Epidemiology of moderate preterm, late preterm and early term delivery

Fetal inflammation associated with minimal acute morbidity in moderate/late preterm infants

OBJECTIVE

To determine whether exposure to acute chorioamnionitis and fetal inflammation caused short-term adverse outcomes.

DESIGN

This is a prospective observational study: subjects were mothers delivering at 32-36 weeks gestation and their preterm infants at a large urban tertiary level III perinatal unit (N=477 infants). Placentae and fetal membranes were scored for acute histological chorioamnionitis based on the Redline criteria. Fetal inflammation was characterised by histological diagnosis of funisitis (umbilical cord inflammation), increased cord blood cytokines measured by ELISA, and activation of the inflammatory cells infiltrating the placenta and fetal membranes measured by immunohistology. Maternal and infant data were collected.

RESULTS

Twenty-four per cent of 32-36-week infants were exposed to histological chorioamnionitis and 6.9% had funisitis. Immunostaining for leucocyte subsets showed selective infiltration of the placenta and fetal membranes with activated neutrophils and macrophages with chorioamnionitis. Interleukin (IL) 6, IL-8 and granulocyte colony-stimulating factor were selectively increased in the cord blood of preterm infants with funisitis. Compared with infants without chorioamnionitis, funisitis was associated with increased ventilation support during resuscitation (43.8% vs 15.4%) and more respiratory distress syndrome postnatally (27.3% vs 10.2%) in univariate analysis. However, these associations disappeared after adjusting for prematurity.

CONCLUSIONS

Despite fetal exposure to funisitis, increased cord blood cytokines and activated placental inflammatory cells, we could not demonstrate neonatal morbidity specifically attributable to fetal inflammation after adjusting for gestational age in moderate and late preterm infants.

Perinatal outcome in pregnancies complicated with gestational diabetes mellitus and very preterm birth: case-control study

Preterm birth is defined as all births before 37 completed weeks of gestation. Preterm birth can be further sub-divided based on gestational age: extremely preterm (<28 weeks), very preterm (28 to <32 weeks) and moderate preterm (32 to <37 weeks). Retrospective observational case-control study review (1 year i.e., 2015) is to assess pregnancy outcome among women with gestational diabetes mellitus (GDM) delivering very preterm (28 + 0/7 to 31 + 6/7 weeks of gestation). The study group included all women diagnosed with GDM and were compared to a control group of women delivering at the same gestational age period but without GDM. In all, 30 women were included in the study, of whom 15 were diagnosed with GDM and 15 were not. All women had a cesarean delivery. Neonates of mothers with GDM had higher ponderal index. Birth weight had the positive associations with blood glucose of newborn (r = 0.37, p = 0.047) and term of births (r = 0.52, p = 0.003). Birth weight had the negative associations with maternal systolic pressure (r = -0.7, p < 0.05), pre-eclampsia (r = -0.6, p < 0.05) and maternal pre-pregnancy body mass index (r = -0.5, p < 0.05). There were no differences in mortality or other parameters for neonatal morbidity, including bronchopulmonary dysplasia, prematurity retinopathy, neonatal anemia. According to our data, very preterm delivery occurring in women with GDM does not confer an increased risk for neonatal complications.

Risk of developmental delay: Comparison of late preterm and full term Canadian infants at age 12 months

BACKGROUND

Late preterm (34(0/7) to 36(6/7)weeks gestation) infants may experience developmental delays greater than those found in term (≥ 37(0/7)weeks gestation) infants.

AIM

The aim of this study was to compare the risk of developmental delay between late preterm and full-term Canadian born infants at age 12months, and to determine infant and maternal factors associated with risk of delay.

METHODS

A descriptive comparative study was conducted from data available from the All Our Babies community-based, prospective, pregnancy cohort in Calgary, Alberta. Participants were a sample of mothers of 52 infants born late preterm and 156 randomly selected mothers of term infants, matched for infant sex; eligible infants were singleton births. Mothers completed a developmental screening tool, the Ages and Stages Questionnaire, version 3 (ASQ-3), when their infant was age 12months. Corrected age (CA) was used for preterm infants.

