Late preterm gestation: physiology of labor and implications for delivery

Factors Associated With Late Prematurity in the University Hospital of Valle Cali, Colombia During 2013-2014

Introduction: The birth rate of late premature babies has been increasing in recent years, composing now 75% of all premature births. This growing trend can be explained by different demographic transformations such as an increase in the demand for infertility treatments, older maternal age and the higher incidence of multiple pregnancies, cesarean sections, and labor induction. These premature babies contribute 30% to the global neonatal mortality rate. Objective: To identify the factors associated with late prematurity at the Hospital Universitario del Valle during the years 2013-2014. Methodology: Case and control design, 424 patients, 212 cases and 212 controls participated. Cases were defined as newborns with gestational age between 34 and 36 weeks and 6 days old. For the analysis, logistic regression models were developed and association forces (OR) were determined. Results: A univariate analysis shows that the proportion of teenage pregnant women corresponds to 22.64%. Bivariate analysis shows the maternal morbidity due to hypertensive disorders was 1.6 times higher (95% CI 1.06-2.63), the obstetric alterations in 2.9 times (CI of 95% 1.56-5.44), late preterm infants require more oxygen support 3.26 times (95% CI 1.76-6.03). After adjusting the model, it was found that late premature infants have a 3-fold probability of requiring some resuscitation maneuver (ORa 3.23 95% CI 2.09-4.99), birth is higher by cesarean section by 4.17 times (ORa 4.17 IC 95% 2.50-6.98), maternal morbidity was higher in 1.37 times (ORa 1.37 95% CI 1.14-1.65). The morbidity of the newborn was greater, close to the statistical significance for late premature infants in 1.26 times (ORa 1.26 95% CI 0.97-1.64). Conclusions: Late premature births in this study show a higher probability of developing morbidity, have a greater opportunity to be born by cesarean section, are products of mothers with morbidity (specifically hypertensive disorders), and require further resuscitation with a need of early obstetric intervention.

Características maternas em gestações com risco de prematuridade tardia

OBJETIVOS: avaliar as características maternas na prematuridade tardia. MÉTODOS: foi realizado um estudo do tipo corte transversal, com análise secundária das gestantes incluídas em um ensaio clínico randomizado realizado no Nordeste do Brasil, no período de 2008 a 2010, entre 34 e 36 semanas. Analisadas as variáveis maternas: idade, paridade, idade gestacional, antecedentes de prematuridade e condições clínicas associadas. A análise estatística foi realizada no programa Epi-Info 3.5.3. Foram construídas tabelas de distribuição de frequência para as variáveis categóricas e calculadas medidas de tendência central e de dispersão para as numéricas. Para determinação da associação entre a frequência das morbidades por estratos de idade gestacional, utilizou-se o teste qui-quadrado de associação. Considerou-se o nível de significância de 5%. RESULTADOS: foram analisadas 273 mulheres no IMIP com risco iminente de prematuridade tardia. A idade média foi 23,1 anos, 28,6% eram adolescentes e 53,8% primíparas. A idade gestacional média foi 35 semanas. Cerca de 12% tinham antecedentes de prematuridade. As condições associadas à prematuridade tardia foram: trabalho de parto prematuro (67%), ruptura prematura das membranas (39,6%), síndromes hipertensivas (25,3%), sem haver diferença da frequência por subgrupos de idade gestacional. CONCLUSÕES: trabalho de parto prematuro espontâneo, ruptura prematura das membranas e síndromes hipertensivas foram as condições clínicas mais frequentemente associadas com prematuridade tardia.

Prenatal counseling beyond the threshold of viability

OBJECTIVE

It is common clinical practice to counsel parents expecting an early-moderate premature birth. The aim of the current study was to assess maternal knowledge of potential problems of prematurity after counseling.

STUDY DESIGN

Prospective study of 49 participants admitted between 23 and 33 weeks gestation with threatened premature birth; a prematurity knowledge questionnaire and the State-Trait Anxiety Inventory were administered after counseling but before delivery.

RESULT

Across all gestational-ages, participants were more aware of short-term problems than long-term problems. With increasing gestational age the knowledge of long-term problems decreased (P=0.01). Maternal knowledge was 82% for gestational ages where clear guidelines exist regarding goal of counseling and information that should be provided to the parents.

CONCLUSION

Most mothers of early-moderate premature infants are not aware of the potential for long-term problems. Guidelines, which outline the information that should be provided to parents, may improve maternal knowledge after counseling.

