Placental blood flow and the risk of preterm delivery

Cesarean section at full dilatation in the first birth is not associated with an increased risk of subsequent miscarriage: A historical cohort study

INTRODUCTION

Cesarean section at full dilatation has been associated with an increased risk of subsequent preterm birth. We hypothesized that there may be an increased risk of miscarriage in pregnancies that follow cesarean section at full dilatation. This study aimed to determine if a first-term (≥37 weeks) cesarean section at full dilatation is associated with an increased risk of miscarriage in the next pregnancy.

MATERIAL AND METHODS

A historical cohort study was conducted using routinely collected hospital data within the Aberdeen Maternity and Neonatal Databank (AMND). The population included were women who had a first-term birth and who had a second birth recorded within the AMND. Logistic and multinomial regression was used to determine any association with miscarriage at any gestation and for early (<13 weeks gestation) and late (13-23 + 6 weeks gestation) miscarriage, with cesarean section at full dilatation defined as the exposure. Miscarriage in the second pregnancy (spontaneous loss of intrauterine pregnancy prior to 24 weeks gestation) was the primary outcome.

RESULTS

In total, 33 452 women were included. Women who had a first cesarean section at full dilatation were no more likely to have a miscarriage at any gestation than women with all other modes of first birth (including all vaginal births, planned CS, and the first stage of labor (<10 cm dilated CS)) [adjusted OR 0.84 (0.66-1.08); p = 0.18]. There was no association with early or late miscarriage after a CSfd, though the sample size for late miscarriage was small.

CONCLUSIONS

This is the first observational study to investigate the risk of miscarriage following first-term CSfd. We found no association between miscarriage at any gestation following a first-term CSfd compared to all other modes of first birth.

Operative delivery in the second stage of labor and preterm birth in a subsequent pregnancy: a systematic review and meta-analysis

OBJECTIVE

This study aimed to quantify the association between mode of operative delivery in the second stage of labor (cesarean delivery vs operative vaginal delivery) and spontaneous preterm birth in a subsequent pregnancy.

DATA SOURCES

MEDLINE, Embase, EmCare, CINAHL, the Cochrane Library, Web of Science: Core Collection, and Scopus were searched from database inception to April 1, 2023.

STUDY ELIGIBILITY CRITERIA

All retrospective cohort studies with participants who had a second-stage cesarean delivery (defined as intrapartum cesarean delivery at full cervical dilation) or operative vaginal delivery (including forceps- and/or vacuum-assisted delivery) and that reported the rate of preterm birth (either spontaneous or not specified) in subsequent pregnancy were included.

METHODS

Both a descriptive analysis and a meta-analysis were performed. A meta-analysis was performed for dichotomous data using the Mantel-Haenszel random-effects model and used the odds ratio as an effect measure with 95% confidence intervals. The risk of bias was assessed using Cochrane's 2022 Risk Of Bias In Non-randomized Studies of Exposure tool.

RESULTS

After screening 2671 articles from 7 databases, a total of 18 retrospective cohort studies encompassing 605,138 patients were included. The pooled rates of spontaneous preterm birth in a subsequent pregnancy were 6.9% (12 studies) after second-stage cesarean delivery and 2.6% (8 studies) after operative vaginal delivery. A total of 7 studies encompassing 75,460 patients compared the primary outcome of spontaneous preterm birth after second-stage cesarean delivery vs operative vaginal delivery in an index pregnancy with an odds ratio of 2.01 (95% confidence interval, 1.57-2.58) in favor of operative vaginal delivery. However, most studies did not include important confounding factors, did not address exposure misclassification because of failed operative vaginal delivery, and considered operative vaginal delivery as a homogeneous category with no distinction between forceps- and vacuum-assisted deliveries.

CONCLUSION

Although a synthesis of the existing literature suggests that the risk of spontaneous preterm birth is higher in those with a previous second-stage cesarean delivery than in those with operative vaginal delivery, the risk of bias in these studies is very high. Findings should be interpreted with caution.

Two-dimensional phase-contrast MRI reveals changes in uterine arterial blood flow in pregnant women administered tadalafil for fetal growth restriction

INTRODUCTION

We aimed to examine the effect of uterine arterial (UtA) blood flow changes after tadalafil treatment for fetal growth restriction (FGR) using two-dimensional (2D) phase-contrast magnetic resonance imaging (PC-MRI).

METHODS

We recruited 14 pregnant women with FGR aged 20-44 years, at ≥20 weeks' gestation, between May 2019 and July 2020. They underwent 2D PC-MRI for UtA blood flow measurement 3 days (interquartile range: 2-4) after diagnosis. This group (FGR group) was compared with 14 gestational age (GA)-matched healthy pregnant women (control group). Six patients in the FGR group received treatment with tadalafil administered at 20 mg twice daily after the first MRI until delivery. They underwent a second MRI a week later.

RESULTS

The median total UtA blood/body surface area was 420 mL/min/m2 (290-494) in the FGR group and 547 mL/min/m2 (433-681) in the control group (p = 0.01). Percent increase in blood flow were significantly different between the FGR cases treated with tadalafil and control at 15.8 % (14.3-21.3) and 4.2 % (3.6-8.7), respectively (p = 0.03).

DISCUSSION

UtA blood flow in pregnant women with FGR was significantly lower than that in healthy pregnant women. Tadalafil is expected to improve UtA blood flow, thereby improving placental function in pregnant patients with FGR.

Highlighting early detection of thyroid pathology and gestational diabetes effects on oxidative stress that provokes preterm delivery in thyroidology: Does that ring a bell?

OBJECTIVES

Ad fontes, the status of the thyroid gland, and metabolic disturbance lead to the alteration of oxygenation. In pregnancy, it is particularly crucial to possess all predictive parameters.

METHODS

This cross-sectional study was conducted at the Clinic of Gynecology and Obstetrics, Clinical Center of Serbia, Belgrade, Serbia, between 2017 and 2021 which study included a total of 99 women who had been admitted for preterm delivery and had undergone thyroid analysis, detected Hashimoto thyroiditis, and Oral Glucose Tolerance Test (OGTT) 40 days after delivery and had pathological Homeostatic Model Assessment for Insulin Response (HOMA IR) indices. In the group of urgent patients with preterm delivery, we looked after not only routine Doppler of the umbilical artery, but we measured specific ratios such as the Cerebroplacental ratio (CP).

RESULTS

The mean maternal age was 32.23 ± 5.96 years and the mean gestational age was detected as 35.40 ± 2.39 weeks. The delivery was completed vaginally in 77 women (78%) and surgically in 22 (22%). The Mean APGAR score was 8.44 ± 1.18, the mean birth weight was 2666.87 ± 622.17g and the cases undergoing cesarean section had significantly higher values of pulsatility index (1.85 ± 0.27 vs. 1.34 ± 0.31) and CP (1.22 ± 0.26 vs. 0.47 ± 0.17).

CONCLUSIONS

The introduction of Doppler sonography for blood flow assessment helps to form a complete clinical description of the patient, particularly in conditions where oxidative stress became provocative by the thyroid gland antibodies and gestational diabetes in Thyroidology.

Association between the first and second trimester cell free DNA fetal fraction and spontaneous preterm birth

OBJECTIVE

To evaluate whether the fetal fraction of cell-free DNA at the first and second trimesters is associated with spontaneous preterm birth.

METHODS

This was a retrospective cohort study with singleton pregnancies who underwent noninvasive prenatal testing. According to pregnancy outcome, eligible patients were divided into a delivery group ≥37 weeks of pregnancy (term group) and <37 weeks of pregnancy (spontaneous preterm group). Stepwise linear regression was used to identify maternal characteristics associated with the fetal fraction of cell-free DNA. Logistic regression analysis was performed to evaluate the association between the fetal fraction of cell-free DNA and spontaneous preterm birth, adjusted for confounding factors.

RESULTS

14,020 cases were included in the study, 13292 cases (94.81%) in the term group and 728 cases (5.19%) in the spontaneous preterm group. The cell-free fraction of fetal DNA was inversely correlated with maternal age and body mass index. Positively correlated with gestational age, fertility, and assisted reproductive technology. After adjusting for the covariates, logistic regression analysis revealed no statistically significant association between the fetal fraction of cell-free DNA and spontaneous preterm birth.

CONCLUSION

In our original study, we found no association between the fetal fraction on NIPT and subsequent spontaneous preterm birth.

Sequential disruptions to inflammatory and angiogenic pathways and risk of spontaneous preterm birth in Malawian women

Preterm birth is a leading cause of death in children under five years of age. We hypothesized that sequential disruptions to inflammatory and angiogenic pathways during pregnancy increase the risk of placental insufficiency and spontaneous preterm labor and delivery. We conducted a secondary analysis of inflammatory and angiogenic analytes measured in plasma samples collected across pregnancy from 1462 Malawian women. Women with concentrations of the inflammatory markers sTNFR2, CHI3L1, and IL18BP in the highest quartile before 24 weeks gestation and women with anti-angiogenic factors sEndoglin and sFlt-1/PlGF ratio in the highest quartile at 28-33 weeks gestation had an increased relative risk of preterm birth. Mediation analysis further supported a potential causal link between early inflammation, subsequent angiogenic dysregulation detrimental to placental vascular development, and earlier gestational age at delivery. Interventions designed to reduce the burden of preterm birth may need to be implemented before 24 weeks of gestation.

