Maternal risk factors and obstetric complications in late preterm prematurity

Management of preterm labor: Clinical practice guideline and recommendation by the WAPM-World Association of Perinatal Medicine and the PMF-Perinatal Medicine Foundation

This practice guideline follows the mission of the World Association of Perinatal Medicine in collaboration with the Perinatal Medicine Foundation, bringing together groups and individuals throughout the world, with the goal of improving the management of preterm labor. In fact, this document provides further guidance for healthcare practitioners on the appropriate use of examinations with the aim to improve the accuracy in diagnosing preterm labor and allow timely and appropriate administration of tocolytics, antenatal corticosteroids and magnesium sulphate and avoid unnecessary or excessive interventions. Therefore, it is not intended to establish a legal standard of care. This document is based on consensus among perinatal experts throughout the world in the light of scientific literature and serves as a guideline for use in clinical practice.

Associations between Phthalate Exposure and Gestational Age at Delivery in a Diverse Pregnancy Cohort

The association between prenatal phthalate exposure and late preterm birth (LPTB) is unclear. We examined singleton pregnancies (2006-2011) from a racially and socioeconomically diverse sample of women in the CANDLE cohort of the ECHO-PATHWAYS Consortium. Urine collected in the second and third trimester was analyzed for 14 phthalate metabolites. Multivariate logistic and linear regressions were performed for LPTB, defined as delivery 34-37 weeks, and gestational week, respectively. Models were controlled for socio-demographics, behavioral factors, clinical measurements, medical history, and phthalates in the other trimester. Effect modification by race and pregnancy stress, indicated by intimate partner violence (IPV), was investigated. We conducted a secondary analysis in women with spontaneous preterm labor. The rate of LPTB among 1408 women (61% Black, 32% White) was 6.7%. There was no evidence of decreased gestational age (GA) in association with any phthalate metabolite. Each two-fold increase in third trimester mono-benzyl phthalate (MBzP) was associated with 0.08 weeks longer gestational age (95% CI: 0.03, 0.12). When restricting to women with spontaneous labor, second trimester mono-n-butyl phthalate (MBP) was associated with 54% higher odds (95% CI: 2%, 132%) of LPTB. Associations were not modified by maternal race or IPV exposure. In conclusion, we observed mixed evidence concerning our hypothesis that prenatal phthalate exposure increases risk of LPTB, though secondary analyses suggest increased risk of spontaneous LPTB associated with MBP, which is consistent with a recent pooled analysis of 16 cohorts.

Preterm Labor: A Comprehensive Review of Guidelines on Diagnosis, Management, Prediction and Prevention

Importance

Preterm labor (PTL) is one of the most common and serious pregnancy complications associated with significant perinatal morbidity and mortality, as well as long-term neurologic impairment in the offspring.

Objective

The aim of this study was to review and compare the most recently published major guidelines on diagnosis, management, prediction, and prevention of this severe complication of pregnancy.

Evidence Acquisition

A descriptive review of guidelines from the National Institute for Health and Care Excellence (NICE), the World Health Organization, the American College of Obstetricians and Gynecologists, the New South Wales Government, and the European Association of Perinatal Medicine (EAPM) on PTL was carried out.

Results

There is a consensus among the reviewed guidelines that the diagnosis of PTL is based on clinical criteria, physical examination, measurement of cervical length (CL) with transvaginal ultrasound (TVUS) and use of biomarkers, although there is disagreement on the first-line diagnostic test. The NICE and the EAPM are in favor of TVUS CL measurement, whereas the New South Wales Government mentions that fetal fibronectin testing is the mainstay for PTL diagnosis. Moreover, there is consistency among the guidelines regarding the importance of treating PTL up to 34 weeks of gestation, to delay delivery for 48 hours, for the administration of antenatal corticosteroids, magnesium sulfate, and in utero transfer to higher care facility, although several discrepancies exist regarding the tocolytic drugs of choice and the administration of corticosteroids and magnesium sulfate after 34 and 30 gestational weeks, respectively. Routine cesarean delivery in case of PTL is unanimously not recommended. Finally, the NICE, the American College of Obstetricians and Gynecologists, and the EAPM highlight the significance of screening for PTL by TVUS CL measurement between 16 and 24 weeks of gestation and suggest the use of either vaginal progesterone or cervical cerclage for the prevention of PTL, based on specific indications. Cervical pessary is not recommended as a preventive measure.

