Preterm labor: placental pathology and clinical correlation

Air pollution exposure and risk of adverse obstetric and neonatal outcomes among women with type 1 diabetes

AIMS/HYPOTHESIS

Women with type 1 diabetes have increased risk for poor obstetric outcomes. Prenatal air pollution exposure is also associated with adverse outcomes for women and infants. We examined whether women with type 1 diabetes are more vulnerable than other women to pollution-associated risks during pregnancy.

METHODS

In singleton deliveries from the Consortium on Safe Labor (2002-2008), obstetric and neonatal outcomes were compared for women with type 1 diabetes (n = 507) and women without autoimmune disease (n = 204,384). Preconception, trimester, and whole pregnancy average air pollutant exposure (ozone (O₃), carbon monoxide (CO), particulate matter >10 μm (PM₁₀), PM > 2.5 μm (PM_2.5), sulfur dioxide (SO₂), nitrogen oxides (NO_x)) were estimated using modified Community Multiscale Air Quality models. Poisson regression models with diabetes*pollutant interaction terms estimated relative risks and 95% confidence intervals for adverse outcomes, adjusted for maternal characteristics and geographic region.

RESULTS

For whole pregnancy exposure to SO₂, women with type 1 diabetes had 15% increased risk (RR:1.15 95%CI:1.01,1.31) and women without autoimmune disease had 5% increased risk (RR:1.05 95%CI:1.05,1.06) for small for gestational age birth (p_interaction = 0.09). Additionally, whole pregnancy O₃ exposure was associated with 10% increased risk (RR:1.10 95%CI:1.02,1.17) among women with type 1 diabetes and 2% increased risk (RR:1.02 95%CI:1.00,1.04) among women without autoimmune disease for perinatal mortality (p_interaction = 0.08). Similar patterns were observed between PM_2.5 exposure and spontaneous preterm birth.

CONCLUSIONS

Pregnant women with type 1 diabetes may be at greater risk for adverse outcomes when exposed to air pollution than women without autoimmune disease.

Human Papillomavirus E6/E7 Expression in Preeclampsia-Affected Placentae

Whether HPV is causative of pregnancy complications is uncertain. E6 and E7 affect functions underling preeclampsia (PET) in cultured trophoblasts, but whether E6 and E7 is produced in the placenta is uncertain. Here, we investigated whether E6/E7 was expressed in the placentae from pregnancies with PET, other pregnancy complications (fetal growth restriction (FGR) and diabetes mellitus), and uncomplicated pregnancies. Placental tissues collected from two geographical locations were subjected to RNAscope analyses of high- and low- risk E6/E7, and individual HPV types identified using an HPV array. High-risk E6/E7 expression was increased in both PET cohorts, (81% and 86% of patients positive for high-risk HPV DNA compared to 13% of control patients). Various HPV types were identified. Although HPV 18 was the most frequent in all cohorts, the majority of individuals had multiple HPV types (55% of the PET compared to 25% of the control cohort). Further evidence that E6 and E7 is present early when placental pathology underlying preeclampsia is established, is provided with the finding of high-risk E6/E7 in the first-trimester placenta anchoring trophoblast. In conclusion, E6/E7 expression and multiple HPV types were frequent in placentae from preeclampsia-complicated pregnancies.

How Does Preterm Delivery Contribute to the Increased Burden of Cardiovascular Disease? Quantifying the Economic Impact of Cardiovascular Disease in Women with a History of Preterm Delivery

Background: The association between preterm delivery (PTD) and maternal risk of cardiovascular disease (CVD) was demonstrated, but the economic burden of CVD in these women was unknown. Methods: A Markov microsimulation model, comprising no event, postacute coronary event (ACE, including acute myocardial infarction and unstable angina), poststroke, post-ACE and stroke, postheart failure, and death, was constructed to quantify the CVD burden in women with PTD from 2017 to 2066 using the Australian health care system perspective. Both first-ever and recurrent CVD events were accounted for in the model. Population with PTD histories was sourced from Australian Bureau of Statistics and costs of acute hospitalization and long-term management from government websites. Nonmonetary burden as years of life lost (YLL) was compared between women with and without PTD histories. Both dynamic (i.e., new cohort added every cycle) and static (i.e., population was stabilized) approaches were used to measure the CVD burden, with sensitivity analyses examining the robustness of results. Results: The dynamic model showed the total CVD burden caused by PTD as AUD11.4 billion for the next 50 years and the YLL as 0.34/capita, while the static model generated a cost of AUD4.5 billion and the YLL as 0.52/capita. Long-term management cost was the primary cost determinant (AUD9.4 billion and AUD3.7 billion, respectively) in the two models, with the results most sensitive to the discount rate and time horizon. Conclusions: Considering the substantial economic burden, recognizing PTD as a potential risk factor and encouraging women with PTD histories to participate in primary prevention programs would potentially curb the ever-increasing CVD burden.

Omega-3 Fatty Acid-Derived Resolvin D2 Regulates Human Placental Vascular Smooth Muscle and Extravillous Trophoblast Activities

Omega-3 fatty acids are important to pregnancy and neonatal development and health. One mechanism by which omega-3 fatty acids exert their protective effects is through serving as substrates for the generation of specialized pro-resolving lipid mediators (SPM) that potently limit and resolve inflammatory processes. We recently identified that SPM levels are increased in maternal blood at delivery as compared to umbilical cord blood, suggesting the placenta as a potential site of action for maternal SPM. To explore this hypothesis, we obtained human placental samples and stained for the SPM resolvin D2 (RvD2) receptor GPR18 via immunohistochemistry. In so doing, we identified GPR18 expression in placental vascular smooth muscle and extravillous trophoblasts of the placental tissues. Using in vitro culturing, we confirmed expression of GPR18 in these cell types and further identified that stimulation with RvD2 led to significantly altered responsiveness (cytoskeletal changes and pro-inflammatory cytokine production) to lipopolysaccharide inflammatory stimulation in human umbilical artery smooth muscle cells and placental trophoblasts. Taken together, these findings establish a role for SPM actions in human placental tissue.