Impact of gestational hypertension and pre-eclampsia on preterm birth in China: a large prospective cohort study

OBJECTIVE

To investigate the impact of gestational hypertension and pre-eclampsia on preterm birth.

DESIGN

The data were collected from the China-US Collaborative Project for Neural Tube Defect Prevention; this was a large population-based cohort study.

SETTING AND PARTICIPANTS

We selected participants registered in two southern provinces, for whom we had exact information on gestational blood pressure and pregnancy outcomes, and who were not affected by chronic hypertension. In total, 200 103 participants were recruited from 1993 to 1995.

OUTCOME MEASURES

Preterm birth was defined as a singleton pregnancy and birth before 37 gestational weeks.

RESULTS

The incidences of gestational hypertension and pre-eclampsia were 5.47% and 5.44%, respectively, for women who gave birth at full term, and 5.63% and 7.33%, respectively, for those who gave birth preterm. After adjusting for potential confounders, the risk ratios (RRs) of preterm birth in women with gestational hypertension and pre-eclampsia were 1.04 (95% CI 0.98 to 1.11) and 1.39 (95% CI 1.25 to 1.55), respectively. The associations were stronger for early-onset (<28 weeks of gestation) gestational hypertension (adjusted RR=2.13, 95% CI 1.71 to 2.65) and pre-eclampsia (adjusted RR=8.47, 95% CI 5.59 to 12.80).

CONCLUSIONS

Pre-eclampsia was associated with a higher risk of preterm birth. The early-onset gestational hypertension and pre-eclampsia were associated with more severe risks than late-onset conditions.

Defective placentation syndromes and autism spectrum disorder in the offspring: population-based cohort and sibling-controlled studies

Defective placentation underlies diverse syndromic manifestations that could affect brain development including: (1) placental abruption, (2) term preeclampsia with a small-for-gestational age (SGA) infant, (3) preterm preeclampsia, and (4) spontaneous preterm birth. We investigated the relations between these defective placentation syndromes and the incidence of Autism Spectrum Disorder (ASD) in offspring. We conducted a population-based cohort study of 1,645,455 non-malformed singleton infants born in Sweden 2000-2016 who were followed for up to 17 years using national registers. We compared ASD rates for children prenatally exposed and unexposed to defective placentation syndromes with use of adjusted hazard ratios (HR) with 95% confidence intervals (CI) from Cox regression. We also conducted sibling-controlled analyses among 1,092,132 full siblings. The association of the syndromes with ASD independent of preterm birth was estimated in mediation analyses. There were 23,810 cases of ASD. In both general cohort and sibling analyses, adjusted HRs (95% CI) of ASD were increased in children of mothers with term preeclampsia combined with SGA [1.5 (1.3, 1.9) and 1.9 (1.1, 3.3), respectively], preterm preeclampsia < 34 weeks [1.8 (1.4, 2.2) and 4.2 (2.1, 8.5), respectively], and spontaneous very or extremely preterm birth (≤ 31 weeks) [2.6 (2.2, 3.0) and 2.4 (1.5, 3.8), respectively]. Placental abruption was associated with increased HR of ASD in general cohort analysis only. The association between preeclampsia and ASD was not fully explained by preterm birth. In conclusion, syndromes linked to defective placentation are associated with increased incidence of ASD in the offspring.

Evaluation of placental oxygenation in fetal growth restriction using blood oxygen level-dependent magnetic resonance imaging

INTRODUCTION

Abnormalities in placental function can lead to fetal growth restriction (FGR), but there is no consensus on their evaluation. Using blood oxygen level-dependent magnetic resonance imaging (BOLD MRI), we compared placental oxygenation between FGR cases and previously reported normal pregnancies.

METHODS

Eight singleton pregnant women (>32 weeks of gestation) diagnosed with fetal growth failure during pregnancy were recruited. BOLD MRI was consecutively performed under normoxia (21% O₂), hyperoxia (100% O₂), and normoxia for 4 min each. Each placental time-activity curve was evaluated to calculate the peak score (peakΔR2*) and the time from the start of maternal oxygen administration to the time of peakΔR2* (time to peakΔR2*). In six of the eight FGR cases, placental FGR-related pathological findings were evaluated after delivery.

RESULTS

The parameter peakΔR2* was significantly decreased in the FGR group (8 ± 3 vs 6 ± 1, p < 0.001), but there was no significant difference in time to peakΔR2* (458 ± 74 s vs 468 ± 57 s, p = 0.750). The findings in the six FGR cases assessed for placental pathologies included chorangiosis in two cases, avascular chorions in two cases, placental infarction in two cases, and syncytial knot formation in one case.

DISCUSSION

The peakΔR2* values were lower in the FGR group than in the normal pregnancy group. This suggests that oxygenation of the placenta is decreased in the FGR group compared to the normal group, and this may be related to FGR. Placental pathology also revealed findings possibly related to FGR, suggesting that low peakΔR2* values in the FGR group may reflect placental dysfunction.

Blood pressure trajectories during pregnancy and preterm delivery: A prospective cohort study in China

Women's blood pressure (BP) changes throughout pregnancy. The effect of BP trajectories on preterm delivery is not clear. The authors aim to evaluate the association between maternal BP trajectories during pregnancy and preterm delivery. The authors studied pregnant women included in the Born in Guangzhou Cohort Study in China between February 2012 and June 2016. Maternal BP was measured at antenatal visits between 13 and 40 gestational weeks, and gestational age of delivery data was collected. The authors used linear mixed models to capture the BP trajectories of women with term, and spontaneous and iatrogenic preterm delivery. BP trajectories of women with various gestational lengths (34, 35, 36, 37, 38, 39, 40 weeks) were compared. Of the 17 426 women included in the analysis, 618 (3.55%) had spontaneous preterm delivery; 158 (.91%) had iatrogenic preterm delivery; and 16 650 (95.55%) women delivered at term. The BP trajectories were all J‐shaped curves for different delivery types. Women with iatrogenic preterm delivery had the highest mean BP from 13 weeks till delivery, followed by those with spontaneous preterm delivery and term delivery (p < .001). Trajectory analysis stratified by maternal parity showed similar results for nulliparous and multiparous women. Excluding women with pre‐eclampsia and gestational hypertension (GH) significantly attenuated the aforementioned association. Also, women with shorter gestational length tend to have higher BP trajectories during pregnancy. In conclusion, Women with spontaneous preterm delivery have a higher BP from 13 weeks till delivery than women with term delivery, while women with iatrogenic preterm delivery have the highest BP.

Defective Placentation Syndromes and Intellectual Disability in the Offspring: Nationwide Cohort and Sibling-Controlled Studies

We investigated the relationships between syndromic manifestations of defective placentation and the incidence of intellectual disability (ID) in offspring by conducting a population-based cohort study of 1,581,200 nonmalformed, live singleton infants born in Sweden between 1998 and 2014. Exposures were: 1) placental abruption, 2) preterm preeclampsia (<34 weeks of gestation), 3) preeclampsia combined with infant being small for gestational age (SGA) at birth, and 4) spontaneous preterm birth. The outcome was an ID diagnosis after 3 years of age. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for each syndrome using Cox regression and robust variances. There were 9,451 children with ID (5.5 per 10,000 child-years). ID incidence rates increased with placental abruption (HR = 2.8, 95% CI: 2.3, 3.5), preterm preeclampsia (HR = 3.7, 95% CI: 2.9, 4.7), preeclampsia combined with SGA (HR = 3.3, 95% CI: 2.6, 4.1), and spontaneous preterm birth (for 32-36 and 22-31 weeks, respectively, HR = 1.6 (95% CI: 1.4, 1.8) and 5.2 (95% CI: 4.3, 6.2)). The same pattern of results was evident in sibling-controlled analyses among 1,043,158 full siblings. The strength of associations increased with ID severity. Preterm birth only partly explained the associations of placental abruption, preeclampsia, or SGA with ID. We conclude that defective placentation is related to increased incidence of ID in the offspring.

