterm infants. Furthermore, it is proposed that "late preterm" be defined as beginning on the 239th day (34 0/7 weeks' gestation) and ending on the 259th day (36 6/7 weeks' gestation) since the first day of the mother's last normal menstrual period.

Changes in the gestational age distribution among U.S. singleton births: impact on rates of late preterm birth, 1992 to 2002

There is mounting evidence that infants born late preterm (34-36 weeks) are at greater risk for morbidity than term infants. This article examines the changing epidemiology of gestational length among singleton births in the United States, from 1992 to 2002. Analyzing gestational age by mode of delivery, the distribution of spontaneous births shifted to the left, with 39 weeks becoming the most common length of gestation in 2002, compared with 40 weeks in 1992 (P < 0.001). Deliveries at > or =40 weeks gestation markedly decreased, accompanied by an increase in those at 34 to 39 weeks (P < 0.001). Singleton births with PROM or medical interventions had similar trends. Changes in the distribution of all singleton births differed by race/ethnicity, with non-Hispanic white infants having the largest increase in late preterm births. These observations, in addition to emerging evidence of increased morbidity, suggest the need for investigation of optimal obstetric and neonatal management of these late preterm infants.

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.