Vascular Function and Serum Lipids in Women with Spontaneous Preterm Delivery and Term Controls

Background: Spontaneous preterm delivery (sPTD) is associated with a twofold increased risk of future maternal cardiovascular disease. We hypothesized that women with sPTD would demonstrate greater vascular dysfunction postpartum compared to women with term delivery. Materials and Methods: In a case-controlled, matched pilot study, we enrolled 20 women with sPTD (gestation ≤34 weeks), and 20 term control women (gestation ≥39 weeks) were matched for age (±5 years), parity, ethnicity, and route of delivery. Vascular function, serum lipids, C-reactive protein, and interleukin-6 were completed within 24-72 hours postpartum. Statistical analysis included paired t-tests based on match and mixed effects linear regression models and adjusted for potential confounders. Results: The mean age for sPTD and term controls was 33 ± 6 years and 32 ± 6 years, respectively. Women with sPTD had significantly lower augmentation index-75 (24.1% ± 16.1% vs. 39.9% ± 15.2%, p = 0.001) and central pulse pressure (29.1 ± 5.4 mmHg vs. 34.6 ± 4.7 mmHg, p = 0.004), but no difference in pulse wave velocity (5.1 ± 1.6 m/s vs. 5.6 ± 1.5 m/s, p = 0.12) compared to controls. Women with sPTD had significantly lower high-density lipoprotein cholesterol (59.4 ± 12.5 mg/dL vs. 67.6 ± 13.1 mg/dL, p = 0.035) compared to controls. Analysis of chorioamnionitis and magnesium sulfate did not alter the results. Conclusions: Women with sPTD have signs of lower smooth muscle tone in the early postpartum period compared to women with term delivery. Further research is required to understand mechanistic pathways in sPTD and future maternal cardiovascular disease risk.

Risk of prematurity and infant morbidity and mortality by maternal fertility status and plurality

PURPOSE

To evaluate the risk of prematurity and infant mortality by maternal fertility status, and for in vitro fertilization (IVF) pregnancies, by oocyte source and embryo state combinations.

METHODS

Women in 14 States who had IVF-conceived live births during 2004-13 were linked to their infant's birth and death certificates; a 10:1 sample of non-IVF births was selected for comparison; those with an indication of infertility treatment on the birth certificate were categorized as subfertile, all others were categorized as fertile. Risks were modeled separately for the fertile/subfertile/IVF (autologous-fresh only) group and for the IVF group by oocyte source-embryo state combinations, using logistic regression, and reported as adjusted odds ratios (AORs) and 95% confidence intervals (CI).

RESULTS

The study population included 2,474,195 pregnancies. Placental complications (placenta previa, abruptio placenta, and other excessive bleeding) and prematurity were both increased with pregestational and gestational diabetes and hypertension, among subfertile and IVF groups, and in IVF pregnancies using donor oocytes. Both subfertile and IVF pregnancies were at risk for prematurity and NICU admission; IVF infants were also at risk for small-for-gestation birthweight, and subfertile infants had greater risks for neonatal and infant death. Within the IVF group, pregnancies with donor oocytes and/or thawed embryos were at greater risk of large-for-gestation birthweight, and pregnancies with thawed embryos were at greater risk of neonatal and infant death.

CONCLUSIONS

Prematurity was associated with placental complications, diabetes and hypertension, subfertility and IVF groups, and in IVF pregnancies, donor oocytes and/or thawed embryos.

Preterm Delivery and Future Risk of Maternal Cardiovascular Disease: A Systematic Review and Meta-Analysis

Background

Preterm delivery (<37 weeks gestational age) affects 11% of all pregnancies, but data are conflicting whether preterm birth is associated with long‐term adverse maternal cardiovascular outcomes. We aimed to systematically evaluate and summarize the evidence on the relationship between preterm birth and future maternal risk of cardiovascular diseases.

Methods and Results

A systematic search of MEDLINE and EMBASE was performed to identify relevant studies that evaluated the association between preterm birth and future maternal risk of composite cardiovascular disease, coronary heart disease, stroke, and death caused by cardiovascular or coronary heart disease and stroke. We quantified the associations using random effects meta‐analysis. Twenty‐one studies with over 5.8 million women, including over 338 000 women with previous preterm deliveries, were identified. Meta‐analysis of studies that adjusted for potential confounders showed that preterm birth was associated with an increased risk of maternal future cardiovascular disease (risk ratio [RR] 1.43, 95% confidence interval [CI], 1.18, 1.72), cardiovascular disease death (RR 1.78, 95% CI, 1.42, 2.21), coronary heart disease (RR 1.49, 95% CI, 1.38, 1.60), coronary heart disease death (RR 2.10, 95% CI, 1.87, 2.36), and stroke (RR 1.65, 95% CI, 1.51, 1.79). Sensitivity analysis showed that the highest risks occurred when the preterm deliveries occurred before 32 weeks gestation or were medically indicated.

Conclusions

Preterm delivery is associated with an increase in future maternal adverse cardiovascular outcomes, including a 2‐fold increase in deaths caused by coronary heart disease. These findings support the assessment of preterm delivery in cardiovascular risk assessment in women.

Preterm birth with placental evidence of malperfusion is associated with cardiovascular risk factors after pregnancy: a prospective cohort study

OBJECTIVE

Preterm birth (PTB) is associated with excess maternal cardiovascular disease risk. We considered that women with PTB and placental evidence of maternal malperfusion would be particularly affected.

DESIGN

Pregnancy cohort study.

SETTING

Pittsburgh, PA, USA.

POPULATION

Women with PTB (n = 115) and term births (n = 210) evaluated 4-12 years after pregnancy.

METHODS

Cardiometabolic risk markers were compared in women with prior PTB versus term births; pre-eclampsia and growth restriction cases were excluded. Placental evidence of maternal vascular malperfusion (vasculopathy, infarct, advanced villous maturation, perivillous fibrin, intervillous fibrin deposition), acute infection/inflammation (chorioamnionitis, funisitis, deciduitus) and villitis of unknown aetiology (chronic inflammation) was used to classify PTBs.

MAIN OUTCOME MEASURES

Carotid artery intima-media thickness (IMT), fasting lipids, blood pressure (BP) and inflammatory markers measured after delivery.

RESULTS

Women with PTB and malperfusion lesions had higher total cholesterol (+13.5 mg/dl) and systolic BP (+4.0 mmHg) at follow up compared with women with term births, accounting for age, race, pre-pregnancy BMI, and smoking (P < 0.05). Women with PTB and malperfusion accompanied by inflammatory lesions had the most atherogenic profile after pregnancy (cholesterol +18.7, apolipoprotein B + 12.7 mg/dl; all P < 0.05), adjusted for pre-pregnancy features. Carotid IMT was higher in this group (+0.037 cm, P = 0.031) accounting for pre-pregnancy factors; differences were attenuated after adjusting for BP and atherogenic lipids at follow up (+0.027, P = 0.095).

