Preterm delivery and risk of subsequent cardiovascular morbidity and type-II diabetes in the mother

Assessing the causal association of pregnancy complications with diabetes and cardiovascular disease

Background

To the best of our knowledge, numerous observational studies have linked pregnancy complications to increased risks of diabetes and cardiovascular disease (CVD), causal evidence remains lacking. Our aim was to estimate the association of adverse pregnancy outcomes with diabetes and cardiovascular diseases.

Methods

A two-sample Mendelian randomization (MR) analysis was employed, which is not subject to potential reverse causality. Data for pregnancy complications were obtained from the FinnGen consortium. For primary analysis, outcome data on diabetes, related traits, stroke, and coronary heart disease (CHD) were extracted from the GWAS Catalog, MAGIC, MEGASTROKE, and CARDIoGRAMplusC4D consortium. The MAGIC and UKB consortium datasets were used for replication and meta-analysis. Causal effects were appraised using inverse variance weighted (IVW), weighted median (WM), and MR-Egger. Sensitivity analyses were implemented with Cochran's Q test, MR-Egger intercept test, MR-PRESSO, leave-one-out (LOO) analysis and the funnel plot.

Results

Genetically predicted gestational diabetes mellitus (GDM) was causally associated with an increased diabetes risk (OR=1.01, 95% CI=1-1.01, P<0.0001), yet correlated with lower 2-hour post-challenge glucose levels (OR=0.89, 95% CI=0.82-0.97, P=0.006). Genetic liability for pregnancy with abortive outcomes indicated decreased fasting insulin levels (OR=0.97, 95% CI=0.95-0.99, P=0.02), but potentially elevated glycated hemoglobin levels (OR=1.02, 95% CI=1.01-1.04, P=0.01). Additionally, hypertensive disorders in pregnancy was tentatively linked to increased risks of stroke (OR=1.11, 95% CI=1.04-1.18, P=0.002) and CHD (OR=1.3, 95% CI=1.2-1.4, P=3.11E-11). Gestational hypertension might have a potential causal association with CHD (OR=1.11, 95% CI=1.01-1.22, P=0.04). No causal associations were observed between preterm birth and diabetes, stroke, or CHD.

Conclusion

The findings of this study provide genetic evidence that gestational diabetes, pregnancy with abortive outcomes, and hypertensive disorders in pregnancy may serve as early indicators for metabolic and cardiovascular risks. These insights are pivotal for the development of targeted screening and preventive strategies.

Maternal Hemodynamics from Preconception to Delivery: Research and Potential Diagnostic and Therapeutic Implications: Position Statement by Italian Association of Pre-Eclampsia and Italian Society of Perinatal Medicine

OBJECTIVE

 The Italian Association of Preeclampsia (AIPE) and the Italian Society of Perinatal Medicine (SIMP) developed clinical questions on maternal hemodynamics state of the art.

STUDY DESIGN

 AIPE and SIMP experts were divided in small groups and were invited to propose an overview of the existing literature on specific topics related to the clinical questions proposed, developing, wherever possible, clinical and/or research recommendations based on available evidence, expert opinion, and clinical importance. Draft recommendations with a clinical rationale were submitted to 8th AIPE and SIMP Consensus Expert Panel for consideration and approval, with at least 75% agreement required for individual recommendations to be included in the final version.

RESULTS

 More and more evidence in literature underlines the relationship between maternal and fetal hemodynamics, as well as the relationship between maternal cardiovascular profile and fetal-maternal adverse outcomes such as fetal growth restriction and hypertensive disorders of pregnancy. Experts agreed on proposing a classification of pregnancy hypertension, complications, and cardiovascular states based on three different hemodynamic profiles depending on total peripheral vascular resistance values: hypodynamic (>1,300 dynes·s·cm-5), normo-dynamic, and hyperdynamic (<800 dynes·s·cm-5) circulation. This differentiation implies different therapeutical strategies, based drugs' characteristics, and maternal cardiovascular profile. Finally, the cardiovascular characteristics of the women may be useful for a rational approach to an appropriate follow-up, due to the increased cardiovascular risk later in life.

CONCLUSION

 Although the evidence might not be conclusive, given the lack of large randomized trials, maternal hemodynamics might have great importance in helping clinicians in understanding the pathophysiology and chose a rational treatment of patients with or at risk for pregnancy complications.

KEY POINTS

· Altered maternal hemodynamics is associated to fetal growth restriction.. · Altered maternal hemodynamics is associated to complicated hypertensive disorders of pregnancy.. · Maternal hemodynamics might help choosing a rational treatment during hypertensive disorders..

Maternal cobalt concentration and risk of spontaneous preterm birth: the role of fasting blood glucose and lipid profiles

Introduction

Spontaneous preterm birth (SPB) is a significant cause of neonatal mortality, yet its etiology remains unclear. Cobalt, an essential trace element, might be a risk factor for SPB. This study aims to investigate the relationship between maternal serum cobalt concentration and SPB, and to clarify the role of blood lipids and fasting blood glucose (FBG) in this relationship.

Methods

We conducted a nested case-control study within the Beijing Birth Cohort Study. Serum samples were obtained from 222 pregnant women with SPB and 224 controls during the first (7-13 weeks of pregnancy) and third trimesters (32-42 weeks of pregnancy). Serum cobalt concentration was determined using inductively coupled plasma mass spectrometry (ICP-MS). Fasting blood glucose and lipids levels were detected using a fully automated biochemical immunoassay instrument. Logistic regression models and linear regression models were established to explore the association between serum cobalt concentration and the risk of SPB in pregnant women, and to test the mediating effect of fasting blood glucose (FBG) and lipids.