Early neonatal outcome in late preterms

OBJECTIVES

To study the maternal risk factors, morbidity, mortality of late preterm in comparison to term neonates.

METHODS

This Cohort study involved two hundred fifty consecutively born late preterm and equal number of term newborns delivered in a tertiary care hospital. They were followed till discharge for morbidities and mortality. Detailed maternal and neonatal factors were studied and compared between the two groups.

RESULTS

Late preterm babies constituted 55% of all live preterm births during the study period. The odds of babies developing major morbidity was significantly more in those whose mothers had hypertension and infections (OR 2.69 95% CI: 1.55, 4.68 and 2.08, 95% CI: 1.6, 2.71 respectively). In the study group, 42.4% and 20.8% babies suffered major and minor morbidity compared to 8.4% and 6.8% of term controls respectively. Late preterm neonates had significantly higher odds of developing morbidity like respiratory distress (12.4% vs. 5.6%, OR 2.21, 95%CI 1.21,4.11), need for non invasive(17.3% vs. 5.7%, OR 3.05 95% CI 1.69, 5.47) and invasive ventilation (14.6% vs. 1.7%, OR 8.62, 95% CI 3.09, 24.04), sepsis (20.8% vs. 5.2%, OR 5.20, 95% CI 2.71, 9.99), seizures (22.8% vs. 4.8%, OR 4.75 95%CI 2.61, 8.63), shock (17.6% vs. 4.4%, OR 4.00 95% CI 2.12,7.56), and jaundice (26% vs. 6%, OR 4.33 95%CI 2.54, 7.39). By logistic regression, the odds of developing major morbidity decreased with increasing gestational age (aOR 0.28 95% CI 0.18, 0.45; p < 0.001) and increased with hypertensive disease of pregnancy (aOR 2.16 95% CI 1.09, 4.260; p = 0.026).

CONCLUSIONS

Late preterm neonates have significantly more mortality and morbidity compared to term controls. Maternal hypertension and lower gestational age are the strongest predictors of morbidity.

Late-preterm birth by delivery circumstance and its association with parent-reported attention problems in childhood

OBJECTIVE

Late-preterm birth (LPB, 34-36 wk) has been associated with an increased risk of attention problems in childhood relative to full-term birth (FTB, ≥37 wk), but little is known about factors contributing to this risk. The authors investigated the contributions of clinical circumstances surrounding delivery using follow-up data from the Pregnancy Outcomes and Community Health (POUCH) Study.

METHODS

Women who delivered late preterm or full term and completed the sex- and age-referenced Conners' Parent Rating Scales-Short Form: Revised were included in the present analysis (N = 762; children's age, 3-9 y). The Conners' Parent Rating Scales-Short Form: Revised measures dimensions of behavior linked to attention problems, including oppositionality, inattention, hyperactivity, and a global attention problem index. Using general linear models, the authors evaluated whether LPB subtype (medically indicated [MI] or spontaneous) was associated with these dimensions relative to FTB.

RESULTS

After adjustment for parity, sociodemographics, child age, and maternal symptoms of depression and serious mental illness during pregnancy and at the child survey, only MI LPB was associated with higher hyperactivity and global index scores (mean difference from FTB = 3.8 [95% confidence interval {CI}: 0.5, 7.0] and 3.1 [95% CI 0.0, 6.2]). These findings were largely driven by children between 6 and 9 years. Removal of women with hypertensive disorders during pregnancy (N = 85) or placental findings related to hypertensive conditions (obstruction, decreased maternal spiral artery conversion; N = 134) reduced the differences below significance thresholds.

CONCLUSIONS

Among LPBs, only MI LPB was associated with higher levels of parent-reported childhood attention problems, suggesting that complications motivating medical intervention during the late-preterm period mark increased risk for such problems. Hypertensive disorders seem to play a role in these associations.

Obstetric management of moderate and late preterm labour

Moderate and late preterm births account for the majority of preterm babies. The common perception that birth at 32-36 weeks' gestation carries few risks is now being challenged, as these babies have increased risk of neonatal mortality and morbidity. However, spontaneous labour at this gestation frequently has no specific, easily identifiable precursor, although preterm birth per se has a number of epidemiological and clinical associations. Prediction and prevention of preterm birth is currently largely aimed at identifying women at high risk such as those with previous preterm birth, and targeting intervention at this group. Both cervical length assessment and fibronectin testing permit some modification of the likelihood of preterm birth in this group. Progesterone treatment for the prevention of preterm birth is currently being researched widely, and appears a potentially promising strategy. Babies born at 32-36 weeks' gestation need careful monitoring in labour, with modification of intervention in labour due to their prematurity.