CONCLUSION

PTBs with placental malperfusion were associated with an excess maternal cardiometabolic risk burden in the decade after pregnancy. The placenta may offer insight into subtypes of PTB related to maternal cardiovascular disease.

TWEETABLE ABSTRACT

Preterm births with placental malperfusion may mark women at higher cardiovascular disease risk.

Maternal lipid profile and the relation with spontaneous preterm delivery: a systematic review

BACKGROUND

It is unknown whether an unfavorable (atherogenic) lipid profile and homocysteine level, which could supersede clinical cardiovascular disease, is also associated with an increased risk of spontaneous preterm delivery (sPTD). A systematic review of studies assessing the lipid profile and homocysteine value of women with sPTD compared to women with term delivery in pre-pregnancy and during pregnancy.

METHODS

A systematic search of peer-reviewed articles published between January 1980 and May 2014 was performed using MEDLINE, EMBASE and the Cochrane database. We included case-control and cohort studies that examined triglycerides, high/low density lipoprotein cholesterol, total cholesterol and homocysteine in women with sPTD. Articles were subdivided in pre-pregnancy, first, second and third trimester. Of 708 articles reviewed for eligibility, 14 met our inclusion criteria.

RESULTS AND CONCLUSION

Nine cohort studies and five case-control studies were analyzed, reporting on 1466 cases with sPTD and 11296 controls with term delivery. The studies suggest a possible elevated risk of sPTD in woman with high TG levels, no association of high and low density lipoprotein cholesterol with the risk of sPTD was found. High homocysteine levels are associated with sPTD in the second trimester. The role of triglycerides and homocysteine in sPTD should be explored further.

Protective effect of (±)α-tocopherol on brominated diphenyl ether-47-stimulated prostaglandin pathways in human extravillous trophoblasts in vitro

Brominated diphenyl ether (BDE)-47 is a prevalent flame retardant chemical found in human tissues and is linked to adverse pregnancy outcomes in humans. Because dysregulation of the prostaglandin pathway is implicated in adverse pregnancy outcomes, the present study investigates BDE-47 induction of prostaglandin synthesis in a human extravillous trophoblast cell line, HTR-8/SVneo, examining the hypothesis that BDE-47 increases generation of reactive oxygen species (ROS) to stimulate the prostaglandin response. Treatment with 20 μM BDE-47 significantly increased mRNA expression of prostaglandin-endoperoxide synthase 2 (PTGS2) at 4, 12 and 24 h, and 24-h treatment significantly increased cyclooxygenase (COX)-2 cellular protein expression and prostaglandin E2 (PGE2) concentration in culture medium. The BDE-47-stimulated PGE2 release was inhibited by the COX inhibitors indomethacin and NS398, implicating COX activity. Exposure to 20 μM BDE-47 significantly increased ROS generation as measured by carboxydichlorofluorescein fluorescence, and this response was blocked by cotreatment with the peroxyl radical scavenger (±)-α-tocopherol. (±)-α-Tocopherol cotreatment suppressed BDE-47-stimulated increases of PGE2 release without significant effects on COX-2 mRNA and protein expression, implicating a role for ROS in post-translational regulation of COX activity. Because prostaglandins regulate trophoblast functions necessary for placentation and pregnancy, further investigation is warranted of BDE-47 impacts on trophoblast responses.

Tetrabromobisphenol A activates inflammatory pathways in human first trimester extravillous trophoblasts in vitro

Tetrabromobisphenol A (TBBPA) is a widely used flame retardant. Despite the presence of TBBPA in gestational tissues and the importance of proper regulation of inflammatory networks for successful pregnancy, there is no prior study on the effects of TBBPA on inflammatory responses in gestational tissues. The present study aimed to investigate TBBPA activation of inflammatory pathways, specifically cytokine and prostaglandin production, in the human first trimester placental cell line HTR-8/SVneo. TBBPA enhanced release of interleukin (IL)-6, IL-8, and prostaglandin E2 (PGE2), and suppressed TGF-β release in HTR-8/SVneo cells. The lowest effective concentration was 10 μM TBBPA. A commercial immune response PCR array revealed increased expression of genes involved in inflammatory pathways stimulated by TBBPA in HTR-8/SVneo cells. Because proper regulation of inflammatory mediators in the gestational compartment is necessary for normal placental development and successful pregnancy, further investigation on the impact of TBBPA-stimulated responses on trophoblast function is warranted.

Protective effect of nuclear factor E2-related factor 2 on inflammatory cytokine response to brominated diphenyl ether-47 in the HTR-8/SVneo human first trimester extravillous trophoblast cell line

Polybrominated diphenyl ethers (PBDEs) are widely used flame retardants, and BDE-47 is a prevalent PBDE congener detected in human tissues. Exposure to PBDEs has been linked to adverse pregnancy outcomes in humans. Although the underlying mechanisms of adverse birth outcomes are poorly understood, critical roles for oxidative stress and inflammation are implicated. The present study investigated antioxidant responses in a human extravillous trophoblast cell line, HTR-8/SVneo, and examined the role of nuclear factor E2-related factor 2 (Nrf2), an antioxidative transcription factor, in BDE-47-induced inflammatory responses in the cells. Treatment of HTR-8/SVneo cells with 5, 10, 15, and 20μM BDE-47 for 24h increased intracellular glutathione (GSH) levels compared to solvent control. Treatment of HTR-8/SVneo cells with 20μM BDE-47 for 24h induced the antioxidant response element (ARE) activity, indicating Nrf2 transactivation by BDE-47 treatment, and resulted in differential expression of redox-sensitive genes compared to solvent control. Pretreatment with tert-butyl hydroquinone (tBHQ) or sulforaphane, known Nrf2 inducers, reduced BDE-47-stimulated IL-6 release with increased ARE reporter activity, reduced nuclear factor kappa B (NF-κB) reporter activity, increased GSH production, and stimulated expression of antioxidant genes compared to non-Nrf2 inducer pretreated groups, suggesting that Nrf2 may play a protective role against BDE-47-mediated inflammatory responses in HTR-8/SVneo cells. These results suggest that Nrf2 activation significantly attenuated BDE-47-induced IL-6 release by augmentation of cellular antioxidative system via upregulation of Nrf2 signaling pathways, and that Nrf2 induction may be a potential therapeutic target to reduce adverse pregnancy outcomes associated with toxicant-induced oxidative stress and inflammation.