RESULTS

Both late preterm and term infants who required neonatal intensive care (NICU) were more likely to demonstrate risk of developmental delay. Compared to term infants, there was a trend for late preterm infants to be at risk of communication and gross motor delay at age 12months CA that was attenuated to the null when adjustments were made for NICU admission and other covariates.

CONCLUSIONS

Infants born between 34 and 41weeks who are admitted to NICU are at increased risk of developmental delay. Early identification of risk provides an opportunity for referral for developmental assessment and early intervention programming.

Is maternal trait anxiety a risk factor for late preterm and early term deliveries?

Background

Anxiety is associated with preterm deliveries in general (before week 37 of pregnancy), but is that also true for late preterm (weeks 34/0–36/6) and early term deliveries (weeks 37/0–38/6)? We aim to examine this association separately for spontaneous and provider-initiated deliveries.

Methods

Participants were pregnant women from the Norwegian Mother and Child Cohort Study (MoBa), which has been following 95 200 pregnant women since 1999. After excluding pregnancies with serious health complications, 81 244 participants remained. National ultrasound records were used to delineate late preterm, early term, and full-term deliveries, which then were subdivided into spontaneous and provider-initiated deliveries. We measured trait anxiety based on two ratings of the anxiety items on the Symptom Checklist-8 (Acta Psychiatr Scand 87:364–7, 1993). Trait anxiety was transformed into categorizing the score at the mean and at ± 2 standard deviations.

Results

Trait anxiety was substantially associated with late preterm and early term deliveries after adjusting for confounders. In the whole sample, women with the highest anxiety scores (+2 standard deviations) were more likely [(odds ratio (OR) = 1.7; 95 % confidence-interval (CI) 1.3-2.0)] to delivering late preterm than women with the lowest anxiety scores. Their odds of delivering early term were also high (OR = 1.4; CI 1.3-1.6). Women with spontaneous deliveries and the highest anxiety scores had higher odds (OR = 1.4; CI 1.1-1.8) of delivering late preterm and early term (OR = 1.3; CI = 1.3-1.5). The corresponding odds for women with provider-initiated deliveries were OR = 1.7 (CI = 1.2-2.4) for late preterm and OR = 1.3 for early term (CI = 1.01-1.6). Irrespective of delivery onset, women with provider-initiated deliveries had higher levels of anxiety than women delivering spontaneously. However, women with high anxiety were equally likely to have provider-initiated or spontaneous deliveries.

Conclusions

This study is the first to show substantial associations between high levels of trait anxiety and late preterm delivery. Increased attention should be given to the mechanism underlying this association, including factors preceding the pregnancy. In addition, acute treatment should be offered to women displaying high levels of anxiety throughout pregnancy to avoid suffering for the mother and the child.

The transition from intra to extra-uterine life in late preterm infant: a single-center study

BACKGROUND

Infants born at 34 to 36 weeks of gestation (late preterm) are at greater risk for adverse outcomes than those born at 37 weeks of gestation or later. Aim of this paper is to examine risk factors for late preterm births and to investigate the complications of the transition period in late preterm infants (LPIs).

METHODS

All consecutive late preterm deliveries, excluded stillbirths, were included. Maternal and neonatal data, need for delivery room resuscitative procedures, temperature at birth (T1) and two hours after the admission (T2) were analyzed in all LPIs stratified by Gestational Age (GA) and divided into three groups (34, 35 and 36 weeks).