Results

We found that the serum cobalt concentration in mothers with SPB and controls was similar in the first trimester, with values of 0.79 (0.58-1.10) ng/mL and 0.75 (0.51-1.07) ng/mL, respectively. However, in the third trimester, the cobalt concentration increased to 0.88 (0.59-1.14) ng/mL and 0.84 (0.52-1.19) ng/mL, respectively. In the logistic regression model, when considering the third trimester of pregnancy, after adjusting for ethnicity, pre-pregnancy body mass index (BMI), maternal age, education, income, and parity, it was observed that the medium level of cobalt concentration (0.63-1.07 ng/ml) had a negative correlation with the risk of SPB. The odds ratio (OR) was 0.56, with a 95% confidence interval of 0.34-0.90 ng/mL and a p-value of 0.02. This suggests that cobalt in this concentration range played a protective role against SPB. Additionally, it was found that FBG in the third trimester of pregnancy had a partial intermediary role, accounting for 9.12% of the association. However, no relationship between cobalt and SPB risk was found in the first trimester.

Conclusion

During the third trimester, intermediate levels of maternal cobalt appear to offer protection against SPB, with FBG playing a partial mediating role. To further clarify the optimal cobalt concentrations during pregnancy for different populations, a multi-center study with a larger sample size is necessary. Additionally, exploring the specific mechanism of FBG's mediating role could provide valuable insights for improving the prevention of SPB.

Adverse pregnancy outcomes and risk of type 2 diabetes in postmenopausal women

BACKGROUND

Although gestational diabetes mellitus and delivering high-birthweight infants are known to predict a higher risk of future type 2 diabetes mellitus, the association of hypertensive disorders of pregnancy and other adverse pregnancy outcomes with type 2 diabetes mellitus is not well established.

OBJECTIVE

This study aimed to examine the associations between different types of adverse pregnancy outcomes and incident type 2 diabetes mellitus among postmenopausal women.

STUDY DESIGN

The Women's Health Initiative, a nationwide cohort of postmenopausal women, collected self-reported history of adverse pregnancy outcomes, including gestational diabetes mellitus, hypertensive disorders of pregnancy, preterm birth, and delivering low- birthweight (<2500 g) or high-birthweight (>4500 g) infants. Participants were followed up annually for self-reported incident type 2 diabetes mellitus treated with medication from baseline (1993-1998) to March 2021. This study used logistic regression to examine the associations of any and individual adverse pregnancy outcomes with diabetes mellitus. Stratified analyses were performed to assess effect modification by body mass index, race and ethnicity, education, parity, breastfeeding, and age at first birth.

RESULTS

This analysis included 49,717 women without a history of diabetes mellitus at enrollment who had a least 1 pregnancy and responded to the questionnaire about adverse pregnancy outcomes. After adjusting for body mass index, demographic, lifestyle, and reproductive factors, gestational diabetes mellitus (odds ratio, 2.26; 95% confidence interval, 1.94-2.63), high birthweight (odds ratio, 1.30; 95% confidence interval, 1.18-1.44), and hypertensive disorders of pregnancy (odds ratio, 1.18; 95% confidence interval, 1.08-1.30) were independently associated with higher odds of type 2 diabetes mellitus, whereas preterm birth and low birthweight were not associated with diabetes mellitus risk. A history of ≥2 adverse pregnancy outcomes was associated with higher odds of type 2 diabetes mellitus (odds ratio, 1.55; 95% confidence interval, 1.28-1.88). This study further observed higher odds of type 2 diabetes mellitus (odds ratio, 3.69; 95% confidence interval, 2.38-5.70) among women with a history of both gestational diabetes mellitus and hypertensive disorders of pregnancy than those without any adverse pregnancy outcomes.

CONCLUSION

Postmenopausal women with a history of gestational diabetes mellitus, those delivering high-birthweight infants, or those with hypertensive disorders of pregnancy are at risk of future type 2 diabetes mellitus. In addition, women with ≥2 conditions had an augmented risk and might be prioritized for screening and prevention efforts for type 2 diabetes mellitus.

Association between preterm delivery and subsequent maternal risk of hypertension and type 2 diabetes mellitus in a UK population-based retrospective cohort study

OBJECTIVES

Women with a history of preterm delivery (PTD) are at higher risk of developing cardiovascular diseases (CVD) later in life. However, it is not well established whether PTD is associated with CVD risk factors, hypertension and type 2 diabetes mellitus (T2DM). Therefore, in this study, we examined the associations between PTD compared with term delivery and subsequent risk of hypertension and T2DM.

DESIGN

Retrospective matched population-based open cohort study.

SETTING

Clinical Practice Research Datalink GOLD data in the UK.

PARTICIPANTS

A total of 3335 18-49-year-old women with preterm delivery were matched by age and region to 12 634 without a record of preterm delivery.

PRIMARY OUTCOME MEASURES

Outcomes of interest were newly diagnosed hypertension or T2DM at least 6 months after delivery. During the study period (January 2000-December 2019), hypertension or T2DM events in the medical records of women with (exposed) and without (unexposed) preterm delivery were compared. HR and 95% CI were estimated using Cox proportional hazards models adjusted for potential confounders.

RESULTS

Over a median follow-up period of 5.11 (IQR 2.15-9.56) years, the HRs for hypertension in women who delivered preterm compared with women who delivered at term were 1.42 (95%CI 1.09 to 1.80) and 1.18 (95%CI 0.90 to 1.56) in the unadjusted and adjusted models, respectively. For T2DM, over a median follow-up period of 5.17 (IQR 2.18-9.67) years, the HRs in women who delivered preterm compared with those who delivered at term were 1.67 (95%CI 1.12 to 2.48) and 1.10 (95%CI 0.72 to 1.68) in the unadjusted and adjusted models, respectively.

CONCLUSION

We found no independent effect of preterm delivery on risk of hypertension or type 2 diabetes in this study. While significant associations were observed in unadjusted analyses, associations were lost after adjustment and may be attributable to other reproductive complications. Additional studies are needed to confirm these findings.

Adverse pregnancy outcomes and future risk of heart failure

PURPOSE OF REVIEW

Cardiovascular disease (CVD) is the leading cause of death in women. Women with history of adverse pregnancy outcomes (APOs) have approximately two-fold risk of future CVD, but until recently the association with future heart failure (HF) was unclear. Here, we summarize evidence for associations of APOs with HF, potential underlying mechanisms, and future directions for clinical translation.