Patterns of placental pathology in preterm premature rupture of membranes

Inflammation is associated with preterm premature rupture of membranes (PPROM) and adverse neonatal outcomes. Subchorionic thrombi, with or without inflammation, may also be a significant pathological finding in PPROM. Patterns of inflammation and thrombosis may give insight into mechanisms of adverse neonatal outcomes associated with PPROM. To characterize histologic findings of placentas from pregnancies complicated by PPROM at altitude, 44 placentas were evaluated for gross and histological indicators of inflammation and thrombosis. Student's t-test (or Mann-Whitney U-test), χ 2 analysis (or Fisher's exact test), mean square contingency and logistic regression were used when appropriate. The prevalence of histologic acute chorioamnionitis (HCA) was 59%. Fetal-derived inflammation (funisitis and chorionic plate vasculitis) was seen at lower frequency (30% and 45%, respectively) and not always in association with HCA. There was a trend for Hispanic women to have higher odds of funisitis (OR = 5.9; P = 0.05). Subchorionic thrombi were seen in 34% of all placentas. The odds of subchorionic thrombi without HCA was 6.3 times greater that the odds of subchorionic thrombi with HCA (P = 0.02). There was no difference in gestational age or rupture-to-delivery interval, with the presence or absence of inflammatory or thrombotic lesions. These findings suggest that PPROM is caused by or can result in fetal inflammation, placental malperfusion, or both, independent of gestational age or rupture-to-delivery interval; maternal ethnicity and altitude may contribute to these findings. Future studies focused on this constellation of PPROM placental findings, genetic polymorphisms and neonatal outcomes are needed.

Docosahexaenoic acid supplementation early in pregnancy may prevent deep placentation disorders

Uteroplacental ischemia may cause preterm birth, either due to preterm labor, preterm premature rupture of membranes, or medical indication (in the presence of preeclampsia or fetal growth restriction). Uteroplacental ischemia is the product of defective deep placentation, a failure of invasion, and transformation of the spiral arteries by the trophoblast. The failure of normal placentation generates a series of clinical abnormalities nowadays called "deep placentation disorders"; they include preeclampsia, fetal growth restriction, preterm labor, preterm premature rupture of membranes, in utero fetal death, and placental abruption. Early reports suggested that a LC-PUFAs (long chain polyunsaturated fatty acids) rich diet reduces the incidence of deep placentation disorders. Recent randomized controlled trials are inconsistent to show the benefit of docosahexaenoic acid (DHA) supplementation during pregnancy to prevent deep placentation disorders, but most of them showed that DHA supplementation was associated with lower risk of early preterm birth. We postulate that DHA supplementation, early in pregnancy, may reduce the incidence of deep placentation disorders. If our hypothesis is correct, DHA supplementation, early in pregnancy, will become a safe and effective strategy for primary prevention of highly relevant pregnancy diseases, such as preterm birth, preeclampsia, and fetal growth restriction.

The impact of maternal obesity and gestational weight gain on early and mid-pregnancy lipid profiles

OBJECTIVE

The impact of maternal overweight/obesity and excessive weight gain on maternal serum lipids in the first and second trimester of pregnancy was evaluated.

METHODS

Prospective data were collected for 225 women. Maternal serum lipids and fatty acids were measured at <13 weeks and between 24 and 28 weeks. Analyses were stratified by normal weight versus overweight/obese status and excessive versus nonexcessive weight gain.

RESULTS

Overweight/obese women had higher baseline cholesterol (161.3 ± 29.6 vs. 149.4 ± 26.8 mg/dl, P < 0.01), low-density lipoprotein LDL (80.0 ± 19.9 vs. 72.9 ± 18.8 mg/dl, P < 0.01), and triglycerides (81.7 ± 47.2 vs. 69.7 ± 40.3 mg/dl, P = 0.05) when compared to normal weight women, whereas high-density lipoprotein (43.6 ± 10.4 vs. 47.6 ± 11.5 mg/dl, P < 0.01) was lower. However, cholesterol and LDL increased at a higher weekly rate in normal weight women, resulting in higher total cholesterol in normal weight women (184.1 ± 28.1 vs. 176.0 ± 32.1 mg/dl, P = 0.05) at 24-28 weeks. The rate of change in lipid profiles in either group was not affected by excessive weight gain. Overweight/obese women had higher levels of arachidonic acid at both time points.

CONCLUSIONS

Overweight/obese women have significantly more atherogenic lipid profiles than normal weight women during the period of early pregnancy, delineating one physiologic pathway between that could explain differences in pregnancy outcomes normal weight and overweight/obese women.

Involvement of reactive oxygen species in brominated diphenyl ether-47-induced inflammatory cytokine release from human extravillous trophoblasts in vitro

Polybrominated diphenyl ethers (PBDEs) are widely used flame retardant compounds. Brominated diphenyl ether (BDE)-47 is one of the most prevalent PBDE congeners found in human breast milk, serum and placenta. Despite the presence of PBDEs in human placenta, effects of PBDEs on placental cell function are poorly understood. The present study investigated BDE-47-induced reactive oxygen species (ROS) formation and its role in BDE-47-stimulated proinflammatory cytokine release in a first trimester human extravillous trophoblast cell line, HTR-8/SVneo. Exposure of HTR-8/SVneo cells for 4h to 20μM BDE-47 increased ROS generation 1.7 fold as measured by the dichlorofluorescein (DCF) assay. Likewise, superoxide anion production increased approximately 5 fold at 10 and 15μM and 9 fold at 20μM BDE-47 with a 1-h exposure, as measured by cytochrome c reduction. BDE-47 (10, 15 and 20μM) decreased the mitochondrial membrane potential by 47-64.5% at 4, 8 and 24h as assessed with the fluorescent probe Rh123. Treatment with 15 and 20μM BDE-47 stimulated cellular release and mRNA expression of IL-6 and IL-8 after 12 and 24-h exposures: the greatest increases were a 35-fold increased mRNA expression at 12h and a 12-fold increased protein concentration at 24h for IL-6. Antioxidant treatments (deferoxamine mesylate, (±)α-tocopherol, or tempol) suppressed BDE-47-stimulated IL-6 release by 54.1%, 56.3% and 37.7%, respectively, implicating a role for ROS in the regulation of inflammatory pathways in HTR-8/SVneo cells. Solvent (DMSO) controls exhibited statistically significantly decreased responses compared with non-treated controls for IL-6 release and IL-8 mRNA expression, but these responses were not consistent across experiments and times. Nonetheless, it is possible that DMSO (used to dissolve BDE-47) may have attenuated the stimulatory actions of BDE-47 on cytokine responses. Because abnormal activation of proinflammatory responses can disrupt trophoblast functions necessary for placental development and successful pregnancy, further investigation is warranted of the impact of ROS and BDE-47 on trophoblast cytokine responses.