The Association Between Pregnancy-Induced Hypertension and Neonatal Cerebral Metabolism, Hemodynamics, and Brain Injury as Determined by Physiological Imaging

Pregnancy-induced hypertension (PIH) is common and may affect maternal and children’s healthcare. However, the neurobiological status of neonates born from mothers with PIH has yet to be elucidated. The present study employed physiological imaging to investigate the association between maternal PIH and a number of neonatal health parameters, including cerebral metabolism, hemodynamics, and pathophysiological vulnerabilities. Following the acquisition of ethical approval, we recruited 16 neonates with maternal PIH and 22 normal neonates (non-PIH) as controls. All neonates underwent magnetic resonance imaging (MRI) of the brain. Phase-contrast (PC) MRI and T2-relaxation-under-spin-tagging (TRUST) MRI were performed to determine global cerebral blood flow, oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO₂). These physiological parameters were then compared between PIH neonates and controls. Linear regression analysis was performed to investigate the associations between maternal PIH and each of the physiological parameters. Receiver operating characteristic curves (ROCs) were used to determine whether maternal systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) which could facilitate the diagnosis of neonatal brain injuries. PIH neonates showed significantly lower OEF (25.5 ± 8.8% vs. 32.6 ± 7.3%, P = 0.01) and CMRO₂ (29.7 ± 9.4 vs. 40.9 ± 15.0 μmol/100 g/min, P = 0.01) compared to the controls. Maternal blood pressure levels [PIH or non-PIH groups, each one standard deviation (SD) increase in SBP, DBP, and MAP, respectively] were negatively associated with OEF [regression coefficient (β) = −7.9, P = 0.007; β = −4.2, P = 0.004; β = −3.6, P = 0.02; β = −4.0, P = 0.008, respectively). Furthermore, each one SD increase in maternal DBP and MAP was negatively associated with CMRO₂ (β = −4.7, P = 0.03; β = −4.4, P = 0.04, respectively). The areas under the curves (AUCs) with 95% confidence intervals (CIs) for maternal SBP, DBP, and MAP were 0.90 (0.80–0.97), 0.85 (0.73–0.97), and 0.89 (0.76–0.99), respectively. The AUC values for maternal SBP, DBP, and MAP indicated good diagnostic ability for identifying neonatal brain injuries. The present study demonstrated that maternal PIH may be associated with a lower oxygen extraction and lower cerebral metabolism in neonates.

Translational insights into mechanisms and preventive strategies after renal injury in neonates

Adverse perinatal circumstances can cause acute kidney injury (AKI) and contribute to chronic kidney disease (CKD). Accumulating evidence indicate that a wide spectrum of perinatal conditions interferes with normal kidney development and ultimately leads to aberrant kidney structure and function later in life. The present review addresses the lack of mechanistic knowledge with regard to perinatal origins of CKD and provides a comprehensive overview of pre- and peri-natal insults, including genetic predisposition, suboptimal nutritional supply, obesity and maternal metabolic disorders as well as placental insufficiency leading to intrauterine growth restriction (IUGR), prematurity, infections, inflammatory processes, and the need for life-saving treatments (e.g. oxygen supplementation, mechanical ventilation, medications) in neonates. Finally, we discuss future preventive, therapeutic, and regenerative directions. In summary, this review highlights the perinatal vulnerability of the kidney and the early origins of increased susceptibility toward AKI and CKD during postnatal life. Promotion of kidney health and prevention of disease require the understanding of perinatal injury in order to optimize perinatal micro- and macro-environments and enable normal kidney development.

First trimester HtrA1 maternal plasma level and spontaneous preterm birth

OBJECTIVES

High temperature requirement A1 (HtrA1) is a serine protease detected in maternal plasma and in placental tissues during normal gestation and in various pathological conditions. The purpose of this study was to determine whether the maternal plasma concentration of HtrA1 in first trimester, alone or combined with other maternal factors, can be used to identify women at risk for spontaneous preterm birth (SPTB).

STUDY DESIGN

This is a cohort study on pregnant women at 12 weeks of gestation recruited between 2014 and 2016 and prospectively followed until delivery. One hundred and fifty-nine women were included in the study: 140 women delivered at term and 19 (11.9%) delivered spontaneously preterm. Plasma samples were assessed for HtrA1 by ELISA and data were compared between women which delivered at term with women which delivered preterm. A multiple logistic regression analysis was used to estimate the independent effect of women's characteristics on the probability of a SPTB.

RESULTS

SPTB was significantly associated with log HtrA1 values at 12 weeks of gestation, BMI before pregnancy and physical activity. In particular, the probability of a SPTB increases of 79% for every added unit of log HtrA1, while decreases of 18% for every added unit of BMI. In addition, physical activity was found as an important protective factor. The ROC curve showed that the model had a good accuracy in predicting SPTB, with an AUC equal to 0.83 (95%CI: 0.73-0.91).

CONCLUSIONS

Maternal plasma HtrA1 may be considered a marker of SPTB. In addition, our model indicates two factors that could be modified to reduce the risk of SPTB, i.e. BMI before pregnancy and maternal physical activity.

An observational claims data analysis on the risk of maternal chronic kidney disease after preterm delivery and preeclampsia

Women with complications of pregnancy such as preeclampsia and preterm birth are at risk for adverse long-term outcomes, including an increased future risk of chronic kidney disease (CKD) and end-stage kidney disease (ESKD). This observational cohort study aimed to examine the risk of CKD after preterm delivery and preeclampsia in a large obstetric cohort in Germany, taking into account preexisting comorbidities, potential confounders, and the severity of CKD. Statutory claims data of the AOK Baden-Wuerttemberg were used to identify women with singleton live births between 2010 and 2017. Women with preexisting conditions including CKD, ESKD, and kidney replacement therapy (KRT) were excluded. Preterm delivery (< 37 gestational weeks) was the main exposure of interest; preeclampsia was investigated as secondary exposure. The main outcome was a newly recorded diagnosis of CKD in the claims database. Data were analyzed using Cox proportional hazard regression models. The time-dependent occurrence of CKD was analyzed for four strata, i.e., births with (i) neither an exposure of preterm delivery nor an exposure of preeclampsia, (ii) no exposure of preterm delivery but exposure of at least one preeclampsia, (iii) an exposure of at least one preterm delivery but no exposure of preeclampsia, or (iv) joint exposure of preterm delivery and preeclampsia. Risk stratification also included different CKD stages. Adjustments were made for confounding factors, such as maternal age, diabetes, obesity, and dyslipidemia. The cohort consisted of 193,152 women with 257,481 singleton live births. Mean observation time was 5.44 years. In total, there were 16,948 preterm deliveries (6.58%) and 14,448 births with at least one prior diagnosis of preeclampsia (5.61%). With a mean age of 30.51 years, 1,821 women developed any form of CKD. Compared to women with no risk exposure, women with a history of at least one preterm delivery (HR = 1.789) and women with a history of at least one preeclampsia (HR = 1.784) had an increased risk for any subsequent CKD. The highest risk for CKD was found for women with a joint exposure of preterm delivery and preeclampsia (HR = 5.227). These effects were the same in magnitude only for the outcome of mild to moderate CKD, but strongly increased for the outcome of severe CKD (HR = 11.90). Preterm delivery and preeclampsia were identified as independent risk factors for all CKD stages. A joint exposure or preterm birth and preeclampsia was associated with an excessive maternal risk burden for CKD in the first decade after pregnancy. Since consequent follow-up policies have not been defined yet, these results will help guide long-term surveillance for early detection and prevention of kidney disease, especially for women affected by both conditions.

Spontaneous preterm birth: the underpinnings in the maternal and fetal genomes

Preterm birth (PTB) is a major cause of neonatal mortality and health complications in infants. Elucidation of its genetic underpinnings can lead to improved understanding of the biological mechanisms and boost the development of methods to predict PTB. Although recent genome-based studies of both mother and fetus have identified several genetic loci which might be implicated in PTB, these results suffer from a lack of consistency across multiple studies and populations. Moreover, results of functional validation of most of these findings are unavailable. Since medically indicated preterm deliveries have well-known heterogeneous causes, we have reviewed only those studies which investigated spontaneous preterm birth (sPTB) and have attempted to suggest probable biological mechanisms by which the implicated genetic factors might result in sPTB. We expect our review to provide a panoramic view of the genetics of sPTB.

Occupational exposure to whole body vibrations and birth outcomes - A nationwide cohort study of Swedish women

BACKGROUND

More women in reproductive ages are entering occupations where exposure to whole body vibrations (WBV) is common (e.g. in transportation and construction). Previous studies based on self-assessed exposure suggest increased risks of adverse birth outcomes, but it is unclear at what exposure levels and if the current exposure guidelines are appropriate during pregnancy.

OBJECTIVES

To investigate whether occupational WBV-exposure increases the risk of preterm birth, low birth weight, and/or small-for-gestational age, in a large, nationwide, prospective, cohort study.

DESIGN

The Fetal Air Pollution Exposure cohort (FAIR) was formed by merging data from multiple, national registers, and the present study includes singletons born 1994-2014 to working women in Sweden (n = 1,091,080 births). WBV-exposure was assessed quantitatively using a job-exposure matrix based on measurements, and calculated odds ratios were adjusted for potential confounders such as smoking and BMI, and other occupational exposures like noise, combustion particles, and physically and psychologically strenuous work. Data on absence from work (full-/part time, sick leave, parental leave, etc.) was also used.