RECENT FINDINGS

Women with history of hypertensive disorders of pregnancy (HDPs) have roughly two-fold risk of future HF compared with other parous women even after accounting for interval development of coronary artery disease. The HDPs portend heightened risk of HF with both reduced and preserved ejection fraction. Gestational diabetes mellitus (GDM) and other APOs such as preterm delivery, small-for-gestational-age delivery, and placental abruption may also confer additional risk for HF development. Possible underlying mechanisms linking APOs to HF include shared upstream risk factors and genetics, accelerated development of cardiometabolic risk factors postpartum, persistent endothelial and microvascular dysfunction, and impaired natriuretic peptide signaling.

SUMMARY

History of APOs, including HDPs and GDM, confer increased risk for development of HF years after delivery. Further research is needed to define strategies to optimize prepregnancy and postpartum cardiovascular health toward HF prevention.

Preterm Delivery and Increased Risk of Recurrent Cardiovascular Events in Australian Women

Background: Women with a history of preterm delivery (PTD) have significantly increased risk of experiencing cardiovascular disease (CVD) later in life. However, the risk of long-term recurrence of CVD in this population remains unknown. Materials and Methods: The study was based on a cohort of Victorian women who had a singleton birth between 1999 and 2008. The primary outcome was a CVD event resulting in an Emergency Department visit/hospitalization or death. Women who do not have a PTD during the study period were adopted as the comparator. The Andersen and Gill model, which generalizes the Cox proportional hazards regression model, was used for the analysis of recurrent CVD, while adjusting for covariates, including indigenous status. Results: After excluding cases not meeting the inclusion criteria, 34,128 Victoria women who had a history of PTD and 374,538 women who had deliveries at terms were analyzed. A history of PTD was shown to be associated with significantly increased risk of recurrent CVD, while adjusting for all covariates, including indigenous status, with an adjusted hazard ratio (aHR) of 1.70 (95% confidence interval [CI]: 1.54-1.86, p < 0.0001). Aboriginal and Torres Strait Islander women had substantially increased risk of experiencing recurrent CVD after birth over their lifetime (aHR: 3.22, 95% CI: 2.39-4.35, p < 0.0001). Conclusions: Recognizing PTD as a nontraditional risk factor of CVD may play a role in the formulation of care plans for primary and secondary CVD prevention in women with such a history.

First Trimester Prediction of Preterm Delivery in the Absence of Other Pregnancy-Related Complications Using Cardiovascular-Disease Associated MicroRNA Biomarkers

The aim of the study was to determine if aberrant expression profile of cardiovascular disease associated microRNAs would be able to predict within 10 to 13 weeks of gestation preterm delivery such as spontaneous preterm birth (PTB) or preterm prelabor rupture of membranes (PPROM) in the absence of other pregnancy-related complications (gestational hypertension, preeclampsia, fetal growth restriction, or small for gestational age). In addition, we assessed if aberrant expression profile of cardiovascular disease associated microRNAs would be able to predict preterm delivery before and after 34 weeks of gestation. The retrospective study was performed within the period November 2012 to March 2020. Whole peripheral blood samples were collected from 6440 Caucasian individuals involving 41 PTB and 65 PPROM singleton pregnancies. A control group, 80 singleton term pregnancies, was selected on the base of equal sample storage time. Gene expression of 29 selected cardiovascular disease associated microRNAs was studied using real-time RT-PCR. Downregulation of miR-16-5p, miR-20b-5p, miR-21-5p, miR-24-3p, miR-26a-5p, miR-92a-3p, miR-126-3p, miR-133a-3p, miR-145-5p, miR-146a-5p, miR-155-5p, miR-210-3p, miR-221-3p and miR-342-3p was observed in pregnancies with preterm delivery before 37 (≤36 + 6/7) weeks of gestation. Majority of downregulated microRNAs (miR-16-5p, miR-24-3p, miR-26a-5p, miR-92a-3p, miR-133a-3p, miR-145-5p, miR-146a-5p, miR-155-5p, miR-210-3p, and miR-342-3p) was associated with preterm delivery occurring before 37 (≤36 + 6/7) weeks of gestation. The only miR-210-3p was downregulated in pregnancies with preterm delivery before 34 (≤33 + 6/7) weeks of gestation. The type of preterm delivery also had impact on microRNA gene expression profile. Downregulation of miR-24-3p, miR-92a-3p, miR-155-5p, and miR-210-3p was a common feature of PTB and PPROM pregnancies. Downregulation of miR-16-5p, miR-20b-5p, miR-26a-5p, miR-126-3p, miR-133a-3p, miR-146a-5p, miR-221-3p, and miR-342-3p appeared just in PTB pregnancies. No microRNA was uniquely dysregulated in PPROM pregnancies. The combination of 12 microRNAs (miR-16-5p, miR-20b-5p, miR-21-5p, miR-24-3p, miR-26a-5p, miR-92a-3p, miR-133a-3p, miR-145-5p, miR-146a-5p, miR-155-5p, miR-210-3p, and miR-342-3p, AUC 0.818, p < 0.001, 74.53% sensitivity, 75.00% specificity, cut off > 0.634) equally as the combination of 6 microRNAs (miR-16-5p, miR-21-5p, miR-24-3p, miR-133a-3p, miR-155-5p, and miR-210-3p, AUC 0.812, p < 0.001, 70.75% sensitivity, 78.75% specificity, cut off > 0.652) can predict preterm delivery before 37 weeks of gestation in early stages of gestation in 52.83% pregnancies at 10.0% FPR. Cardiovascular disease associated microRNAs represent promising biomarkers with very good diagnostical potential to be implemented into the current routine first trimester screening programme to predict preterm delivery.

Adverse pregnancy outcomes are associated with an increased risk of postpartum prediabetes and diabetes in Chinese women with gestational diabetes

AIMS

To explore associations between adverse pregnancy outcomes and risk of postpartum diabetes and prediabetes among Chinese women with gestational diabetes mellitus (GDM).