Conclusions

Preterm labor is a significant contributor of perinatal morbidity and mortality with a substantial impact on health care systems. Thus, it seems of paramount importance to develop consistent international practice protocols for timely diagnosis and effective management of this major obstetric complication and subsequently improve pregnancy outcomes.

The Effects of Preterm Birth on Musculoskeletal Health-Related Disorders

Preterm birth is associated with various diseases and conditions which demand multidisciplinary medical care. Approximately 10% of all neonates are born prematurely with an increasing survival rate in almost all Western countries. This ongoing, yet desirable trend is creating new challenges for sufficient medical treatment regimens, which should be upheld throughout the patients’ lives. Orthopedic surgeons are focused on musculoskeletal disorders and the improvement of patients’ ability to cope with the challenges of everyday life. The most common conditions associated with preterm birth are cerebral palsy and a dysregulation of the calcium/phosphorus metabolism, which may lead to fractures. These diseases may vary greatly in their organic manifestation and clinical presentation. This demands multidisciplinary cooperation and parental support. Clinical management is aimed on the early enhancement of a patient’s physical, as well as neurological condition, and to prevent the development of secondary musculoskeletal disorders. In this article, we give an overview of the current literature on the most common musculoskeletal disorders associated with preterm birth and critically discuss state of the art diagnostic standards and treatment algorithms.

Preterm births in Iceland 1997-2016: Preterm birth rates by gestational age groups and type of preterm birth

BACKGROUND

The frequency of preterm births has been increasing globally, mainly due to a rise in iatrogenic late preterm births. The aim of this study was to assess the prevalence of preterm births in Iceland during 1997-2016 by type of preterm birth.

METHODS

This study included all live births in Iceland during 1997-2016 identified from the Icelandic Medical Birth Registry. Risk of preterm birth by time period was assessed with Poisson regression models adjusted for demographic variables and indications for iatrogenic births.

RESULTS

The study population included 87 076 infants, of which 4986 (5.7%) were preterm. The preterm birth rate increased from 5.3% to 6.1% (adjusted rate ratio [ARR] = 1.16, confidence interval [CI] = 1.07-1.26) between 1997-2001 and 2012-2016 overall. The increase was only evident in multiples (ARR 1.41, 95% CI 1.21-1.65), not singletons (1.07, 0.97-1.19). The rate of late preterm births (34-36 weeks) increased significantly (1.24, 1.14-1.40), and the rate of iatrogenic preterm births more than doubled during this period even after adjustment for identified medical indications (2.40, 2.00-2.88). The rate of spontaneous preterm births decreased during the study period (0.63, 0.55-0.73), and the rate of PPROM increased (1.31, 1.09-1.57). The most common contributing indications for iatrogenic births were fetal distress (26.2%), hypertensive disorders (18.2%), and severe preeclampsia (16.9%).

CONCLUSIONS

Preterm birth rates increased in multiples in Iceland between 1997 and 2016, and late and iatrogenic preterm births increased overall. The increase in iatrogenic preterm births remained significant after adjusting for medical indications, suggesting that other factors might be affecting the rise.

Optimal time of delivery to reduce the risk of infant mortality in small and normally grown fetuses: A national cohort study in Korea

Purpose

To examine the competing risks of stillbirth versus infant death and to evaluate the optimal time of delivery in the population of small for gestational age (SGA) and non-SGA late preterm and term fetuses.

Methods

This was a retrospective national cohort study of all singleton births between 34 0/7 and 42 6/7 weeks of gestation using the Korean vital statistics (n = 2,106,159). We compared the risk of infant mortality with a composite of fetal–infant mortality risk that would occur after expectant management for one additional week and evaluated the optimal time of delivery, in SGA and non-SGA pregnancies.