Prior preterm birth and maternal subclinical cardiovascular disease 4 to 12 years after pregnancy

BACKGROUND

We considered that women with prior preterm birth (PTB) would have evidence of subclinical atherosclerosis, endothelial dysfunction, and arterial stiffness.

METHODS

Four to 12 years after pregnancy, blood pressure and fasting lipids were analyzed, and women underwent evaluation, following standardized protocols, of carotid intima-media thickness (IMT), brachial flow-mediated dilation (FMD), and pulse wave velocity (PWV). Women with prior preterm (<37 weeks, n=181) or term births (>= 37 weeks, n=306) were compared. Those with preeclampsia or term small-for-gestational-age (SGA) births were excluded.

RESULTS

Women with a prior preterm vs. term birth had higher blood pressure, on average, and a more atherogenic lipid profile. They also had marginally higher IMT (0.579 standard error [SE] 0.005-vs. 0.567 [0.004] mm, p=0.06), adjusted for body size, demographics, and smoking. IMT differences were greater among those with non-preeclamptic-indicated PTB (0.034 mm, p=0.05) and PTB<34 weeks (0.024 mm, p=0.04) compared to those with term births. These differences appeared to be explained in part by the atherogenic lipid elevations in women with preterm birth. Women with prior PTB<34 weeks tended to have lower FMD, but results were not statistically significant. PWV did not differ according to PTB.

CONCLUSIONS

In the decade following pregnancy, women with non-preeclamptic-indicated PTB or PTB delivered before 34 weeks had higher blood pressure, atherogenic lipids, and IMT compared to women with term births. There may be subgroups of women with a prior PTB with excess cardiovascular risk that is detectable before overt clinical disease.

Preterm birth and future maternal blood pressure, inflammation, and intimal-medial thickness: the CARDIA study

Preterm birth (PTB, <37 weeks) may be a marker of endothelial dysfunction and a proinflammatory phenotype; both are risk factors for cardiovascular disease. We studied 916 women (46% black) with 1181 live births between enrollment in the Coronary Artery Risk Development in Young Adults study (age 18-30 years) and 20 years later. C-reactive protein was measured at years 7, 15, and 20. Interleukin-6 and carotid intima-media thickness, which incorporated the common carotid arteries, bifurcations, and internal carotid arteries, were measured at year 20. Blood pressure, lipids, anthropometrics, and pregnancy events were assessed at all visits. Change in risk factors and differences in inflammatory markers and intima-media thickness according to PTB were evaluated. Women with PTBs (n=226) had higher mean systolic blood pressures before pregnancy (106 versus 105 mm Hg, respectively; P=0.03). Systolic and diastolic blood pressure increased more rapidly over 20 years compared with women with term births (P<0.01 time interaction), even after removing women with self-reported hypertension in pregnancy. Women with PTB versus term births had similar mean intima-media thickness adjusted for age, body mass index, race, lifestyle, and cardiovascular risk factors. C-reactive protein and interleukin-6 did not differ according to PTB. Women with PTB, regardless of hypertension during pregnancy, had higher blood pressure after pregnancy compared with women with term births. In the United States, where rates of PTB are high and race disparities persist, PTB may identify women with higher blood pressure in the years after pregnancy.

First-trimester prediction of preterm birth using ADAM12, PAPP-A, uterine artery Doppler, and maternal characteristics

OBJECTIVE

The objective of this study was to estimate the efficiency of first-trimester a disintegrin and metalloprotease 12 (ADAM12), pregnancy-associated plasma protein A (PAPP-A), uterine artery Doppler, and maternal characteristics in the prediction of preterm birth (PTB).

METHODS

This was a prospective cohort study of patients presenting for first-trimester aneuploidy screening. Maternal serum ADAM12 and PAPP-A levels were measured by immunoassay, and mean uterine artery Doppler pulsatility indices were calculated. The primary outcome was PTB <34 weeks' gestation, and the secondary outcome was PTB <37 weeks' gestation. Logistic regression was used to model the prediction of PTB using ADAM12, PAPP-A, uterine artery Doppler, and maternal characteristics, individually and in combination. Sensitivity, specificity, and area under the receiver-operating characteristic curves were compared between models.

RESULTS

Of 578 patients, 36 (6.2%) delivered <34 weeks, and 78 (13.5%) delivered <37 weeks. For a 20% fixed false positive rate, ADAM12, PAPP-A, and uterine artery Doppler identified 58%, 52%, and 62% of patients with PTB <34 weeks and 42%, 48%, and 50% of patients with PTB <37 weeks, respectively. Combining these first-trimester parameters did not improve the predictive efficiency of the models.

CONCLUSION

First-trimester ADAM12, PAPP-A, and uterine artery Doppler are each modestly predictive of PTB; however, combinations of these parameters do not further improve their screening efficiency.

Periconceptional multivitamin use and risk of preterm or small-for-gestational-age births in the Danish National Birth Cohort

BACKGROUND

The intake of periconceptional multivitamins may decrease the risk of preterm births (PTBs) or small-for-gestational-age (SGA) births.

OBJECTIVE

We related the timing and frequency of periconceptional multivitamin use to SGA births and PTBs and its clinical presentations (ie, preterm labor, premature rupture of membranes, and medical induction).

DESIGN

Women in the Danish National Birth Cohort (n = 35,897) reported the number of weeks of multivitamin use during a 12-wk periconceptional period. Cox regression was used to estimate the relation between any multivitamin use and PTBs (<37 wk) or SGA births (birth weight adjusted for gestational age >2 SDs below the mean on the basis of fetal growth curves). The timing (preconception and postconception) and frequency of use were also analyzed. Regular users (4-6 wk) and partial users (1-3 wk) in each period were compared with nonusers.