METHODS

A total of 507 women with GDM who participated in a randomized controlled trial were successfully followed up at a median of 9.1  (interquartile range: 7.7-11.3) weeks after delivery and underwent a 75 g 2-h oral glucose tolerance test. GDM was diagnosed according to the International Association of Diabetes and Pregnancy Study Group's criteria. Postpartum diabetes and prediabetes were defined by the World Health Organization's. Generalized logit model was used to obtain odds ratios (OR) and 95% confidence interval (CI) of adverse pregnancy outcomes for postpartum diabetes, prediabetes and abnormal glucose regulation (AGR).

RESULTS

Of 507 women with GDM, 3.7% (19) women developed postpartum diabetes, 35.1% (178) women developed postpartum prediabetes. Preterm birth was associated with increased risk of postpartum prediabetes and AGR (adjusted OR: 3.24, 95%CI: 1.48-7.07 & 3.16, 1.46-6.85). Low birth weight was associated with the risk of postpartum prediabetes, diabetes and AGR (adjusted OR: 2.78, 95%CI: 1.13-6.86; 5.21, 1.13-24.02 & 2.99, 1.24-7.21).

CONCLUSIONS

Preterm birth and low birth weight were predictive of postpartum prediabetes, diabetes or AGR in Chinese women with GDM.

Preterm Delivery and Long-term Risk of Hypertension in Women

Importance

Preterm delivery has been associated with future cardiometabolic disorders in women. However, the long-term risks of chronic hypertension associated with preterm delivery and whether such risks are attributable to familial confounding are unclear. Such knowledge is needed to improve long-term risk assessment, clinical monitoring, and cardiovascular prevention strategies in women.

Objective

To examine the long-term risks of chronic hypertension associated with preterm delivery in a large population-based cohort of women.

Design, Setting, and Participants

This national cohort study assessed all 2 195 989 women in Sweden with a singleton delivery from January 1, 1973, to December 31, 2015. Data analyses were conducted from March 8, 2021, to August 20, 2021.

Exposures

Pregnancy duration identified from nationwide birth records.

Main Outcomes and Measures

New-onset chronic hypertension identified from primary care, specialty outpatient, and inpatient diagnoses using administrative data. Cox proportional hazards regression was used to compute hazard ratios (HRs) while adjusting for preeclampsia, other hypertensive disorders of pregnancy, and other maternal factors. Cosibling analyses were assessed for potential confounding by shared familial (genetic and/or environmental) factors.

Results

In 46.1 million person-years of follow-up, 351 189 of 2 195 989 women (16.0%) were diagnosed with hypertension (mean [SD] age, 55.4 [9.9] years). Within 10 years after delivery, the adjusted HR for hypertension associated with preterm delivery (gestational age <37 weeks) was 1.67 (95% CI, 1.61-1.74) and when further stratified was 2.23 (95% CI, 1.98-2.52) for extremely preterm (22-27 weeks of gestation), 1.85 (95% CI, 1.74-1.97) for moderately preterm (28-33 weeks of gestation), 1.55 (95% CI, 1.48-1.63) for late preterm (34-36 weeks of gestation), and 1.26 (95% CI, 1.22-1.30) for early-term (37-38 weeks of gestation) compared with full-term (39-41 weeks of gestation) delivery. These risks decreased but remained significantly elevated at 10 to 19 years (preterm vs full-term delivery: adjusted HR, 1.40; 95% CI, 1.36-1.44), 20 to 29 years (preterm vs full-term delivery: adjusted HR, 1.20; 95% CI, 1.18-1.23), and 30 to 43 years (preterm vs full-term delivery: adjusted HR, 95% CI, 1.12; 1.10-1.14) after delivery. These findings were not explained by shared determinants of preterm delivery and hypertension within families.

Conclusions and Relevance

In this large national cohort study, preterm delivery was associated with significantly higher future risks of chronic hypertension. These associations remained elevated at least 40 years later and were largely independent of other maternal and shared familial factors. Preterm delivery should be recognized as a lifelong risk factor for hypertension in women.

Pre-term delivery and long-term risk of heart failure in women: a national cohort and co-sibling study

AIMS

Women who deliver pre-term have higher future risks of hypertension and ischaemic heart disease, but long-term risks of heart failure (HF) are unknown. We examined these risks in a large national cohort.

METHODS AND RESULTS

All 2 201 284 women with a singleton delivery in Sweden during 1973-2015 were followed up for inpatient or outpatient HF diagnoses through 2015. Cox regression was used to compute hazard ratios (HRs) for HF associated with pregnancy duration, adjusting for other maternal factors. Co-sibling analyses assessed for confounding by shared familial (genetic and/or environmental) factors. In 48.2 million person-years of follow-up, 19 922 women were diagnosed with HF (median age: 60.7 years). Within 10 years after delivery, the adjusted HR was 2.96 [95% confidence interval (CI): 2.48-3.53] for HF associated with pre-term (gestational age: <37 weeks) compared with full-term (39-41 weeks) delivery. Stratified HRs were 4.27 (2.54-7.17) for extremely pre-term (22-27 weeks), 3.39 (2.57-4.48) for moderately pre-term (28-33 weeks), 2.70 (2.19-3.32) for late pre-term (34-36 weeks), and 1.70 (1.45-1.98) for early term (37-38 weeks). These HRs declined but remained elevated at 10-19 years (pre-term vs. full term: HR: 2.19; 95% CI: 1.94-2.46), 20-29 years (1.80; 1.67-1.95), and 30-43 years (1.56; 1.47-1.66) after delivery, and were not explained by shared familial factors.

CONCLUSION

Pre-term and early term delivery were associated with markedly increased future hazards for HF, which persisted after adjusting for other maternal and familial factors and remained elevated 40 years later. Pre-term and early-term delivery should be recognized as risk factors for HF across the life course.

KEY QUESTION

What are the long-term hazards for heart failure (HF) across the life course in women who deliver preterm?