RESULTS

Two hundred seventy-six LPIs were analyzed. Pregnancy complications were present in 72 mothers (26.1 %), more frequently at 34 weeks of gestation respect to 35 and 36 weeks (p = 0.008, p = 0.006 respectively). Forty seven LPIs (17.1 %) needed for any resuscitation and 37 (13.4 %) were ventilated at birth. LPIs at 34 weeks were significantly more likely to receive ventilation respect to those at 35 and 36. At T1 the mean temperature resulted lower at 34 weeks respect to 36 weeks (p = 0.03). At T2 respect to T1, the rate of normothermic neonates increased at 35 and 36 weeks (p = 0.003, p = 0.005, respectively). Hypoglicemia rate was similar among the groups; 66.7 % of hypoglicemic neonates were hypothermic at T1. The rate of respiratory diseases and NICU admission decreased with increasing GA. Higher number of neonates ventilated at birth developed respiratory disorders respect to those unventilated (40.5 % vs 8.4 %; p < 0.001).

CONCLUSIONS

Transition period in LPIs may become critical, as resuscitation strategies can be required and heat loss can occur. LPIs, especially at 34 gestational weeks, are higher-risk group needing adequate and targeted management at birth.

Pulmonary Morbidity in Infancy after Exposure to Chorioamnionitis in Late Preterm Infants

RATIONALE

Chorioamnionitis is an important cause of preterm birth, but its impact on postnatal outcomes is understudied.

OBJECTIVES

To evaluate whether fetal exposure to inflammation is associated with adverse pulmonary outcomes at 6 to 12 months' chronological age in infants born moderate to late preterm.

METHODS

Infants born between 32 and 36 weeks' gestational age were prospectively recruited (N = 184). Chorioamnionitis was diagnosed by placenta and umbilical cord histology. Select cytokines were measured in samples of cord blood. Validated pulmonary questionnaires were administered (n = 184), and infant pulmonary function testing was performed (n = 69) between 6 and 12 months' chronological age by the raised volume rapid thoracoabdominal compression technique.

MEASUREMENTS AND MAIN RESULTS

A total of 25% of participants had chorioamnionitis. Although infant pulmonary function testing variables were lower in infants born preterm compared with historical normative data for term infants, there were no differences between infants with chorioamnionitis (n = 20) and those without (n = 49). Boys and black infants had lower infant pulmonary function testing measurements than girls and white infants, respectively. Chorioamnionitis exposure was associated independently with wheeze (odds ratio [OR], 2.08) and respiratory-related physician visits (OR, 3.18) in the first year of life. Infants exposed to severe chorioamnionitis had increased levels of cord blood IL-6 and greater pulmonary morbidity at age 6 to 12 months than those exposed to mild chorioamnionitis. Elevated IL-6 was associated with significantly more respiratory problems (OR, 3.23).

CONCLUSIONS

In infants born moderate or late preterm, elevated cord blood IL-6 and exposure to histologically identified chorioamnionitis was associated with respiratory morbidity during infancy without significant changes in infant pulmonary function testing measurements. Black compared with white and boy compared with girl infants had lower infant pulmonary function testing measurements and worse pulmonary outcomes.

Late preterm birth in the far south of Brazil: a population based study

Abstract Objectives: to describe the prevalence of late preterm birth (LPB) and identify factors associated with its occurrence in the municipality of Rio Grande, RS. Methods: a standardized questionnaire was applied to allpuerperal women resident in the municipality who had children in theyear 2013. Preterm birth was defined as birth occur-ring between the 34th and 36th week of gestation, preferably evaluated by means of ultra-sonography in the 6th to 20th weeks. The analysis used Poisson regression with robust adjustment of variance, following the hierarchical model.The effect measure used was the preva-lence ratio (PR). Results: of the 2286 births included in the study, 11.8% (CI95%: 10.5-13.1) were LPBs. After adjusted analysis, the PRfor occurrence of LPB among black-skinned motherswas 1.40 (1.01-1.96) in relation to white-skinned women; 1.74 (1.23-2.45) among those who attended less than sixprenatal consults compared to those who attended nine or more; the PR was 1.36 (1.11-1.68) for those classified as depressives compared to others and 1.29 (1.01-1.65) for those undergoing caesarian. Conclusions: the results suggest the existence of inequality in relation to skin color and the important impact of the number ofprenatal consults on the outcome. More appropriately designed studies are needed to confirm the causal relation among maternal depression, caesarian and LPB.