RESULTS

The association between periconceptional multivitamin use and PTBs varied according to prepregnancy overweight status (P-interaction = 0.07). Regular preconception and postconception multivitamin use in women with a prepregnancy BMI (in kg/m(2)) <25 was associated with reduced risks of a PTB (HR: 0.84; 95% CI: 0.73, 0.95) and preterm labor (HR: 0.80; 95% CI: 0.69, 0.94). No similar associations were shown for overweight women. The adjusted risk of an SGA birth was reduced in multivitamin users regardless of their prepregnancy BMI (HR: 0.83; 95% CI: 0.73, 0.95), with the strongest association in regular users in the postconception period.

CONCLUSION

Regular periconceptional multivitamin use was associated with reduced risk of SGA births and PTBs in nonoverweight women.

Placental bed disorders in preterm labor, preterm PROM, spontaneous abortion and abruptio placentae

Failure of physiologic transformation of the spiral arteries has been studied using placental bed biopsies in several obstetrical syndromes. Contrary to what was originally believed, this lesion is not restricted to preeclampsia and/or intrauterine growth restriction. A review of published evidence indicates that failure of physiologic transformation can be observed in women with spontaneous second trimester abortions, preterm labor with intact membranes, preterm prelabor rupture of membranes and abruptio placentae. Therefore, disorders of deep placentation are present in a wide range of complications of pregnancy, emphasizing the importance of understanding the physiology and pathology of transformation of the spiral arteries. We propose that changes in the population and function of immunocytes at the maternal-fetal interface can be part of the mechanism of disease of obstetrical disorders, and this requires further investigation.

Early or recurrent preterm birth and maternal cardiovascular disease risk

PURPOSE

Preterm birth (PTB) has been associated with a later increased risk of maternal cardiovascular disease (CVD). We hypothesized a more pronounced relation between early or recurrent PTB and maternal CVD risk.

METHODS

We related PTB severity (earlier gestational age at delivery) and recurrence (>/=2) among women with births from 1973-1983 in Denmark (n = 427,765) to maternal CVD morbidity or mortality (1977-2006). Birth data were linked to CVD hospitalizations and deaths identified in national registers and data were analyzed using Cox proportional hazards models.

RESULTS

Women with a prior PTB had excess CVD after adjustment for age, parity, and education (hazard ratio [HR] = 1.36 [95% confidence interval (CI): 1.31, 1.41]). This was only modestly attenuated when women with preeclampsia or small for gestational age births were excluded, and the relationship was stronger for CVD mortality (HR = 1.98 [1.73, 2.26]). Recurrent PTB was associated with higher CVD morbidity compared to women with one PTB, particularly for ischemic events (HR = 1.78 [1.40, 2.27] vs. 1.22 [1.09, 1.36]). Risk was similarly elevated among women with early, moderate, and late PTB. Sensitivity analysis suggested that confounding by smoking only partly explained these associations.

CONCLUSIONS

Women with PTB, especially recurrent PTB, were at increased risk for CVD, suggesting common causes of these conditions.

Prepregnancy lipids related to preterm birth risk: the coronary artery risk development in young adults study

CONTEXT

Preterm birth is associated with maternal cardiovascular risk, but mechanisms are unknown.

OBJECTIVE

We considered that dyslipidemia may predispose women to both conditions and that prepregnancy lipids may be related to preterm birth risk. We hypothesized that low or high prepregnancy plasma lipids would be associated with preterm birth.

DESIGN, SETTING, AND PARTICIPANTS

A total of 1010 women (49% black) enrolled in the multicenter, prospective Coronary Artery Risk Development in Young Adults study with at least one singleton birth during 20 yr of follow-up were evaluated.

MAIN OUTCOME MEASURE

Postbaseline preterm births less than 34 wk or 34 to less than 37 wk vs. greater than 37 wk gestation.

RESULTS

We detected a U-shaped relationship between prepregnancy cholesterol concentrations and preterm birth risk. Women with prepregnancy cholesterol in the lowest quartile compared with the second quartile (<156 vs. 156-171 mg/dl) had an increased risk for preterm birth 34 to less than 37 wk (odds ratio 1.86; 95% confidence interval 1.10, 3.15) and less than 34 wk (odds ratio 3.04; 1.35, 6.81) independent of race, age, parity, body mass index, hypertension during pregnancy, physical activity, and years from measurement to birth. Prepregnancy cholesterol in the highest quartile (>195 mg/dl) was also associated with preterm birth less than 34 wk among women with normotensive pregnancies (odds ratio 3.80; 95% confidence interval 1.07, 7.57). There were no associations between prepregnancy triglycerides, low-density lipoprotein cholesterol, or high-density lipoprotein cholesterol and preterm birth.

CONCLUSIONS

Both low and high prepregnancy cholesterol were related to preterm birth risk. These may represent distinct pathways to the heterogeneous outcome of preterm birth. Additional studies are needed to elucidate mechanisms that link low or high cholesterol to preterm birth and later-life sequelae.

Activation of the fibrinolytic cascade early in pregnancy among women with spontaneous preterm birth

OBJECTIVE

To evaluate the association of early pregnancy concentrations of thrombin-antithrombin III complex with subsequent spontaneous preterm birth.

METHODS

In a nested case-control study, thrombin-antithrombin III complex was measured in plasma before 20 weeks of gestation (mean 9.9 weeks) among women without chronic conditions, preeclampsia, or growth restriction. C-reactive protein and non-high-density lipoprotein cholesterol were also measured. Women with spontaneous preterm birth before 34 weeks of gestation (n=29) and 34 weeks to 36 weeks of gestation (n=72) were compared with women with term births occurring at or after 37 weeks (n=219). Polychotomous logistic regression was used to relate elevated thrombin-antithrombin III complex (greater than 5.5 ng/mL), dyslipidemia (non-high-density lipoprotein cholesterol greater than the 90th percentile), and inflammation (C-reactive protein at or above 8 micrograms/mL) to risk of spontaneous preterm birth subtypes.