KEY FINDING

Preterm and early term delivery were associated with ∼3- and 1.7-fold adjusted hazards for HF in the next 10 years vs. full-term delivery. These hazards declined but remained elevated 40 years later, and were not explained by shared familial factors.

TAKE HOME MESSAGE

Preterm and early term delivery were associated with increased future hazards for HF, which persisted for 40 years after adjusting for other maternal and familial factors. Preterm and early term delivery should be recognized as lifelong risk factors for HF.

Maternal LINE-1 DNA Methylation in Early Spontaneous Preterm Birth

Despite considerable effort aimed at decreasing the incidence of spontaneous preterm birth (SPTB), it remains the leading cause of infant mortality and morbidity. The aim of this study was to evaluate maternal LINE-1 DNA methylation (DNAm), along with DNMT polymorphisms and factors proposed to modulate DNAm, in patients who delivered early preterm. This case-control study included women who delivered spontaneously early preterm (23-33^6/7 weeks of gestation), and control women. DNAm was analyzed in peripheral blood lymphocytes by quantification of LINE-1 DNAm using the MethyLight method. There was no significant difference in LINE-1 DNAm between patients with early PTB and controls. Among the investigated predictors, only the history of previous PTB was significantly associated with LINE-1 DNAm in PTB patients (β = -0.407; R² = 0.131; p = 0.011). The regression analysis showed the effect of DNMT3B rs1569686 TT+TG genotypes on LINE-1 DNAm in patients with familial PTB (β = -0.524; R² = 0.275; p = 0.037). Our findings suggest novel associations of maternal LINE-1 DNA hypomethylation with DNMT3B rs1569686 T allele. These results also contribute to the understanding of a complex (epi)genetic and environmental relationship underlying the early PTB.

Contributions of Preterm Delivery to Cardiovascular Disease Risk Prediction in Women

Background: Preterm delivery is associated with a 1.4- to 2-fold increased risk of cardiovascular disease (CVD), but inclusion of preterm delivery in CVD risk prediction algorithms has not been tested. We evaluated whether including preterm delivery and parity in CVD risk scores improved identification of women at high risk versus scores based on traditional risk factors. Methods: We predicted 10-year CVD risk using 119,587 observations contributed by 76,512 women ≥40 years of age and 20-year CVD risk with 72,533 women ≥40 years of age and 72,872 women ≥30 years of age from the Nurses' Health Study II. Cox proportional hazards models were fit with established CVD risk factors (Model 1) and established risk factors plus preterm delivery and parity (Model 2). We evaluated model fit, calibration, discrimination, and risk reclassification. Results: Very preterm delivery (<32 weeks) was associated with CVD in all 10- and 20-year models that included the established CVD risk factors (e.g., hazard ratio: 1.61, 95% confidence interval: 1.19 to 2.20 in 10-year risk model). Model 2 had improved fit relative to Model 1, but discrimination was not improved in Model 2 based on the C-difference or net reclassification index. Similar models for 20-year CVD risk prediction at age ≥30 years indicated improved discrimination when including preterm delivery and parity. Conclusions: Incorporating preterm delivery and parity into CVD risk scores appears most useful when women are young, before they develop established CVD risk factors. Observed improvements in risk prediction were small and warrant further investigation to confirm our findings and assess utility in a clinical setting.

Preterm Delivery and Long-Term Risk of Stroke in Women: A National Cohort and Cosibling Study

BACKGROUND

Stroke has a high burden of disease in women, and adverse pregnancy outcomes have been identified as important risk factors for stroke later in life. However, long-term risks of stroke associated with preterm delivery and whether such risks are attributable to familial confounding are unclear. Such knowledge is needed to improve long-term risk assessment and stroke prevention in women.

METHODS

A national cohort study was conducted of all 2 188 043 women with a singleton delivery in Sweden in 1973 through 2015 who were followed up for stroke identified from nationwide diagnoses through 2015. Cox regression was used to compute adjusted hazard ratios (aHRs) for stroke associated with pregnancy duration, and cosibling analyses assessed for confounding by shared familial (genetic or environmental) factors.

RESULTS

In 48.0 million person-years of follow-up, 36 372 (1.7%) women were diagnosed with stroke. In the 10 years after delivery, the aHR for stroke associated with preterm delivery (gestational age <37 weeks) was 1.61 (95% CI, 1.45-1.79) and further stratified was 2.81 (95% CI, 2.02-3.91) for extremely preterm (22-27 weeks), 2.07 (95% CI, 1.74-2.46) for very preterm (28-33 weeks), 1.38 (95% CI, 1.21-1.57) for late preterm (34-36 weeks), and 1.15 (95% CI, 1.06-1.24) for early term (37-38 weeks), compared with full-term (39-41 weeks) delivery. These risks remained similarly elevated at 10 to 19 years after delivery (preterm versus full-term: aHR, 1.61 [95% CI, 1.50-1.74]) and then declined but remained significantly elevated at 20 to 29 years (aHR, 1.35 [95% CI, 1.28-1.44]) and 30 to 43 years (aHR, 1.35 [95% CI, 1.27-1.42]). Preterm delivery was associated with both hemorrhagic (aHR, 1.31 [95% CI, 1.25-1.38]) and ischemic (aHR, 1.54 [95% CI, 1.47-1.61]) stroke across the entire follow-up period (up to 43 years). These findings were not explained by shared determinants of preterm delivery and stroke within families. Stroke risks were higher after either spontaneous or medically indicated preterm delivery, and recurrent preterm delivery was associated with further increases in risk.

CONCLUSIONS

In this large national cohort, preterm delivery was associated with higher future risks of both hemorrhagic and ischemic stroke. These associations remained substantially elevated at least 40 years later, and were largely independent of covariates and shared familial factors. Preterm delivery should be recognized as a risk factor for stroke in women across the life course.