RESULTS

Exposure to WBV during pregnancy, among women with low absence from work (n = 476,419), was associated with an increased risk of preterm birth, below the occupational exposure limit (1.15 m/s²). Compared to unexposed mothers, the OR was 1.38 (95% CI: 1.05, 1.83) for exposure ≥0.5 m/s², corresponding to an increase from 47/1000 cases to 65/1000 cases. No increased risk was found for small-for-gestational age.

CONCLUSIONS

Exposure to WBV was associated with an increased risk of preterm birth. The results suggest that the current permissible exposure and action levels for WBV-exposure do not adequately protect pregnant women with continuous exposure.

Placental Pathology, Cerebral Blood Flow, and Intraventricular Hemorrhage in Preterm Infants: Is There a Link?

BACKGROUND

There is growing evidence to support an association between placental inflammation and neurological sequelae of preterm infants. The goal of this study is to evaluate the relationship between placental pathology, post-natal Doppler cerebral resistive indices (RI's), and intraventricular hemorrhage (IVH) in premature infants.

METHODS

In a retrospective cohort study, preterm infants born between 23 0/7 and 32 6/7 weeks' gestation at Parkland Hospital were examined with placental pathology and serial ultrasound Doppler to evaluate for the primary outcome of IVH and death.

RESULTS

A total of 255 infants were included, and 166 (65%) had at least one significant placental pathology, most commonly chorioamnionitis. Infants with placental pathologies were significantly more likely to have mothers with clinical chorioamnionitis and to have lower gestational ages. There was no observed association between placental pathology and IVH or death. Secondary analysis demonstrated that resistive indices obtained from the first and second head ultrasounds were not different in infants with IVH.

CONCLUSION

In this study, we observed a high rate of placental pathologies but no alterations in cerebral indices on ultrasound, or differences in rates of IVH or death. Additional studies are necessary to delineate the relationship between placental pathology, white matter brain injury, and outcomes.

Increased incidence of hypertensive disorders of pregnancy in women with a history of spontaneous preterm birth: A longitudinal linked national cohort study

OBJECTIVE

Determine the risk of hypertensive disorders of pregnancy (HD) in women with a history of spontaneous preterm birth (SPTB).

STUDY DESIGN

Longitudinal linked national cohort study within the Dutch Perinatal Registry (1999-2009) on linked data among 349,291 women with a first and second singleton pregnancy in the Netherlands.

MAIN OUTCOME MEASURES

The incidence of HD, small for gestational age (SGA) and placental abruption in the second pregnancy.

RESULTS

Out of 349,291 women with a singleton first pregnancy, 19,991 (5.7%) had a SPTB. The incidence of HD in the second pregnancy was 8.1% in women with a previous SPTB, as compared to 5.6% in women with a previous term birth (aOR 1.49 (CI 1.41-1.57)). Also after excluding HD, SGA and/or placental abruption in the first pregnancy, women with a history of SPTB had a higher risk of HD in their second pregnancy compared to women with a previous term birth (4.6% versus 2.7%, aOR 1.77 (CI 1.64-191)). Similarly, the incidence of SGA and placental abruption was higher in the second pregnancy in women with a history of SPTB compared to term birth in the first pregnancy.

CONCLUSIONS

Women with a history of SPTB are at elevated risk of HD in the subsequent pregnancy. These results support shared pathophysiology between SPTB and HD.

Does low-dose aspirin initiated before 11 weeks' gestation reduce the rate of preeclampsia?

OBJECTIVE DATA

Preconception or early administration of low-dose aspirin might improve endometrial growth, placental vascularization, and organogenesis. Most studies have evaluated the potential benefit of preconception or early administration of low-dose aspirin in women with a history of recurrent pregnancy loss, women who have undergone in vitro fertilization, or women with thrombophilia or antiphospholipid syndrome. These women are at an increased risk of placenta-associated complications of pregnancy, including preeclampsia, preterm delivery, and fetal growth restriction.

STUDY OUTCOMES

We performed a systematic review and meta-analysis to evaluate the effect of low-dose aspirin initiated at <11 weeks' gestation on the risk of preeclampsia, gestational hypertension, or any hypertensive disorder of pregnancy. Secondary outcomes included preterm delivery at <37 weeks' gestation and fetal growth restriction.

STUDY APPRAISAL AND SYNTHESIS METHODS

We searched in MEDLINE via PubMed, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform from 1985 to November 2018. Entry criteria were randomized controlled trials evaluating the effect of aspirin administered at <11 weeks' gestation in preventing preeclampsia and/or hypertensive disorders in pregnancy or improving pregnancy outcomes in women with recurrent miscarriage as compared with placebo or no treatment and outcome data available or provided by authors for >85% of the study population. Relative risks with 95% confidence intervals were calculated for each study and pooled for global analysis as the effect measure. We assessed statistical heterogeneity in each meta-analysis using the χ² statistics, I², and Tau². Heterogeneity was considered substantial if an I² was greater than 50% and either the Tau² was greater than zero or there was a low P value (<0.10) in the χ² test for heterogeneity. Random-effects meta-analysis, weighted by the size of the studies, was performed to produce an overall summary on aspirin effect for each outcome. Sensitivity analysis by sequential omission of each individual study and by fixed-effects model was performed. Publication bias was not assessed because of the small number of included studies. Statistical analysis was performed using Stata release 14.0 (StataCorp).

RESULTS

The entry criteria were fulfilled by 8 randomized controlled trials on a combined total of 1426 participants. Low-dose aspirin initiated at <11 weeks' gestation was associated with a nonsignificant reduction in the risk of preeclampsia (relative risk, 0.52; 95% confidence interval, 0.23-1.17, P = .115), gestational hypertension (relative risk, 0.49; 95% confidence interval, 0.20-1.21; P = .121), and any hypertensive disorder of pregnancy (relative risk, 0.59; 95% confidence interval, 0.33-1.04, P = .067). Early administration of low-dose aspirin reduced the risk of preterm delivery (relative risk, 0.52; 95% confidence interval, 0.27-0.97, P = .040) but had no impact on the risk of fetal growth restriction (relative risk, 1.10; 95% confidence interval, 0.58-2.07, P = .775). Except for preterm delivery and any hypertensive disorder of pregnancy, sensitivity analysis demonstrated similar observations, therefore confirming the robustness of the analysis.

CONCLUSION

The administration of low-dose aspirin at <11 weeks' gestation in women at high risk does not decrease the risk of preeclampsia, gestational hypertension, any hypertensive disorder of pregnancy, and fetal growth restriction. However, it might reduce the risk of preterm delivery. Larger randomized controlled trials will be required to substantiate the findings.

Transplacental Transfer of Per- and Polyfluoroalkyl Substances (PFASs): Differences between Preterm and Full-Term Deliveries and Associations with Placental Transporter mRNA Expression

Previous studies demonstrated that per- and polyfluoroalkyl substances (PFASs) can cross the human placental barrier. However, their transplacental transfer efficiencies (TTEs) have not been investigated in preterm delivery, and the role of placental transport proteins has rarely been explored. Our study hypothesized that the TTEs of PFASs could differ between preterm and full-term deliveries, and some placental transporters could be involved in active maternofetal PFAS transfer. In the present study, the median TTEs of 16 individual PFAS chemicals or isomers were determined to be 0.23 to 1.72 in matched maternal-cord serum pairs with preterm delivery (N = 86), which were significantly lower than those (0.35 to 2.26) determined in full-term delivery (N = 187). Significant associations were determined between the TTEs of several PFASs and the mRNA expression levels of selected transporters located on the brush border membrane. The association patterns also significantly differed between preterm and full-term deliveries and exhibited a chemical-specific manner. For example, the expression of MRP2 exhibited significantly positive associations with the TTEs of linear and branched perfluorooctanesulfonic acid (PFOS) isomers in full-term delivery, but negative, nonsignificant associations were observed in preterm delivery. This is the first study to compare the transplacental transfer of PFASs between preterm and full-term deliveries and indicate that some placental transport proteins could be involved in active transmission. The mechanisms underlying the cross-placental transfer of PFASs require further investigations to better elucidate their risks to fetal health and birth outcomes.

Anesthetic Management of a Voluminous Left Atrial Myxoma Resection in a 19 Weeks Pregnant with Atypical Clinical Presentation

We report the case of a semi-urgent cardiac surgery, in a 19 gestation age pregnant. Despite the fact that the patient was asymptomatic, except for some palpitations, a large left auricle (LA) myxoma was fortuitously diagnosed with transthoracic echocardiography (TEE). Considering the important embolic risk, the tumor was successfully removed during cardiac surgery under cardiopulmonary bypass (CPB). Fetal bradycardia following defibrillation under stable maternal and CPB conditions was successfully managed. The postoperative period and remainder of the pregnancy was smooth and the delivery uneventful.

Maternal vascular malperfusion in spontaneous preterm birth placentas related to clinical outcome of subsequent pregnancy

INTRODUCTION

Spontaneous preterm birth (SPTB) has several causes and its pathophysiology remains unclear. In a significant proportion of SPTB, placental histology shows signs of maternal vascular malperfusion (MVM); commonly associated with hypertensive disorders of pregnancy (HD), fetal growth restriction (FGR) and placental abruption, together referred to as clinical ischemic placental diseases (IPD). We hypothesized that women with SPTB and placental MVM are at elevated risk for IPD in a subsequent pregnancy.