RESULTS

Women with spontaneous preterm birth compared with term births had elevated thrombin-antithrombin III complex (P=.02), and they were more likely to have a thrombin-antithrombin III complex greater than 5.5 ng/mL (P<.01). Women with thrombin-antithrombin III complex in the highest compared with lowest quartile had a 4.6-fold (95% confidence interval 1.3-15.8) increased risk for spontaneous preterm birth before 34 weeks of gestation, adjusted for body mass index, race, inflammation, dyslipidemia, and gestational age at sampling. There was a dose-response trend between thrombin-antithrombin III complex and spontaneous preterm birth before 34 weeks (P<.01) and 34 to 36 weeks (P=.03).

CONCLUSION

There is evidence of early pregnancy systemic fibrinolysis among women with spontaneous preterm birth before 34 weeks of gestation independent of inflammation and dyslipidemia, perhaps secondary to microvascular injury.

LEVEL OF EVIDENCE

II.

Early pregnancy lipid concentrations and spontaneous preterm birth

OBJECTIVE

Women who deliver preterm infants may be at increased risk for cardiovascular disease, perhaps related to dyslipidemia.

STUDY DESIGN

In a nested case control study of women with spontaneous preterm birth, cholesterol, high-density lipoprotein, low-density lipoprotein, and triglycerides were evaluated. Lipid concentrations and gestational changes, as well as risk for preterm birth, were evaluated in women who delivered <34 (n = 23), >or=34-<37 (n = 67), and >or=37 weeks (n = 199).

RESULTS

High cholesterol or triglycerides <or=15 weeks were associated with a 2.8-fold (1.0-7.9) and 2.0-fold (1.0-3.9) increased risk for preterm birth <34 weeks and >or=34-<37 weeks, respectively. Overweight women who delivered <34 weeks had particularly elevated early pregnancy concentrations of cholesterol and low-density lipoprotein; lean women with moderate preterm birth had elevated triglycerides. There was a reduced triglyceride response in the first half of pregnancy among women who delivered <34 weeks.

CONCLUSION

Our results indicate the presence of dyslipidemia in women with spontaneous preterm birth.

Examining the relationship between positive mid-gestational fetal fibronectin assays and histological evidence of acute placental inflammation

AIMS

Both acute placental inflammation and positive mid-gestational cervico-vaginal fetal fibronectin assays have been independently correlated with preterm delivery. We conducted this study to examine the relationship between positive mid-gestational fetal fibronectin (fFN) assays and histological evidence of acute placental inflammation at delivery among women presenting with symptomatic preterm labor.

METHODS

This retrospective chart review included women who underwent cervico-vaginal fFN testing for preterm contractions between 24-34 weeks gestation and also had placental histological analysis after delivery. Women with a multiple gestation, cerclage, preterm premature rupture of membranes, intercourse or vaginal bleeding within 24 h before the assay were excluded. The primary outcome was histological evidence of acute placental inflammation defined as acute chorioamnionitis, acute deciduitis, funisitis, or microabscess formation.

RESULTS

Of 82 women who met all study inclusion criteria, 45% were fFN positive. Women with positive assays were no more likely to have histological evidence of acute inflammation noted at birth than women with negative assays (45% vs. 26%, P=0.07). The assay had a sensitivity of 58.6%, specificity of 62.3%, positive predictive value of 46.0%, and negative predictive value of 73.3% for predicting acute inflammation at delivery.

CONCLUSIONS

No association exists between positive fetal fibronectin assays and acute histologic placental inflammation at birth.

Intra- and interobserver agreement and statistical clustering of placental histopathologic features relevant to preterm birth

OBJECTIVE

Many previous studies of agreement in identifying placental histopathologic lesions have been based on small sample sizes, and none has examined whether individual histologic features cluster robustly together within and between observers.

STUDY DESIGN

We studied 767 placental specimens from case-control studies of preterm birth and preeclampsia nested within a prospective cohort of pregnant women recruited from 4 large Montreal maternity hospitals. The specimens were fixed, embedded, stained, and examined using a standardized protocol; a 10% random sample (n = 81) was then blindly reexamined at least 6 months later by the same pathologist and a second pathologist.

RESULTS

Intra- and interobserver agreement were high (kappa > or = 0.50) for membrane inflammation, funisitis, and umbilical cord vasculitis, and these 3 features were robustly clustered statistically, consistent with an underlying mechanism of ascending infection. Agreement and clustering were also high or moderate for features of placental underperfusion: infarction, decidual vasculopathy, and syncytial knotting.

CONCLUSION

Our results should help researchers to interpret future findings relating placental histopathology to preterm birth, preeclampsia, and other adverse pregnancy outcomes, and to their etiologic determinants and causal pathways.

Adeno-associated virus-2 (AAV-2) causes trophoblast dysfunction, and placental AAV-2 infection is associated with preeclampsia

Shallow invasion by extravillous trophoblast cells into the uterine wall reduces placental perfusion and causes placental dysfunction, but the one or more causes of shallow placental invasion are unknown. We hypothesized that infection with adeno-associated virus-2 (AAV-2) inhibits trophoblast invasion and is associated with preeclampsia, which is a common obstetric complication resulting from placental dysfunction. We determined that transformed extravillous trophoblast (HTR-8/SVneo) cells were susceptible to AAV-2 infection in the presence or absence of adenovirus, which provides helper function for AAV-2 replication, and that AAV-2 infection reduced invasion of HTR-8/SVneo cells through an extracellular matrix before cytopathic effects were detected. In a case-control study, AAV-2 DNA was found more frequently in trophoblast cells from cases of severe preeclampsia (22/40) than from normal term deliveries (5/27, P = 0.002). These results indicate that AAV-2 infection is a previously unidentified cause of placental dysfunction. Additional studies to determine the susceptibility of extravillous trophoblast to other viruses, and the mechanisms by which viral infection impairs placental function, are warranted.

Maternal smoking and causes of very preterm birth

BACKGROUND

Smoking increases the risk of preterm birth. The present study was made to elucidate the relation of smoking to causes of very preterm birth.

METHODS

In a case-control study on all very preterm births in two regions of Stockholm 1988-1992, prospectively collected data were extracted from antenatal and delivery records on smoking, other maternal characteristics, pregnancy complications, and causes of preterm birth. Cases were live single births with a gestational age of < or =32 weeks and 0 days, and controls were live singletons delivered at 37 weeks or later (n = 295, respectively). Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated with logistic regression.