Results

In the total population, the risk of expectant management became significantly higher than the risk of delivery, at 39 weeks and beyond, similar with non-SGA group. In the SGA group, the risk of stillbirth was significantly greater at all GAs than for non-SGA pregnancies, and the risk of infant death was significantly increased until 38 weeks (25.8 per 10,000 live births, 95% CI 20.11–32.47), and the risk of stillbirth was significantly increased at 41 weeks (11.65 per 10,000 ongoing pregnancies, 95% CI 6.95–18.09), compared to 39 weeks (12 per 10,000 live births, 95% CI 8.98–15.64 and 5.12 per 10,000 ongoing pregnancies, 95% CI 3.84–6.66, respectively).

Conclusion

In Korean women, delivery between 39 and 41 weeks minimizes fetal/infant mortality, in non-SGA pregnancies. In uncomplicated SGA pregnancies, delivery between 39 and 40 weeks can be considered to decrease risk of infant death and stillbirths.

Medically indicated late preterm delivery and its impact on perinatal morbidity and mortality: a retrospective population-based cohort study

Objective: In the last few decades, attention has been focused on morbidity and mortality associated with late preterm delivery (34-36 + 6/7 weeks), accounting for 60-70% of all preterm births. This study is aimed to determine (1) the prevalence of late preterm deliveries (spontaneous and medically indicated) in our population; and (2) the rate of neonatal morbidity and mortality as well as maternal complications associated with the different phenotypes of late preterm deliveries. Study design: This retrospective population-based cohort study, included 96,176 women who had 257,182 deliveries, occurred between 1988 and 2011, allocated into three groups: term (n = 242,286), spontaneous (n = 10,063), and medically indicated (n = 4833) late preterm deliveries. Results: (1) Medically indicated late preterm deliveries were associated with increased maternal morbidity, as well as neonatal morbidity and mortality, in comparison with other study groups (p < .01 for all comparisons); (2) medically indicated late preterm delivery was an independent risk factor for composite neonatal morbidity (low Apgar score at 5', seizures, asphyxia, acidosis) after adjustment for confounding factors (maternal age and ethnicity and neonatal gender) and stratification according to gestational age at delivery; and (3) the proportion of medically indicated late preterm deliveries affected the neonatal mortality rate. Below 35% of all late preterm deliveries, indicated late preterm birth were associated with a reduction in neonatal mortality; however, above this threshold medically indicated late preterm deliveries were associated with an increased risk for neonatal death. Conclusions: (1) Medically indicated late preterm deliveries were independently associated with adverse composite neonatal outcome; and (2) to benefit in term of neonatal outcome from the tool of medically indicated late preterm birth, their proportion should be kept below 35% of all late preterm deliveries, while exceeding this threshold increases the risk of neonatal mortality.

[Late preterm infants in Spain: Experience of the 34-36 Neonatal Group]

INTRODUCTION

Late preterm (LP) infants (34 -36 weeks of gestation) are the largest group of preterm infants and also the least studied so far. In order to improve their care and reduce the impact of their increased morbidity and mortality, it is essential to know the current situation in Spain.

POPULATION AND METHOD

Clinical-epidemiological variables of the LP population of 34 participating hospitals were prospectively collected from 1 April 2011 to 31 March 2016, and were then compared with the Minimum Perinatal Data Set for term births in the database.

RESULTS

Of the 9,121 LP studied, 21.7% of 34, 30.8% of 35, and 47.5% of 36 weeks of gestation. The mortality rate was 2.8%. More than one-quarter (27.7%) were multiple pregnancies. Maternal disease were identified in 47.1% and 41.4% were pathological gestation. Just under half (47.9%) were by Caesarean section and 18.8% were of unknown origin or unjustified. No known cause of prematurity was found in 29%, and 3.1% were recognized as unjustified?caesarean?. Just under half (47%) of the LP were breastfed, and 58.6% required admission to neonatology, with 15.2% to Neonatal Intensive Care Unit. Coded diagnoses were recorded in 46.2%, with the most frequent being jaundice, 43.5%, hypoglycaemia, 30%, and respiratory disorders with 28.7%.