METHODS

We included women with SPTB in our cohort and followed the subsequent ongoing pregnancy (n = 110). Histological placental characteristics in the index were reported according to new international guidelines, and related to the clinical outcome of the subsequent pregnancy.

RESULTS

In the SPTB placentas, we observed MVM in 61.8% (n = 68). In the subsequent pregnancies in 19.1% (n = 21) at least one clinical sign of IPD was present (HD (12.7%), FGR (5.5%) or placental abruption (0.9%)). There was no significant difference in the prevalence of clinical IPD or recurrence of SPTB in the subsequent pregnancy between women with and without placental MVM in the index pregnancy, although our study was not powered to detect small differences.

DISCUSSION

Women with a history of SPTB have an elevated risk of IPD in the subsequent pregnancy. MVM is present in a large proportion of SPTB placentas. The presence of placental MVM in the index pregnancy does not predict clinical IPD or recurrent SPTB in a subsequent pregnancy.

Cardiovascular and Metabolic Risk in Women in the First Year Postpartum: Allostatic Load as a Function of Race, Ethnicity, and Poverty Status

OBJECTIVE

Allostatic load (AL) represents multisystem physiological "wear-and-tear" reflecting emerging chronic disease risk. We assessed AL during the first year postpartum in a diverse community sample with known health disparities.

STUDY DESIGN

The Eunice Kennedy Shriver National Institute for Child Health and Human Development Community Child Health Network enrolled 2,448 predominantly low-income African-American, Latina, and White women immediately after delivery of liveborn infants at ≥20 weeks' gestation, following them over time with interviews, clinical measures, and biomarkers. AL at 6 and 12 months postpartum was measured by body mass index, waist:hip ratio, blood pressure, pulse, hemoglobin A1c, high-sensitive C-reactive protein, total cholesterol and high-density lipoprotein, and diurnal cortisol slope.

RESULTS

Adverse AL health-risk profiles were significantly more prevalent among African-American women compared with non-Hispanic Whites, with Latinas intermediate. Breastfeeding was protective, particularly for White women. Complications of pregnancy were associated with higher AL, and disparities persisted or worsened through the first year postpartum.

CONCLUSION

Adverse AL profiles occurred in a substantial proportion of postpartum women, and disparities did not improve from birth to 1 year. Breastfeeding was protective for the mother.

Low-dose aspirin is associated with reduced spontaneous preterm birth in nulliparous women

BACKGROUND

Preterm birth is one of the leading causes of perinatal morbidity and mortality. Clinical data suggest that low-dose aspirin may decrease the rate of overall preterm birth, but investigators have speculated that this is likely due to a decrease in medically indicated preterm birth through its effect on the incidence of preeclampsia and other placental disease. We hypothesized that low-dose aspirin may also have an impact on the mechanism of spontaneous preterm labor.

OBJECTIVE

Our objective was to determine whether low-dose aspirin reduces the rate of spontaneous preterm birth in nulliparous women without medical comorbidities.

STUDY DESIGN

This is a secondary analysis of a randomized, placebo-controlled trial of low-dose aspirin for the prevention of preeclampsia in healthy, low-risk, nulliparous women. Low-risk women were defined by the absence of hypertension, renal disease, diabetes, other endocrine disorders, seizures, heart disease, or collagen vascular disease. Our study was limited to singleton, nonanomalous gestations. Women were eligible if they had prior pregnancy terminations but not prior spontaneous pregnancy loss <20 weeks. Current pregnancies that resulted in a loss or termination <20 weeks or antepartum stillbirth or had missing follow-up data were excluded. The treatment intervention was 60 mg of aspirin, initiated at 13-25 weeks' gestation or matching placebo. The primary outcome was spontaneous preterm birth <34 weeks' gestation. Secondary outcomes included spontaneous preterm birth <37 weeks and overall preterm birth <37 and <34 weeks. Baseline demographics and primary and secondary outcomes were compared between treatment groups. A logistic regression model was used to adjust for confounders related to spontaneous preterm birth.

RESULTS

Of 2543 included women, 1262 (49.6%) received low-dose aspirin and 1281 (50.4%) placebo. Baseline characteristics were similar between groups, except for marital status. The rate of spontaneous preterm birth <34 weeks was 1.03% (n = 13) and 2.34% (n = 30) in the low-dose aspirin and placebo group, respectively (odds ratio, 0.43, 95% confidence interval, 0.26-0.84). Additionally, the rate of spontaneous preterm birth <37 weeks was 6.58% (n = 83) in the low-dose aspirin group and 7.03% (n = 90) in the placebo group (odds ratio, 0.97, 95% confidence interval, 0.71-1.33), and the rate of overall preterm birth <37 weeks was 7.84% (n = 99) in the low-dose aspirin group and 8.2% (n = 105) in the placebo group (odds ratio, 0.97, 95% confidence interval, 0.72-1.31). After adjustment for variables that were clinically relevant or statistically significant, including body mass index, race, tobacco use, marital status, and education level, there was a significant reduction in spontaneous preterm birth <34 weeks in the low-dose aspirin group (adjusted odds ratio, 0.46, 95% confidence interval, 0.23-0.89). The rates of overall preterm birth <34 and <37 weeks and spontaneous preterm birth <37 weeks were similar in women who received low-dose aspirin compared with placebo.

CONCLUSION

Low-dose aspirin is associated with a substantial decrease in spontaneous preterm birth <34 weeks in healthy nulliparous women without comorbidities. These findings suggest a new therapeutic option for preterm birth prevention that requires further study.

Prenatal air pollution exposure, smoking, and uterine vascular resistance

BACKGROUND

Prenatal exposure to air pollution and smoking increases the risk of pregnancy complications and adverse birth outcomes, but pathophysiologic mechanisms are still debated. Few studies to date have examined the influence of air pollution on uterine vascular resistance and no studies have examined the independent impact of these exposures. We aimed to assess the impact of prenatal exposure to traffic-related air pollution and smoking on uterine vascular resistance.

METHODS

Our study included 566 pregnant women recruited between 1993 and 1996 in Los Angeles who completed visits at three gestational ages. Information on smoking was collected and uterine vascular resistance was measured at each visit by Doppler ultrasound. We calculated three resistance indices: the resistance index (RI), the pulsatility index (PI), and the systolic/diastolic (S/D) ratio. We estimated exposure to NO2 at the home address of the mother using a land use regression (LUR) model and to NOx using CALINE4 air dispersion modeling. We used generalized linear mixed models to estimate the effects of air pollution and smoking on uterine vascular resistance indices.

RESULTS

LUR-derived NO2 and CALINE4-derived NOx exposure increased the risk of high uterine artery resistance in late pregnancy. Smoking during pregnancy also increased the risk of higher uterine resistance and contributed to bilateral notching in mid-pregnancy.

CONCLUSION

Our results suggest that uterine vascular resistance is a mechanism underlying the association between smoking and air pollution, and adverse birth outcomes.

Maternal exercise during pregnancy reduces the risk of preterm birth through the mediating role of placenta

OBJECTIVE

The extent of research on maternal exercise during pregnancy and the risk of preterm birth (PTB) have grown substantially, but conclusions still remained controversial. Thus, this study aims to examine the relationship of maternal exercise during pregnancy and PTB and explore whether placenta mediates their relationship.

STUDY DESIGN

We investigated 849 pregnant women delivering PTB newborns (cases) and 1306 delivering full-term appropriate for gestational age newborns (controls) in this case-control study. Information concerning maternal exercise during pregnancy, sociodemographics and obstetric characteristics were collected at Women and Children's Hospitals of Shenzhen and Foshan in Guangdong, China. A series of logistic and linear regressions were used to examine the relationships of maternal exercise during pregnancy, placenta, and PTB.

RESULTS

After adjusting for the potential confounders, maternal exercise frequency and duration during pregnancy were negatively associated with PTB. Moreover, compared with mother taking no exercise during pregnancy, those taking exercise lowered the risk of PTB except those taking low/medium frequency and short duration exercise, and their adjusted ORs ranged from 0.43 to 0.65. Furthermore, mediation analysis illustrated that placental weight partially mediated 65.20% of the effects of maternal exercise frequency on PTB, as well as 41.98% of the association between maternal exercise duration and PTB.

CONCLUSIONS

Maternal exercise during pregnancy is beneficial for lowering the risk of PTB, especially when taking appropriate and enough exercise. Placenta weight may partially mediate the association between maternal exercise during pregnancy and PTB.

Low dose aspirin in the prevention of recurrent spontaneous preterm labour - the APRIL study: a multicenter randomized placebo controlled trial

BACKGROUND

Preterm birth (birth before 37 weeks of gestation) is a major problem in obstetrics and affects an estimated 15 million pregnancies worldwide annually. A history of previous preterm birth is the strongest risk factor for preterm birth, and recurrent spontaneous preterm birth affects more than 2.5 million pregnancies each year. A recent meta-analysis showed possible benefits of the use of low dose aspirin in the prevention of recurrent spontaneous preterm birth. We will assess the (cost-)effectiveness of low dose aspirin in comparison with placebo in the prevention of recurrent spontaneous preterm birth in a randomized clinical trial.