A History of Preterm Delivery Is Associated with Aberrant Postpartal MicroRNA Expression Profiles in Mothers with an Absence of Other Pregnancy-Related Complications

This prospective cross-sectional case-control study investigated the postpartal gene expression of microRNAs associated with diabetes/cardiovascular/cerebrovascular diseases in the peripheral white blood cells of women with anamnesis of preterm prelabor rupture of membranes (n = 58), spontaneous preterm birth (n = 55), and term delivery (n = 89) by a quantitative reverse transcription polymerase chain reaction. After pregnancies complicated by preterm prelabor rupture of membranes or spontaneous preterm birth, mothers showed diverse expression profiles for 25 out of 29 tested microRNAs (miR-1-3p, miR-16-5p, miR-17-5p, miR-20a-5p, miR-20b-5p, miR-21-5p, miR-23a-3p, miR-24-3p, miR-26a-5p, miR-29a-3p, miR-100-5p, miR-103a-3p, miR-125b-5p, miR-126-3p, miR-130b-3p, miR-133a-3p, miR-143-3p, miR-145-5p, miR-146a-5p, miR-181a-5p, miR-195-5p, miR-199a-5p, miR-221-3p, miR-499a-5p, and miR-574-3p). The earliest gestational ages at delivery and the lowest birth weights of newborns were associated with the highest postpartal levels of the previously mentioned microRNAs in maternal peripheral white blood cells. Administration of tocolytic drugs in order to prolong pregnancy, used in order to administer and complete a full course of antenatal corticosteroids, was associated with alterations in postpartal microRNA expression profiles to a lesser extent than in women with imminent delivery, where there was insufficient time for administration of tocolytics and antenatal corticosteroids. Overall, mothers who did not receive tocolytic therapy (miR-24-3p and miR-146a-5p) and mothers who did not receive corticosteroid therapy (miR-1-3p, miR-100-5p, and miR-143-3p) had increased or showed a trend toward increased postpartal microRNA expression when compared with mothers given tocolytic and corticosteroid therapy. In addition, mothers with serum C-reactive protein levels above 20 mg/L, who experienced preterm labour, showed a trend toward increased postpartal expression profiles of miR-143-3p and miR-199a-5p when compared with mothers with normal serum C-reactive protein levels. On the other hand, the occurrence of maternal leukocytosis, the presence of intra-amniotic inflammation (higher levels of interleukin 6 in the amniotic fluid), and the administration of antibiotics at the time of preterm delivery had no impact on postpartal microRNA expression profiles in mothers with a history of preterm delivery. Likewise, the condition of the newborns at the moment of birth, determined by Apgar scores at 5 and 10 min and the pH of cord arterial blood, had no influence on the postpartal expression profiles of mothers with a history of preterm delivery. These findings may contribute to explaining the increased cardiovascular risk in mothers with anamnesis of preterm delivery, and the greater increase of maternal cardiovascular risk with the decrease of gestational age at delivery. Women with preterm delivery in their anamnesis represent a high-risk group with special needs on a long-term basis, with a need to apply preventive and therapeutic interventions as early as possible.

Cardiovascular Disease-Related Morbidity and Mortality in Women With a History of Pregnancy Complications

BACKGROUND

Women with a history of certain pregnancy complications are at higher risk for cardiovascular (CVD) disease. However, most clinical guidelines only recommend postpartum follow-up of those with a history of preeclampsia, gestational diabetes mellitus, or preterm birth. This systematic review was undertaken to determine if there is an association between a broader array of pregnancy complications and the future risk of CVD.

METHODS

We systematically searched PubMed, MEDLINE and EMBASE (via Ovid), CINAHL, and the Cochrane Library from inception to September 22, 2017, for observational studies of the association between the hypertensive disorders of pregnancy, placental abruption, preterm birth, gestational diabetes mellitus, low birth weight, small-for-gestational-age birth, stillbirth, and miscarriage and subsequent CVD. Likelihood ratio meta-analyses were performed to generate pooled odds ratios (OR) and 95% intrinsic confidence intervals (ICI).

RESULTS

Our systematic review included 84 studies (28 993 438 patients). Sample sizes varied from 250 to 2 000 000, with a median follow-up of 7.5 years postpartum. The risk of CVD was highest in women with gestational hypertension (OR 1.7; 95% ICI, 1.3-2.2), preeclampsia (OR 2.7; 95% ICI, 2.5-3.0), placental abruption (OR 1.8; 95% ICI, 1.4-2.3), preterm birth (OR 1.6; 95% ICI, 1.4-1.9), gestational diabetes mellitus (OR 1.7; 95% ICI, 1.1-2.5), and stillbirth (OR 1.5; 95% ICI, 1.1-2.1). A consistent trend was seen for low birth weight and small-for-gestational-age birth weight but not for miscarriage.

CONCLUSIONS

Women with a broader array of pregnancy complications, including placental abruption and stillbirth, are at increased risk of future CVD. The findings support the need for assessment and risk factor management beyond the postpartum period.

Effect of premature birth on long-term systolic blood pressure variability in women

Objective:

To investigate the effect of premature birth (PTB) on long-term systolic blood pressure (SBP) variability (SBPV) in women.

Methods:

A total of 1974 pregnant women were divided into PTB group and non-PTB (NPTB) group. The SBP standard deviation (SSD) was calculated by four annual SBP values measured in 2006–2007, 2008–2009, 2010–2011, and 2012–2013. SBP coefficient of variation (SCV) was calculated by dividing SSD with mean SBP. Multivariate logistic regression analysis was used to analyze the influence of PTB on long-time SSD and SCV in women.

Results:

SSD and SCV of the PTB group (10.95 mm Hg and 9.05%, respectively) were higher than those of the NPTB group (9.81 mm Hg and 8.23%, respectively), but there were no significant differences (p>0.05). The number of patients with SSD >9.87 mm Hg and SCV >8.28% in the PTB and NPTB groups was 57 (51.40%) and 62 (55.90%) and 747 (40.10%) and 841 (45.10%), respectively. The number of patients with SSD >9.87 mm Hg and SCV >8.28% in the PTB group was significantly higher than that in the NPTB group (p<0.05). Multiple logistic regression analysis showed that after adjusting other risk factors, the PTB group was at a risk of SSD and SCV elevations with OR values of 1.60 (95% CI: 1.06–2.40) and 1.64 (95% CI: 1.10–2.45), respectively.