The respiratory consequences of early-term birth and delivery by caesarean sections

In England and Wales, 19% of live births in 2012 were at 37-38 weeks' gestation, equating to nearly 140 000 early-term births each year. Since caesarean sections (CS) are often performed at early-term gestations, this accounts for some of the increased proportion of the early-term births. Infants born early-term are at an increased risk of neonatal respiratory morbidity particularly if they are delivered by caesarean section. The long term lung function data are limited but available data suggest that early-term delivery is associated with respiratory morbidity in childhood. CS also appears to be associated with increased neonatal morbidity and future development of respiratory symptoms. However, future studies need to confirm the independent effects of caesarean sections and early-term deliveries particularly for long term outcomes as both are likely to affect the respiratory system differently.

The clinical use of corticosteroids in pregnancy

BACKGROUND

The use of antenatal steroid therapy is common in pregnancy. In early pregnancy, steroids may be used in women for the treatment of recurrent miscarriage or fetal abnormalities such as congenital adrenal hyperplasia. In mid-late pregnancy, the antenatal administration of corticosteroids to expectant mothers in anticipation of preterm birth is one of the most important advances in perinatal medicine; antenatal corticosteroids are now standard care for pregnancies at risk of premature delivery in high- and middle-income countries. The widespread uptake of this therapy is due to a compelling body of evidence demonstrating improved neonatal outcomes following antenatal corticosteroid exposure, stemming most notably from corticosteroid-driven maturation of fetal pulmonary function. As we approach the 50th anniversary of landmark work in this area by Liggins and Howie, it is apparent that much remains to be understood with regards to how we might best apply antenatal corticosteroid therapy to improve pregnancy outcomes at both early and mid to late gestation.

METHODS

Drawing on advances in laboratory science, pre-clinical and clinical studies, we performed a narrative review of the scientific literature to provide a timely update on the benefits, risks and uncertainties regarding antenatal corticosteroid use in pregnancy. Three, well-established therapeutic uses of antenatal steroids, namely recurrent miscarriage, congenital adrenal hyperplasia and preterm birth, were selected to frame the review.

RESULTS

Even the most well-established antenatal steroid therapies lack the comprehensive pharmacokinetic and dose-response data necessary to optimize dosing regimens. New insights into complex, tissue-specific corticosteroid signalling by genomic-dependent and independent mechanisms have not been used to inform corticosteroid treatment strategies. There is growing evidence that some fetal corticosteroid treatments are either ineffective, or may result in adverse outcomes, in addition to lasting epigenetic changes in a variety of homeostatic mechanisms. Nowhere is the need to better understand the intricacies of corticosteroid therapy better conveyed than in the findings of Althabe and colleagues who recently reported an increase in overall neonatal mortality and maternal morbidity in association with antenatal corticosteroid administration in low-resource settings.

CONCLUSIONS

New research to clarify the benefits and potential risks of antenatal corticosteroid therapy is urgently needed, especially with regard to corticosteroid use in low-resource environments. We conclude that there is both significant scope and an urgent need for further research-informed refinement to the use of antenatal corticosteroids in pregnancy.

Strain at the internal cervical os assessed with quasi-static elastography is associated with the risk of spontaneous preterm delivery at ≤34 weeks of gestation

AIM

To evaluate the association between cervical strain assessed with quasi-static elastography and spontaneous preterm delivery.

METHODS

Quasi-static elastography was used to estimate cervical strain in 545 pregnant women with singleton pregnancies from 11 weeks to 28 weeks of gestation. Cervical strain was evaluated in one sagittal plane and in the cross-sectional planes of the internal cervical os and external cervical os. The distribution of strain values was categorized into quartiles for each studied region and their association with spontaneous preterm delivery at ≤34 weeks and at <37 weeks of gestation was evaluated using logistic regression.