METHODS/DESIGN

Women with a singleton pregnancy and a history of spontaneous preterm birth in a singleton pregnancy (22-37 weeks of gestation) will be asked to participate in a multicenter, randomized, double blinded, placebo controlled trial. Women will be randomized to low dose aspirin (80 mg once daily) or placebo, initiated from 8 to 16 weeks up to maximal 36 weeks of gestation. The primary outcome measure will be preterm birth, defined as birth at a gestational age (GA) < 37 weeks. Secondary outcomes will be a composite of adverse neonatal outcome and maternal outcomes, including subgroups of prematurity, as well as intrauterine growth restriction (IUGR) and costs from a healthcare perspective. Preterm birth will be analyzed as a group, as well as separately for spontaneous or indicated onset. Analysis will be performed by intention to treat. In total, 406 pregnant women have to be randomized to show a reduction of 35% in preterm birth from 36 to 23%. If aspirin is effective in preventing preterm birth, we expect that there will be cost savings, because of the low costs of aspirin. To evaluate this, a cost-effectiveness analysis will be performed comparing preventive treatment with aspirin with placebo.

DISCUSSION

This trial will provide evidence as to whether or not low dose aspirin is (cost-) effective in reducing recurrence of spontaneous preterm birth.

TRIAL REGISTRATION

Clinical trial registration number of the Dutch Trial Register: NTR 5675 . EudraCT-registration number: 2015-003220-31.

Antiplatelet Agents and the Prevention of Spontaneous Preterm Birth: A Systematic Review and Meta-analysis

OBJECTIVE

Spontaneous preterm birth is an important cause of neonatal mortality and morbidity. An increasing body of evidence suggests that uteroplacental ischemia plays an important role in the etiology of spontaneous preterm birth. We aimed to study whether antiplatelet agents reduce the risk of spontaneous preterm birth.

DATA SOURCES

We included data from an individual participant data meta-analysis of studies that had evaluated the effect of antiplatelet agents to reduce preeclampsia (Perinatal Antiplatelet Review of International Studies Individual Participant Data).

METHODS OF STUDY SELECTION

The meta-analysis included 31 studies that randomized women to low-dose aspirin-dipyridamole or placebo-no treatment as a primary preventive strategy for preeclampsia. For the current study we analyzed data from 17 trials (28,797 women) that supplied data on type of delivery (spontaneous compared with indicated birth).

TABULATION, INTEGRATION, AND RESULTS

Primary endpoints were spontaneous preterm birth at less than 37 weeks, less than 34 weeks, and less than 28 weeks of gestation. We analyzed outcomes for each trial separately using χ statistics and combined in an individual participant data meta-analysis using a binary logistic regression model. Women assigned to antiplatelet treatment compared with placebo or no treatment had a lower risk of spontaneous preterm birth at less than 37 weeks (relative risk [RR] 0.93, 95% confidence interval [CI] 0.86-0.996) and less than 34 weeks of gestation (RR 0.86, 95% CI 0.76-0.99). The RR of having a spontaneous preterm birth at less than 37 weeks of gestation was 0.83 (95% CI 0.73-0.95) for women who have had a previous pregnancy and 0.98 (95% CI 0.89-1.09) for women in their first pregnancy. The treatment effect was stable in all other prespecified subgroups.

CONCLUSION

Antiplatelet agents reduce spontaneous preterm birth in pregnant women at risk for preeclampsia.

Preterm Delivery as a Unique Pathophysiologic State Characterized by Maternal Soluble FMS-Like Tyrosine Kinase 1 and Uterine Artery Resistance During Pregnancy: A Longitudinal Cohort Study

BACKGROUND

Preterm delivery (PTD) may be characterized by altered interrelationships among angiogenic factors and measures of placental function. We analyzed the longitudinal relationship between maternal serum concentrations of soluble fms-like tyrosine kinase 1 (sFlt1), an important antiangiogenic factor, and uterine artery resistance in pregnancies resulting in preterm and term deliveries.

METHODS

Data were collected in a longitudinal cohort study involving 278 women monitored at 6 to 10, 10 to 14, 16 to 20, 22 to 26, and 32 to 36 weeks of gestation. Concentrations of maternal serum sFlt1 were determined using solid-phase enzyme-linked immunosorbent assay, and uterine artery resistance indices (RI) were measured by Doppler velocimetry at each interval. Preterm delivery was defined as birth before 37-weeks completed gestation. Data analyses used multivariable repeated measures regression models.

RESULTS

Uterine artery RI decreased across gestation. As pregnancy progressed, RI trajectories diverged for term and preterm deliveries; the mean RI was significantly higher in third trimester for pregnancies resulting in PTD ( P = .08). sFlt1 was stable through 21 3/7 weeks of gestation and then increased rapidly; women who delivered preterm had significantly higher sFlt1 levels in the third trimester ( P = .04). The relationship between uterine artery RI and sFlt1 from the prior visit was significantly different between the groups ( P < .0001). For term deliveries, higher sFlt1 concentrations were associated with a smaller RI at the subsequent visit (β = -.08, 95% confidence interval [CI]: -0.14 to -0.02). For PTD, higher sFlt1 concentrations were associated with a larger uterine artery RI (β = .14, 95% CI: 0.06 to 0.22).

CONCLUSION

PTD is characterized by altered relationships between angiogenic factors and placental vascular blood flow starting in early pregnancy.

Cell-free DNA fetal fraction and preterm birth

BACKGROUND

Cell-free deoxyribonucleic acid (DNA) is increasingly being used to screen for fetal aneuploidy. The majority of fetal cell-free DNA in the maternal blood results from release from the syncytiotrophoblast as a result of cellular apoptosis and necrosis. Elevated levels of fetal cell-free DNA may be indicative of underlying placental dysfunction, which has been associated with preterm birth. Preliminary studies have demonstrated that fetal cell-free DNA is increased in pregnancies complicated by spontaneous preterm birth. There are limited data on the association between fetal cell-free DNA levels and fetal fraction and preterm birth in asymptomatic women in the first and second trimesters. Preliminary studies have failed to find an association between first-trimester cell-free DNA levels and preterm birth, whereas there is conflicting evidence as to whether elevated second-trimester cell-free DNA is associated with a subsequent spontaneous preterm birth clinical event.

OBJECTIVE

The objective of the study was to evaluate the association between first- and second-trimester cell-free DNA fetal fraction and preterm birth.

STUDY DESIGN

This was a retrospective cohort study of women with singleton pregnancies at increased risk for aneuploidy who had cell-free DNA testing at 10-20 weeks' gestation between October 2011 and May 2014. The cohort was subdivided by gestational age at the time of cell-free DNA testing (10-14 weeks or 14.1-20 weeks). The primary outcome was preterm birth less than 37 weeks' gestation, and the secondary outcomes were preterm birth at less than 34 weeks' gestation and spontaneous preterm birth at less than 37 and 34 weeks' gestation.

RESULTS

Among 1349 pregnancies meeting inclusion criteria 119 (8.8 %) had a preterm birth prior to 37 weeks with 49 cases (3.6 %) delivering prior to 34 weeks. Whereas there was no significant association between fetal fraction and the preterm birth outcomes for those who underwent cell-free DNA testing at 10-14 weeks' gestation, there were significant associations among those screened at 14.1-20.0 weeks' gestation. Fetal fraction greater than or equal to the 95th percentile at 14.1-20.0 weeks' gestation was associated with an increased risk for preterm birth less than 37 and 34 weeks' gestation (adjusted odds ratio, 4.59; 95% confidence interval, 1.39-15.2; adjusted odds ratio, 22.0; 95% confidence interval, 5.02-96.9).

CONCLUSION

Elevated fetal fraction levels at 14.1-20.0 weeks' gestation were significantly associated with an increased incidence of preterm birth. Our findings warrant future exploration including validation in a larger, general population and investigation of the potential mechanisms that may be responsible for the initiation of preterm labor associated with increased fetal cell-free DNA.