Morbidity and mortality in late preterm and early term newborns: a continuum

Late preterm and early term infants are at higher risk for short-term and long-term morbidities and mortality than term infants. Such outcomes are influenced by many factors, the strongest of which is gestational age. Counseling and educating women and families about risks of late preterm and early term births is helpful for timing and route of delivery, managing the pregnancy and infant, and prognosticating outcomes for infants.

Physical activity and preterm birth: a literature review

Preterm birth is a major reason for infant mortality and morbidity, representing a public health concern worldwide. Regular and voluntary physical activity is healthy behaviour that should be incorporated by everyone, including pregnant women. On the other hand, some women are exposed to highly demanding occupational physical activities during pregnancy that might represent a threat to the fetus and to their own health. This paper is a literature review of studies (1987-2007) on physical activity during pregnancy and its relationship to preterm birth. Although the effects measured by the studies are not strong and the evidence is impaired by many methodological flaws, it seems that recreational or leisure-time physical activities performed regularly provide protection against prematurity. Studies on occupational physical activities, especially standing for long periods, present contrasting results - some presenting standing as a risk factor, but most showing no association. Housework and other daily activities do not seem to be associated with preterm birth. Regardless of the methodological aspects of the studies reviewed, there is a chance that the real effect of occupational physical activity is being blurred by some underlying factors not easily measured in epidemiological investigations. Our conclusions do not reject the idea that working conditions might represent danger for the pregnancy outcome, but only raise the question that maybe the mechanisms through which employment-related physical activities have been considered up till now could be better and more thoroughly studied. Future studies should pay additional attention to psychological and socioeconomic characteristics, without neglecting biological plausibility.

Perinatal outcomes associated with preterm birth at 33 to 36 weeks' gestation: a population-based cohort study

OBJECTIVE

The aim of our population-based study was to compare the mortality and morbidity of late-preterm infants to those born at term. Advancement in the care of extremely preterm infants has led to a shift of focus away from the more mature preterms, who are being managed as "near terms" and treated as "near normal." Some recent studies have suggested an increased risk of mortality and morbidity in this group compared with infants born at term. However, there are few population-based mortality and morbidity statistics for this cohort, particularly reflecting current practice.

METHODS

Using data from the British Columbia Perinatal Database Registry we analyzed all singleton births between 33 and 40 weeks' gestation from April 1999 to March 2002 in the province of British Columbia, Canada. We divided this birth cohort into late preterm (33-36 weeks, n = 6381) and term (37-40 weeks, n = 88 867) groups. We compared mortality and morbidity data and associated maternal factors between the 2 groups.

RESULTS

Stillbirth rate and perinatal, neonatal, and infant mortality rates were significantly higher in the late-preterm group. Infants in this group needed resuscitation at birth more frequently than those in the term group. Late-preterm infants had a significantly higher incidence of respiratory morbidity and infection and had a significantly longer duration of hospital stay. Maternal factors that were more common in the late-preterm group included chorioamnionitis, hypertension, diabetes, thrombophilia, prelabor rupture of membranes, primigravida, and teenage pregnancy.

CONCLUSIONS

Our data support recent literature regarding neonatal mortality and morbidity in late-preterm infants and warrants a review of care for this group at the local, national, and global levels. Reorganization of services and increased resource allocation may be needed in most hospitals and community settings to achieve optimization of care for this group of infants.

Resuscitative procedures at birth in late preterm infants

OBJECTIVE

Evaluate the need for resuscitative procedures at birth, in late prematures.

STUDY DESIGN

This prospective cohort study enrolled all liveborn infants from 1 to 30 September 2003, with 34 to 41 weeks of gestation without congenital anomalies, born in 35 public hospitals of 20 Brazilian state capitals. Logistic regression analyzed variables associated with the need for bag and mask ventilation.

RESULT

Of the 10 774 infants studied, 1054 were late preterms and 485 required resuscitative measures. Of the 1054, 338 (32%) received only free-flow oxygen, 143 (14%) were bag and mask ventilated, 27 (3%) were intubated and 10/27 received chest compressions and/or medications. Bag and mask ventilation in late preterms was associated with twin gestation, maternal hypertension, nonvertex presentation, cesarean delivery and lower gestational age.

CONCLUSION

Improving control of maternal hypertension, prolonging gestation for 1 to 2 weeks and restricting operative deliveries could decrease the need of resuscitation of late preterms at birth.