RESULTS

The prevalence of spontaneous preterm delivery at <37 weeks of gestation was 8.2% (n=45), and that at ≤34 weeks of gestation was 3.8% (n=21). Strain in the internal cervical os was the only elastography value associated with spontaneous preterm delivery. Women with strain values in the 3rd and 4th quartiles had a significantly higher risk of spontaneous preterm delivery at ≤34 weeks and at <37 weeks of gestation when compared to women with strain values in the lowest quartile. When adjusting for a short cervix (<25 mm) and gestational age at examination, women with strain values in the 3rd quartile maintained a significant association with spontaneous preterm delivery at ≤34 weeks (OR 9.0; 95% CI, 1.1-74.0; P=0.02), whereas women with strain values in the highest quartile were marginally more likely than women with lowest quartile strain values to deliver spontaneously at ≤37 weeks of gestation (OR 95% CI: 2.8; [0.9-9.0]; P=0.08).

CONCLUSION

Increased strain in the internal cervical os is associated with higher risk of spontaneous preterm delivery both at ≤34 and <37 weeks of gestation.

Preterm Birth and Adult Wealth: Mathematics Skills Count

Each year, 15 million babies worldwide are born preterm. Preterm birth is associated with adverse neurodevelopmental outcomes across the life span. Recent registry-based studies suggest that preterm birth is associated with decreased wealth in adulthood, but the mediating mechanisms are unknown. This study investigated whether the relationship between preterm birth and low adult wealth is mediated by poor academic abilities and educational qualifications. Participants were members of two British population-based birth cohorts born in 1958 and 1970, respectively. Results showed that preterm birth was associated with decreased wealth at 42 years of age. This association was mediated by decreased intelligence, reading, and, in particular, mathematics attainment in middle childhood, as well as decreased educational qualifications in young adulthood. Findings were similar in both cohorts, which suggests that these mechanisms may be time invariant. Special educational support in childhood may prevent preterm children from becoming less wealthy as adults.

Early-term birth is a risk factor for wheezing in childhood: A cross-sectional population study

BACKGROUND

Early term-born (37-38 weeks' gestation) infants have increased respiratory morbidity during the neonatal period compared with full term-born (39-42 weeks' gestation) infants, but longer-term respiratory morbidity remains unclear.

OBJECTIVE

We assessed whether early term-born children have greater respiratory symptoms and health care use in childhood compared with full term-born children.

METHODS

We surveyed 1- to 10-year-old term-born children (n = 13,361). Questionnaires assessed respiratory outcomes with additional data gathered from national health databases.

RESULTS

Of 2,845 eligible participants, 545 were early term-born and 2,300 were full term-born. Early term-born children had higher rates of admission to the neonatal unit (odds ratio [OR], 1.7; 95% CI, 1.2-2.5) and admission to the hospital during their first year of life (OR, 1.6; 95% CI, 1.2-2.1). Forty-eight percent of early term-born children less than 5 years old reported wheeze ever compared with 39% of full term-born children (OR, 1.5; 95% CI, 1.1-1.9), and 26% versus 17% reported recent wheezing (OR, 1.7; 95% CI, 1.3-2.4). Early term-born children older than 5 years reported higher rates of wheeze ever (OR, 1.4; 95% CI, 1.05-1.8) and recent wheezing over the last 12 months than full-term control subjects (OR, 1.4; 95% CI, 1.02-2.0). Increased rates of respiratory symptoms in early term-born children persisted when family history of atopy and delivery by means of cesarean sections were included in logistic regression models.

CONCLUSION

Early term-born children had significantly increased respiratory morbidity and use of health care services when compared with full term-born children, even when stratified by mode of delivery and family history of atopy.

Post-term birth as a response to environmental stress : The case of September 11, 2001

Background and objectives: Despite growing interest in the role of maternal psychosocial stress as a determinant of preterm birth, no existing work has examined the relation between maternal stress and post-term birth (≥42 weeks). We hypothesize that prolonging gestation past term may represent an adaptive strategy to a suboptimal environment.