RESULTS

Compared with non-smokers, adjusted ORs of very preterm birth among moderate smokers (1-9 cigarettes per day) and heavy smokers (> or =10 cigarettes per day) were 1.4 (95% CI 0.8-2.4) and 2.9 (95% CI 1.5-5.7), respectively. Compared with non-smokers, risk of preterm labor was increased among moderate and heavy smokers [ORs 1.9 (95% CI 1.0-3.6) and 2.6 (95% CI 1.1-1.6), respectively]. These risks remained essentially unchanged in women without an identifiable cause of preterm labor ('idiopathic preterm labor'). Smoking was also associated with dose-dependent increases in risks of preterm birth due to preterm premature rupture of membranes and late pregnancy bleedings. There was no association between smoking and risk of very preterm birth caused by hypertensive diseases.

CONCLUSIONS

Smoking increases the risk of very preterm birth caused by preterm labor (including idiopathic preterm labor), preterm premature rupture of membranes, and late pregnancy bleedings.

Spectral Doppler Index Mapping of the Umbilicoplacental Circulation and Pregnancy Outcome

OBJECTIVE

To determine the value of Doppler measurements obtained by a new multigate Doppler modality, the spectral Doppler index mapping (SDIM) technique, to predict adverse outcome among pregnant women with normal conventional umbilical artery (UA) Doppler indices.

DESIGN

A cross-sectional prospective cohort study.

SUBJECTS

183 women with well-dated singleton pregnancies who underwent prenatal ultrasound examination between 18 and 40 weeks of gestation were included in the study. At the time of the initial Doppler examination, all patients had normal UA and uterine artery Doppler indices, size appropriate for gestational age, no evidence of fetal anomalies or fetal distress.

METHODS

SDIM data included the distribution curves of the pulsatility indices (PI) as well as the mean of the PI detected in the placenta and in the umbilical cord. The mean PI values were also calculated using conventional spectral Doppler sonography. Logistic regression analysis was used to control for gestational age while assessing various Doppler variables in predicting outcome.

RESULTS

Adverse outcomes occurred in 26.6% of the pregnancies. In pregnancies with adverse outcome, the umbilicoplacental PI gradient was significantly lower (0.10 vs. 0.28, p < 0.003), the maximum intraplacental PI value was higher (1.28 vs. 1.16, p = 0.031), and there was a greater proportion with skewed UA distribution curves. Using forward stepwise logistic regression to compare the predictive value of the conventional Doppler ultrasound with SDIM, we found that the most accurate predictors of adverse outcome were the maximum intraplacental PI value (p < 0.028), skewed distributions (p = 0.002) and the gradient between the umbilical and intraplacental PI distributions (p = 0.006).

CONCLUSIONS

Our results suggest that the SDIM system may enhance the ability of Doppler technology to predict obstetrical outcomes in patients with normal UA Doppler indices.

Failure of physiologic transformation of the spiral arteries in patients with preterm labor and intact membranes

OBJECTIVE

The purpose of this study was to determine whether abnormal placentation (defined as the failure of physiologic transformation of spiral arteries) is present in patients with preterm labor and intact membranes who delivered a preterm neonate.

STUDY DESIGN

A cross-sectional study was conducted to examine the histopathologic findings in the placental bed and placenta of patients with preterm labor and intact membranes (n=27), preeclampsia (n=43), and healthy pregnant women at term (n=103). Immunohistochemistry studies with cytokeratin 7 and periodic acid-Schiff were used to detect trophoblast and fibrinoid, respectively, and diagnose the failure of physiologic transformation of the spiral arteries.

RESULTS

The mean percentage of spiral arteries with failure of physiologic transformation in the myometrium was significantly higher in patients with preterm labor and preeclampsia than in normal pregnant women at term (P=.0004 and P<.0001, respectively). Similar findings were observed in the decidual segment of spiral arteries within the placental bed (P=.001 and P<.0001). In contrast, the mean percentage of the spiral arteries with failure of physiologic transformation in the decidua of the basal plate was not significantly different between patients with preterm labor and normal pregnant women (P=.17).

CONCLUSION

Failure of physiologic transformation of the spiral arteries in the myometrial and decidual segments of the placental bed is frequent in patients with preterm labor and intact membranes.

Pregnancy outcomes and community health: the POUCH study of preterm delivery

In light of the social/ethnic disparity in preterm delivery (PTD) rates, the Pregnancy Outcomes and Community Health (POUCH) Study takes a broad view of the determinants of PTD by attempting to link underlying biological and psychosocial factors. The relationships between placental pathology, maternal biomarkers, and antecedent psychosocial factors are evaluated in three hypothesised pathways of PTD - one characterised primarily by infection, one by maternal vascular disease, and one by premature elevations in corticotropin releasing hormone in the absence of histological evidence of placental pathology. Within each pathway, an emphasis is placed on understanding the roles of stress and of maternal serum alpha-fetoprotein, an early biomarker associated with PTD. The POUCH Study enrolls pregnant women from five Michigan communities. Information about these women and their environments is gathered through detailed interviews and collection of biological samples including hair, urine, saliva, blood, vaginal fluid, and vaginal smear at 15-26 weeks of gestation. We have chosen to focus on the second trimester--a time when pathological processes may have evolved to a detectable stage, but generally before the onset of biological changes that accompany labour. This focus is consistent with the long-range goal of early detection/intervention and prevention of PTD.

Regulation of uterine contraction: mechanisms in preterm labor

Preterm labor (PTL) is defined as uterine irritability accompanied by cervical dilation and/or effecement that occurs before 37 weeks gestation. In most cases, PTL becomes preterm delivery (PTD), accounting for 8% to 10% of births in the United States. Fetuses born before 37 weeks' gestation are at risk for a multitude of health and developmental problems. Most perinatal morbidity and mortality in the United States are caused by PTL. It is a costly problem, in both monetary and human terms. Although some risk factors have been identified, they by no means identify, in advance, every case of PTL and PTD. Despite the understandable emphasis on attempts to find and test risk factors that predict PTL, the ultimate benefit--preventing PTD--will come only from an understanding of the physiologic mechanisms of parturition and how to halt those processes when they occur too early. This article reviews current approaches to preventing PTD, describes the biology of myometrial contraction, and discusses recent progress from several laboratories including the authors' that may shed light on approaches to inhibit uterine contractility in the setting of PTL.