Conclusion:

PTB is a risk factor of long-time SBPV in women, which might be a potential reason for cardiovascular events. Pregnancy may be an important opportunity for early identification of women at an increased risk of cardiovascular disease later in life.

Preterm Delivery and Maternal Cardiovascular Disease Risk Factors: The Nurses' Health Study II

Background: Preterm delivery has been linked to future maternal cardiovascular disease (CVD); however, research investigating clinical CVD risk factors is limited. We evaluated whether women who have delivered an infant preterm are at higher risk of developing CVD risk factors after adjustment for prepregnancy confounders. Materials and Methods: We examined the association between preterm delivery and incident chronic hypertension, type 2 diabetes mellitus (T2DM), and hypercholesterolemia among 57,904 parous women in the Nurses' Health Study II. Multivariable Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations between preterm delivery in first pregnancy and each CVD risk factor; adjusted cumulative incidence curves were computed using the Breslow estimator. Results: Preterm delivery (<37 weeks) was associated with HRs of 1.11 (95% CI: 1.06-1.17) for chronic hypertension, 1.17 (95% CI: 1.03-1.33) for T2DM, and 1.07 (95% CI: 1.03-1.11) for hypercholesterolemia, adjusting for age, race/ethnicity, parental education, and prepregnancy confounders (e.g., body mass index, smoking, and family history). HRs were higher in women who delivered very preterm (<32 weeks) and in the first 10 years after first birth. The cumulative incidence of each risk factor was highest in women who delivered very preterm. Conclusions: Women with a history of preterm delivery are at higher risk of developing chronic hypertension, T2DM, and hypercholesterolemia in the years after pregnancy. This increased risk was particularly pronounced in the first 10 years after a preterm delivery, indicating that it may be an important time period to implement lifestyle interventions.

Cardiovascular biomarkers in the years following pregnancies complicated by hypertensive disorders or delivered preterm

BACKGROUND

Women with a history of hypertensive disorders of pregnancy and preterm delivery have an increased risk of cardiovascular disease (CVD). Chronic inflammation, endothelial dysfunction, and dyslipidemia may link pregnancy outcomes with CVD.

OBJECTIVE

We evaluated whether women with a history of HDP or normotensive preterm delivery had adverse CVD biomarker profiles after pregnancy.

STUDY DESIGN

We identified parous women from the Nurses' Health Study II with C-reactive protein (CRP; n = 2614), interleukin-6 (IL-6; n = 2490), glycated hemoglobin (n = 885), intracellular adhesion molecule-1 (n = 1231), high density lipoprotein cholesterol (n = 931), low density lipoprotein cholesterol (n = 931), triglycerides (n = 1428), or total cholesterol (n = 2940) assessed in stored blood samples. Multivariable-adjusted robust linear regression models evaluated percent differences and 95% confidence intervals (CIs) in each biomarker associated with a history of HDP or preterm delivery.

RESULTS

Ten percent of women had a history of HDP, while 11% with normotensive pregnancies had at least one preterm delivery. Median time from first pregnancy to blood draw was 17 years (interquartile range: 12, 22). Plasma levels of CRP and IL-6 were 34.4% (95% CI: 17.2, 54.1), and 11.6% higher (95% CI: 2.1, 21.9) respectively, among women with a history of HDP compared to those with only normotensive pregnancies. Altered CVD biomarker levels were otherwise not present in women with a history of HDP or preterm delivery.

CONCLUSION

CRP and IL-6, but not other CVD biomarkers, were elevated in women with a history of HDP in the years following pregnancy, suggesting inflammation may be a pathway linking HDP with future CVD risk.

Association of Spontaneous Preterm Delivery and Future Maternal Cardiovascular Disease

Cardiovascular disease (CVD) risk factors are well established. However, little is known about a woman's cardiovascular response to pregnancy, which appears to be an early marker of future maternal CVD risk. Spontaneous preterm delivery (sPTD) has been associated with a ≤3-fold increased risk of maternal CVD death later in life compared with having a term delivery. This review focuses on 3 key areas to critically assess the association of sPTD and future maternal CVD risk: (1) CVD risk factors, (2) inflammatory biomarkers of interest, and (3) specific forms of vascular dysfunction, such as endothelial function and arterial stiffness, and mechanisms by which each may be linked to sPTD. The association of sPTD with subsequent future maternal CVD risk suggests that a woman's abnormal response to pregnancy may serve as her first physiological stress test. These findings suggest that future research is needed to understand why women with sPTD may be at risk for CVD to implement effective interventions earlier in a woman's life.

Cardiovascular biochemical risk factors among women with spontaneous preterm delivery

OBJECTIVE

To determine whether women delivering preterm have unfavorable cardiovascular profiles as compared with women who deliver at term.

METHODS

A prospective observational cohort study enrolled 165 women with spontaneous preterm delivery (sPTD) at 24⁺⁰ and 36⁺⁶ gestational weeks in three perinatal care centers in The Netherlands between August 2012 and August 2014. Total cholesterol, triglycerides, high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol, apolipoprotein, glucose, and homocysteine were measured within 24 hours after delivery. Lipids and cardiovascular biochemical risk factors were compared between women with sPTD and an external comparison group of 30 women with term delivery via analysis of covariance.

RESULTS

Mean gestational age at delivery was 30.7 ± 3.6 weeks in the sPTD group and 40.3 ± 1.3 weeks in the reference group. Data were adjusted for body mass index, age, and center. As compared with the reference group, total cholesterol and LDL-cholesterol levels were lower and glucose levels were higher among women with sPTD.

CONCLUSION

An association between sPTD and unfavorable lipids and cardiovascular biochemical risk factors was not established. The higher levels of glucose in the sPTD group might be due to increased insulin resistance, which is associated with a higher risk of sPTD.

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 Delivery and Maternal Cardiovascular Disease in Young and Middle-Aged Adult Women

BACKGROUND

Preterm delivery has been shown to be associated with increased risk of cardiovascular disease (CVD), but it is unknown whether this risk remains after adjustment for prepregnancy lifestyle and CVD risk factors.