Methodology: We examined the relationship between exposure to the September 2001 terrorist attacks and odds of post-term birth in California. We calculated the expected odds of post-term birth among conception cohorts of singleton gestations in California between October 1996 and November 2005. We used time series analysis to test for higher than expected odds of post-term birth among the 10 cohorts exposed to the attacks of September 2001 (those conceived from December 2000 to September 2001).

Results: The observed odds of post-term delivery among gestations at 33–36 weeks in September 2001 were higher than statistically expected for all race/ethnic and sex groups.

Conclusions and implications: Our finding that odds of post-term birth were higher than expected among pregnancies exposed to the September 2001 terrorist attacks in late gestation provides initial support for the hypothesis that exposure to a psychosocial stress during pregnancy may result in prolonged gestation.

Effect of chorioamnionitis on regulatory T cells in moderate/late preterm neonates

Regulatory T-cells (Treg) have a protective role for the control of immune activation and tissue damage. The effects of chorioamnionitis (chorio) on Treg in moderate/late preterm newborns are not known. We hypothesized that infants exposed to chorio would have decreased Treg frequency and/or function. We isolated mononuclear cells from adult peripheral blood and cord blood from term and moderate/late preterm infants who were classified for severity of chorio exposure. Mononuclear cells were analyzed by flow cytometry for Treg frequency and phenotype. Treg suppression of activation of conventional T-cells (Tcon) was also quantified. Treg frequencies were similar in all groups of neonates, but lower than that found in adults. Newborn Treg had a naïve phenotype, with decreased levels of CD45RO, HLA-DR, CD39 and TIGIT compared to adult Treg and chorio did not affect the phenotype. Treg from preterm newborns exposed to severe chorio had higher expression of Ki67 compared to the other groups. Treg from preterm newborns were less suppressive than Treg from adults or term, and the level of suppression was reduced with severe chorio. Relative to term, Treg frequency and phenotype were not affected by prematurity and chorio but their functionality was decreased. Lower Treg activity may contribute to inflammation in newborns that is often associated with chorioamnionitis.

Low birth weight in São Luís, northeastern Brazil: trends and associated factors

BACKGROUND

To analyze trends in LBW (low birth weight) rate using birth registry data and identify factors associated with LBW in São Luís comparing two birth cohorts separated by a 12-year interval.

METHODS

2,426 births were included in 1997/98 and 5,040 in 2010. The dependent variable was LBW (<2,500 g). Multiple logistic regression was performed to determine the association of independent variables with LBW. Data were also obtained from SINASC (Brazilian National Birth Registry) to analyze stillbirth and LBW rates trends from 1996 to 2010, using 3-year moving averages.

RESULTS

LBW, intrauterine growth restriction (IUGR) and preterm birth rates did not differ between the two cohorts. Despite this, birth registry data showed increasing LBW rate up to 2001, coinciding with decreasing stillbirth rate. Both stillbirth and LBW rates decreased thereafter. A significant reduction was observed in the percentage of teenage mothers, mothers with up to 4 years of education, family income up to one minimum wage and mothers who did not attend prenatal care. There was an increase in maternal age ≥35 years and schooling ≥12 years. The variables associated with LBW in 1997/98 were young maternal age (<18 years), maternal smoking during pregnancy and primiparity. Variables that remained in the adjusted model in 2010 were female gender, income <3 minimum wages, lack of prenatal care, maternal smoking during pregnancy and primiparity.

CONCLUSIONS

Although LBW rate did not differ between the two cohorts, this apparent stability masked an increase up to 2001 and a decrease thereafter. The rise in LBW rate paralleled reduction in the stillbirth rate, suggesting improvement in obstetrical and newborn care. Maternal, socioeconomic and demographic factors associated with LBW differed between the two cohorts, except for smoking during pregnancy and parity that were significantly associated with LBW in both cohorts.