Polyunsaturated Fatty Acid (PUFA) Status in Pregnant Women: Associations with Sleep Quality, Inflammation, and Length of Gestation

Mechanistic pathways linking maternal polyunsaturated fatty acid (PUFA) status with gestational length are poorly delineated. This study examined whether inflammation and sleep quality serve as mediators, focusing on the antiinflammatory ω-3 docosahexaenoic acid (DHA; 22:6n3) and proinflammatory ω-6 arachidonic acid (AA; 20:4n6). Pregnant women (n = 135) provided a blood sample and completed the Pittsburgh Sleep Quality Index (PSQI) at 20–27 weeks gestation. Red blood cell (RBC) fatty acid levels were determined by gas chromatography and serum inflammatory markers [interleukin (IL)-6, IL-8, tumor necrosis factor-α, IL-1β, and C-reactive protein] by electrochemiluminescence using high sensitivity kits. Both higher serum IL-8 (95% CI = 0.10,3.84) and poor sleep (95% CI = 0.03,0.28) served as significant mediators linking lower DHA:AA ratios with shorter gestation. Further, a serial mediation model moving from the DHA:AA ratio → sleep → IL-8 → length of gestation was statistically significant (95% CI = 0.02, 0.79). These relationships remained after adjusting for depressive symptoms, age, BMI, income, race, and smoking. No interactions with race were observed in relation to length of gestation as a continuous variable. However, a significant interaction between race and the DHA:AA ratio in predicting preterm birth was observed (p = 0.049); among African Americans only, odds of preterm birth decreased as DHA:AA increased (p = 0.048). These data support a role for both inflammatory pathways and sleep quality in linking less optimal RBC PUFA status with shorter gestation in African American and European American women and suggest that African-Americans have greater risk for preterm birth in the context of a low DHA:AA ratio.

Poor Sleep Quality and Associated Inflammation Predict Preterm Birth: Heightened Risk among African Americans

STUDY OBJECTIVES

Poor sleep promotes inflammation. In turn, inflammation is a causal mechanism in term as well as preterm parturition. In the United States, a persistent racial disparity in preterm birth exists, with African Americans showing ∼1.5 times greater risk. This study examined associations among sleep quality, serum proinflammatory cytokines, and length of gestation in a racially diverse sample of 138 pregnant women.

DESIGN

Observational.

MEASUREMENTS

Women completed the Pittsburgh Sleep Quality Index (PSQI) and other psychosocial and behavioral measures during midpregnancy. Serum levels of interleukin (IL)-6, IL-8, IL-1β, and tumor necrosis factor (TNF)-α were determined by high-sensitivity assays. Birth outcomes were determined via medical record review.

RESULTS

Among African American women (n = 79), shorter gestation was predicted by poorer overall sleep (rs = -0.35, P = 0.002) as well the following PSQI subscales: subjective sleep quality (rs = -0.34, P = 0.002), sleep latency (rs = -0.27, P = 0.02), and sleep efficiency (rs = -0.27, P = 0.02). African American women with poor sleep quality (PSQI > 5) had 10.2 times the odds of preterm birth compared to those with good sleep quality. In contrast, among European American women (n = 53), gestational length was not significantly predicted by sleep quality (Ps > 0.12). Bootstrapping analyses showed that, among African Americans, IL-8 significantly mediated the association between sleep quality and length of gestation (indirect effect estimate -0.029; 95% confidence interval -0.06, -0.002).

CONCLUSIONS

The data provide novel evidence that African American women exhibit greater inflammation in response to sleep disturbance than European American women and these effects correspond with length of gestation. Racial differences in susceptibility to sleep induced immune dysregulation may contribute to marked racial disparities in preterm birth.

Maternal anxiety during pregnancy and adverse birth outcomes: a systematic review and meta-analysis of prospective cohort studies

BACKGROUND

Previous studies concerning the association between maternal anxiety during pregnancy and adverse birth outcomes have provided controversial findings.

METHODS

In this systematic review, a meta-analysis was utilized to investigate the association between maternal anxiety and preterm birth (PTB) and/or low birth weight (LBW). Literature was searched until June 2013. Only prospective cohort studies that reported data on maternal anxiety during pregnancy with PTB and/or LBW were included. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated using fixed or random effects models depending on the size of heterogeneity.

RESULTS

Twelve studies totaling 17,304 pregnant women reported PTB data; and six studies totaling 4948 pregnant women reported LBW data. Maternal anxiety during pregnancy was associated with significant increased risk of PTB (pooled RR=1.50, 95% CI=1.33-1.70) and LBW (pooled RR=1.76, 95% CI=1.32-2.33).

LIMITATIONS

Potential moderators could not be adequately considered due to insufficient information. In addition, the effects of different types of anxiety disorder on the risk of these adverse birth outcomes could not be investigated.

CONCLUSIONS

The results suggested that maternal anxiety during pregnancy was positively related to an increased risk of PTB and LBW. Healthcare providers should give close attention to anxiety in pregnant women and provide appropriate mental health support in order to improve outcomes for both mothers and infants.

Third-trimester abnormal uterine artery Doppler findings are associated with adverse pregnancy outcomes

OBJECTIVES

To evaluate the association between third-trimester abnormal uterine artery Doppler findings and pregnancy outcomes.

METHODS

A prospective study was designed, including 198 consecutive singleton pregnancies between 27 and 41 weeks' gestation. In the study population, 144 had normal uterine artery Doppler waveforms, 37 had unilateral pathologic waveforms, and 17 had bilateral pathologic waveforms. Eighty patients had intrauterine growth restriction (IUGR), preeclampsia toxemia, or both, and 118 had no complications and served as a control group. The uterine artery Doppler waveform was considered abnormal when a notch or pulsatility index above the 90th percentile was noted.

RESULTS

In patients with bilateral pathologic uterine artery Doppler waveforms, the rates of cesarean delivery, small-for-gestational-age (SGA) neonates, preterm delivery, and low Apgar scores were increased compared to patients with normal or pathologic unilateral waveforms (P = .009; P > .001; P = .007; P > .001, respectively). The incidence rates for SGA neonates, cesarean delivery, and preterm delivery were significantly higher among patients without IUGR or preeclampsia toxemia when associated with pathologic bilateral waveforms in comparison to normal waveforms (P = .01 for all). A bilateral pathologic waveform was found to be an independent risk factor for cesarean delivery and SGA neonates. The incidence rates for SGA neonates and preterm delivery were significantly higher among patients with IUGR and/or preeclampsia toxemia when associated with bilateral abnormalities in comparison to normal waveforms (P = .01 for both).

CONCLUSIONS

Third-trimester abnormal uterine artery Doppler findings are associated with worse perinatal outcomes among patients both with and without pregnancy complications.

Association of early-preterm birth with abnormal levels of routinely collected first- and second-trimester biomarkers

OBJECTIVE

The purpose of this study was to examine the relationship between typically measured prenatal screening biomarkers and early-preterm birth in euploid pregnancies.

STUDY DESIGN

The study included 345 early-preterm cases (<30 weeks of gestation) and 1725 control subjects who were drawn from a population-based sample of California pregnancies who had both first- and second-trimester screening results. Logistic regression analyses were used to compare patterns of biomarkers in cases and control subjects and to develop predictive models. Replicability of the biomarker early-preterm relationships that was revealed by the models was evaluated by examination of the frequency and associated adjusted relative risks (RRs) for early-preterm birth and for preterm birth in general (<37 weeks of gestation) in pregnancies with identified abnormal markers compared with pregnancies without these markers in a subsequent independent California cohort of screened pregnancies (n = 76,588).

RESULTS

The final model for early-preterm birth included first-trimester pregnancy-associated plasma protein A in the ≤5th percentile, second-trimester alpha-fetoprotein in the ≥95th percentile, and second-trimester inhibin in the ≥95th percentile (odds ratios, 2.3-3.6). In general, pregnancies in the subsequent cohort with a biomarker pattern that were found to be associated with early-preterm delivery in the first sample were at an increased risk for early-preterm birth and preterm birth in general (<37 weeks of gestation; adjusted RR, 1.6-27.4). Pregnancies with ≥2 biomarker abnormalities were at particularly increased risk (adjusted RR, 3.6-27.4).

CONCLUSION

When considered across cohorts and in combination, abnormalities in routinely collected biomarkers reveal predictable risks for early-preterm birth.

Placental villous hypermaturation is associated with idiopathic preterm birth

OBJECTIVE

Pregnancy complications such as intra-amniotic infection, preeclampsia, and fetal intrauterine growth restriction (IUGR) account for most cases of preterm birth (PTB), but many spontaneous PTB cases do not have a clear etiology. We hypothesize that placental insufficiency may be a potential cause of idiopathic PTB.

METHODS

Secondary analysis of 82 placental samples from women with PTB obtained from a multicenter trial of repeat versus single antenatal corticosteroids. Samples were centrally reviewed by a single placental pathologist masked to clinical outcomes. The histopathologic criterion for infection was the presence of acute chorioamnionitis defined as neutrophils marginating into the chorionic plate. Placental villous hypermaturation (PVH) was defined as a predominance of terminal villi (similar to term placenta) with extensive syncytial knotting. Idiopathic PTB comprised a group without another known etiology such as preeclampsia, IUGR or infection.

RESULTS

Acute chorioamnionitis was observed in 33/82 (40%) cases. Other known causes of PTB were reported in 18/82 (22%). The remaining 31/82 (38%) were idiopathic. The frequency of PVH in idiopathic PTB (26/31 = 84%) was similar to cases with IUGR or preeclampsia (16/18 = 89%), but significantly more common than PVH in the group with acute chorioamnionitis (10/33 = 30%) (p < 0.001).