CONCLUSIONS

The large sample of LP studied helps us to highlight the higher neonatal mortality and morbidity that this population suffers and the unavoidable relationship of its incidence with multiparity, maternal aging, and the still numerous inductions of labour and unjustified elective caesareans.

Trends in provider-initiated versus spontaneous preterm deliveries, 2004-2013

OBJECTIVE

The objectives of this study were as follows: (i) to estimate the proportion of preterm deliveries at a tertiary perinatal center that were provider-initiated versus spontaneous before and after a 2009 policy to reduce elective early-term deliveries, and (ii)to evaluate whether shifts in type of preterm delivery varied by race/ethnicity.

METHOD

We performed a retrospective cohort study of preterm deliveries over a 10-year period, 2004 to 2013, including detailed review of 929 of 5566 preterm deliveries, to designate each delivery as provider-initiated or spontaneous. We dichotomized the time period into early (2004 to 2009) and late (2010 to 2013). We used log-binomial regression to calculate adjusted risk ratios.

RESULT

Of the 46 981 deliveries, 5566 (11.8%) were preterm, with a significant reduction in the overall incidence of preterm delivery from 12.3 to 11.2% (P=0.0003). Among the 929 preterm deliveries analyzed, there was a reduction in the proportion of provider-initiated deliveries from 48.3 to 41.8% that was not statistically significant. The proportion of provider-initiated preterm deliveries among Black, but not White, women declined from 50.8 to 39.7% (adjusted relative risk: 0.66; 95% confidence interval (CI): 0.45 to 0.97). This coincided with a larger reduction in overall preterm deliveries among Black women (16.2 to 12.8%) vs White women (12.3 to 11.2%) (P interaction=0.038). By 2013, the incidence of preterm deliveries had decreased for both Black (12.1%) and White women (11.4%), and the difference was no longer statistically significant (P=0.7).

CONCLUSION

We found a reduction in preterm deliveries after a policy targeted at reducing elective early-term deliveries in 2009 that coincided with reductions in the proportion of provider-initiated preterm deliveries, especially among Black women.

Caesarean delivery and the risk of offspring overweight and obesity over the life course: a systematic review and bias-adjusted meta-analysis

A causal role of Caesarean delivery (CD) on developing overweight and obesity in the life course of offspring has been postulated. However, the true strength of this association is not clear and the potential for confounding has not been adequately addressed. A systematic review and meta-analysis were conducted to evaluate the strength of this association, this time using a bias-adjusted model in addition to conventional methods. Our search yielded 32 estimates from 14 publications (n = 261,000) for meta-analysis. The pooled analysis of seven estimates (n = 194,463) demonstrated a trend only towards a risk increase (RR = 1.15; 95% CI:0.94, 1.40) in overweight and obesity combined (ow+ob) due to CD in early childhood (0-5 years) and a similar trend was observed for mid-childhood and adolescence (5-18 years). In adulthood, a moderate increase in risk for ow+ob due to CD was observed (n = 30,200) (RR = 1.28; 95% CI 1.02, 1.34). Results for obesity and overweight separately were stronger for obesity and demonstrated a decreasing effect across the three life stages. Conventional methods of analysis suggested less uncertainty than we report and publication bias assessment was strongly suggestive of a bias in favour of positive studies. The current analysis therefore suggests that the small effects seen with CD in this and previous meta-analyses are probably a cumulative consequence of several biases we have outlined, including confounding effect and publication bias.

Genomics of preterm birth

The molecular mechanisms controlling human birth timing at term, or resulting in preterm birth, have been the focus of considerable investigation, but limited insights have been gained over the past 50 years. In part, these processes have remained elusive because of divergence in reproductive strategies and physiology shown by model organisms, making extrapolation to humans uncertain. Here, we summarize the evolution of progesterone signaling and variation in pregnancy maintenance and termination. We use this comparative physiology to support the hypothesis that selective pressure on genomic loci involved in the timing of parturition have shaped human birth timing, and that these loci can be identified with comparative genomic strategies. Previous limitations imposed by divergence of mechanisms provide an important new opportunity to elucidate fundamental pathways of parturition control through increasing availability of sequenced genomes and associated reproductive physiology characteristics across diverse organisms.