CONCLUSIONS

PVH, which is a histologic marker of relative placental insufficiency, is a common finding in idiopathic PTB.

First trimester serum analytes, maternal characteristics and ultrasound markers to predict pregnancies at risk for preterm birth

INTRODUCTION

Markers of placental dysfunction are used for risk prediction of adverse obstetric outcomes including preeclampsia and growth restriction. Although medically indicated preterm birth is often distinguished from spontaneous preterm birth, we hypothesize that similar placental dysfunction may underlay all preterm birth. We aimed to investigate whether first trimester placental protein 13 (PP-13), pregnancy associated plasma protein A (PAPP-A) and uterine artery pulsatility index, with maternal characteristics could be used to predict all preterm birth.

METHODS

Prospective cohort study of singleton gestations between 11 and 14 weeks who underwent serum measurement of PP-13, PAPP-A, and measurement of uterine artery Doppler pulsatility index. Primary outcomes were preterm birth (PTB) at less than 37 and 33 weeks. Analysis performed both including and excluding preeclampsia to assess the utility of the predictors for all types of preterm birth. Predictive models assembled using logistic regression with each predictor alone and in combination, along with maternal characteristics. Predictive utility of models was assessed using receiver operating curve (ROC) analysis and sensitivities for fixed false positive values.

RESULTS

Of 471 women, PTB occurred in 12.5% and early PTB (<33 weeks) occurred in 4.7%. PP-13 was decreased in PTB <37 weeks. PAPP-A was decreased in a dose-response pattern for PTB at <37 weeks and <33 weeks. Uterine artery pulsatility index was increased in early PTB. All patterns of predictors remained the same whether patients with preeclampsia were excluded or included suggesting predictive utility for all causes of PTB. Predictive models all demonstrated good predictive ability with ROC ≥ 0.90.

CONCLUSIONS

PP-13, PAPP-A, and uterine artery Doppler pulsatility index obtained in the first trimester are good predictors of all types of preterm birth, both indicated and spontaneous. Models including first trimester markers combined with maternal characteristics demonstrated good predictive ability and could be investigated for application of targeted prophylactic strategies.

High levels of fetal DNA are associated with increased risk of spontaneous preterm delivery

OBJECTIVE

To assess whether spontaneous preterm delivery can be predicted from the amount of cell free fetal DNA (cffDNA) as determined by routine fetal RHD genotyping at 25 weeks' gestation.

STUDY DESIGN

Cohort study including RhD negative women participating in a routine RHD screening programme. A standard dilution curve was used to quantify the amounts of cffDNA. Values above the 95(th) centile for the study population defined high levels of cffDNA.

RESULTS

We found a highly significant association between preterm delivery and cffDNA levels above the 95(th) centile (p = 0.002). Using logistic regression, women with high levels of cffDNA had an odds ratio of 6.3 (95% confidence interval: 1.9-20.9) for preterm delivery before 37 weeks and an odds ratio for delivery before 34 weeks of 16.6 (95% confidence interval: 3.2-84.7) when adjusting for gestational age at sampling, body mass index and previous miscarriages/terminations of pregnancy.

CONCLUSION

High levels of cffDNA at 25 weeks are associated with increased risk of spontaneous preterm delivery.

The effect of maternal soluble FMS-like tyrosine kinase 1 during pregnancy on risk of preterm delivery

OBJECTIVE

Soluble fms-like tyrosine kinase 1 (sFlt1) is an antiangiogenic protein that is associated with a number of disorders of placental angiogenesis. It has been hypothesized that disruption of placental angiogenesis may contribute to the pathophysiology of preterm delivery (PTD). However, the relationship of PTD risk to variation in sFlt1 levels is not well known. We investigate the relationship between longitudinal variation in maternal serum concentrations of sFlt1 and risk of PTD.

METHODS

Data were collected in a longitudinal cohort study involving 278 pregnant women. Maternal serum sFlt1 concentrations were measured at 6-10, 10-14, 16-20, 22-26, and 32-36 weeks gestation. Data analyses used longitudinal regression models using repeated measures that allow robust inferences from our modest sample size. The outcome was birth prior to 37 weeks gestation.

RESULTS

sFlt1 concentrations were higher in first trimester for preterm compared to term deliveries. This relationship reversed in second trimester because sFlt1 concentrations increased more rapidly across gestation for term deliveries. In Cox proportional hazards analyses, a 2 ng higher sFlt1 concentration across gestation was associated with a hazard ratio of 1.3 (95% CI: 1.1, 1.5) for PTD suggesting the importance of levels in early pregnancy.

CONCLUSION

Elevated maternal serum sFlt1 concentration during pregnancy is associated with increased risk of PTD.

Changes in coagulation and hemodynamics during pregnancy: a prospective longitudinal study of 58 cases

PURPOSE

To investigate changes and establish reference values in coagulation, anticoagulation, fibrinolysis, anti-fibrinolysis and hemodynamics during normal pregnancy.

METHODS

A total of 58 women with singleton pregnancies were recruited. Blood and ultrasound examinations were performed in the 10th-14th, 20th-24th, and 30th-34th weeks of pregnancy. The same examinations were performed in 50 non-pregnant women who were selected as the control group.

RESULTS

Levels of fibrinogen, thrombin time, fibronectin, prothrombin activated fragments 1+2 and thrombomodulin were higher in early pregnancy than those in the control group (P < 0.05). Fibrinogen, prothrombin time, activated partial thromboplastin time, thrombin time, thromboxane B2, prothrombin activated fragments 1+2, thrombomodulin, D-dimer, and plasminogen activator inhibitor-2 were statistically different between the mid pregnancy and the control group (P < 0.05). Meanwhile, fibrinogen, prothrombin time, activated partial thromboplastin time, thrombin time, fibronectin, thromboxane B2, prothrombin activated fragments 1+2, thrombomodulin, and plasminogen activator inhibitor-2 were obviously elevated in late pregnancy as compared with the control group (P < 0.05). Moreover, fibrinogen, thromboxane B2, prothrombin activated fragment 1+2, D-dimer plasminogen, and activator inhibitor-2 gradually increased during pregnancy with some fluctuation. Prothrombin time, activated partial thromboplastin time, thrombin time, international normalized ratio, and thrombomodulin as well as systolic/diastolic ratio, pulsatility index, and resistance index in uterine arteries showed a tendency to decrease in pregnant women.

CONCLUSIONS

Coagulation, anti-coagulation, fibrinolytic and anti-fibrinolytic activities are enhanced and balanced at a higher level during pregnancy. In addition, uterine artery and umbilical artery hemodynamics become more baby friendly (i.e., high flow and low resistance).

The placental factor in spontaneous preterm labor with and without premature rupture of membranes

AIM

The association between infection and inflammatory response in preterm labor (PTL) is well established. Our aim was to elucidate the roles of utero-placental perfusion and fetal component, in PTL.

METHODS

Histopathologic findings in placentas from pregnancies complicated by preterm birth with or without premature rupture of membranes (ROM) (study group) were compared to placentas from pregnancies with delivery >34 weeks, with or without spontaneous ROM (control group). Placental lesions were classified as those consistent with maternal circulation abnormalities, maternal underperfusion, vascular or villous changes, and those consistent with fetal thrombo-occlusive disease, vascular or villous changes. Lesions were analyzed by maternal or fetal origin of inflammatory response.

RESULTS

The study group of 68 women, had a higher rate of vascular lesions than controls (136 women, 26.5% vs. 11%, P=0.005) and of inflammatory lesions of maternal and fetal origin (P<0.001). Within the study group, inflammatory lesions were more common in those with ruptured membrane than in those without (P<0.001).

CONCLUSIONS

Placentas from preterm birth demonstrate vascular lesions of maternal origin, in addition to the known inflammatory process. Preterm premature membrane rupture is associated with an increased rate of inflammatory lesions relative to spontaneous intact membranes-preterm birth, suggesting a different underlying mechanism.

The origins and end-organ consequence of pre-eclampsia

Pre-eclampsia is a multisystem disorder with profound implications for both mother and fetus. Its origins lie in the earliest stages of pregnancy. Abnormal interactions between fetal trophoblast and maternal decidua, including the cells of the maternal immune system, lead to inadequate placental invasion and maternal vascular remodelling. However, abnormal placentation is only one step in the cascade of events that ultimately result in maternal organ dysfunction. Pre-existing maternal conditions predisposing to inflammation and vascular pathology, fetal factors, including multiple gestations and macrosomia, and environmental exposures, including infection, may contribute to the release of placental substances, including anti-angiogenic molecules, into the maternal circulation. These may act directly or indirectly upon the endothelia of end organs, including the kidney, liver and brain. The liberation of reactive oxygen species, cytokines, and microthrombi from damaged endothelia contribute further to organ damage. In studying the normal processes that occur during human placentation and early pregnancy, we will develop a greater understanding of what may go awry in pre-eclampsia. Such research will be crucial in discovering novel biomarkers for prediction of the disorder and, eventually, in finding targets for effective interventions.