METHODS

We examined the association between history of having delivered an infant preterm (<37 weeks) and CVD in 70 182 parous women in the Nurses' Health Study II. Multivariable Cox proportional-hazards models were used to estimate hazards ratios (HRs) and 95% confidence intervals (CIs) for CVD events (myocardial infarction and stroke, n=949); we also adjusted for intermediates to determine the proportion of the association between preterm and CVD accounted for by postpartum development of CVD risk factors.

RESULTS

After adjusting for age, race, parental education, and prepregnancy lifestyle and CVD risk factors, preterm delivery in the first pregnancy was associated with an increased risk of CVD (HR, 1.42; 95% CI, 1.16-1.72) in comparison with women with a term delivery (≥37 weeks) in the first pregnancy. When preterm delivery was split into moderate preterm (≥32 to <37 weeks) and very preterm (<32 weeks), the HRs were 1.22 (95% CI, 0.96-1.54) and 2.01 (95% CI, 1.47-2.75), respectively. The increased rate of CVD in the very preterm group persisted even among women whose first pregnancy was not complicated by hypertensive disorders of pregnancy (HR, 2.01; 95% CI, 1.38-2.93). In comparison with women with at least 2 pregnancies, all of which were delivered at term, women with a preterm first birth and at least 1 later preterm birth had a HR of CVD of 1.65 (95% CI, 1.20-2.28). The association between moderate preterm first birth and CVD was accounted for in part by the development of postpartum chronic hypertension, hypercholesterolemia, type 2 diabetes mellitus, and changes in body mass index (proportion accounted for, 14.5%; 95% CI, 4.0-41.1), as was the very-preterm-CVD relationship (13.1%; 95% CI, 9.0-18.7).

CONCLUSIONS

Preterm delivery is independently predictive of CVD and may be useful for CVD prevention efforts. Because only a modest proportion of the preterm-CVD association was accounted for by development of conventional CVD risk factors, further research may identify additional pathways.

Preterm delivery and elevated maternal total vascular resistance: signs of suboptimal cardiovascular adaptation to pregnancy?

OBJECTIVE

To evaluate the maternal hemodynamic profile in women with a diagnosis of threatened preterm delivery (TPD) in order to understand the possible pathophysiologic mechanism leading to an increased lifetime risk for future cardiovascular disease.

METHODS

Patients with a diagnosis of TPD were enrolled and assessed using a non-invasive method (USCOM^® ) for the determination of hemodynamic parameters. Vaginal and rectal swabs were taken, cervical length, blood inflammatory indices, fetal blood-vessel Doppler velocimetry were measured and gestational age at the time of delivery and neonatal outcomes were noted.

RESULTS

A total of 68 patients were enrolled and included in the analysis. The population was divided into two groups according to total vascular resistance (TVR): Group A with a TVR of ≤ 1000 dynes × s/cm⁵ (n = 48) and Group B with a TVR of > 1000 dynes × s/cm⁵ (n = 20). C-reactive protein (CRP) was higher in Group B than in Group A, suggesting a systemic inflammation status. Group B delivered earlier (32 + 4 weeks vs 38 + 2 weeks; P < 0.01) and neonatal outcome was worse than in Group A. Significantly lower values of cardiac output, stroke volume, peak velocity of flow, velocity time integral, minute distance, stroke volume index, cardiac index, stroke work, cardiac power, inotropy index and potential-to-kinetic energy ratio were observed in Group B than in Group A.

CONCLUSIONS

Women with a diagnosis of TPD showing TVR values of > 1000 dynes × s/cm⁵ and elevated levels of CRP are at high risk of preterm delivery. An impaired maternal cardiovascular adaptation during pregnancy in these patients might suggest a possible higher risk for subsequent future cardiovascular disease. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Preterm Delivery and Metabolic Syndrome in Women Followed From Prepregnancy Through 25 Years Later

OBJECTIVE

To investigate whether women who deliver preterm have excess risk for metabolic dysregulation independent of prepregnancy factors.

METHODS

We conducted a multicenter, longitudinal, observational study of 1,205 women (50% black) in the Coronary Artery Risk Development in Young Adults study with at least one birth between baseline (1985-1986) and year 25 and no metabolic syndrome or diabetes before pregnancy. Cardiometabolic factors were measured prepregnancy and at up to five subsequent examinations. We estimated the relative hazards of incident metabolic syndrome in women with one or more preterm births (less than 37 weeks of gestation, n=295) compared with only term births (37 weeks of gestation or greater, n=910). Self-reported gestational diabetes mellitus, hypertension during pregnancy, and time-dependent weight gain were also considered as covariates.

RESULTS

Of 315 cases of metabolic syndrome in 17,717 person-years of follow-up, the incidence rate was higher among women with preterm compared with term births (22.0 compared with 16.4 per 1,000 person-years; relative hazard 2.91 [95% confidence interval (CI) 2.75-3.09]). After adjustment for prepregnancy cardiometabolic factors and covariates, the relative hazard (95% CI) for metabolic syndrome was 1.52 (1.22-1.88) for women with preterm compared with term births. Gestational diabetes mellitus, hypertension during pregnancy, and weight gain only modestly attenuated this association. Elevated blood pressure (36.3% compared with 26.7%, P=.002) and central adiposity (51.5% compared with 44.0%, P=.02) were the individual metabolic syndrome components that were different in women with preterm compared with term births.

CONCLUSION

Women with a history of preterm birth have increased risk of incident metabolic syndrome compared with those with term births, independent of the prepregnancy metabolic status and pregnancy complications.

Epigenetic Biomarkers of Preterm Birth and Its Risk Factors

A biomarker is a biological measure predictive of a normal or pathogenic process or response. Biomarkers are often useful for making clinical decisions and determining treatment course. One area where such biomarkers would be particularly useful is in identifying women at risk for preterm delivery and related pregnancy complications. Neonates born preterm have significant morbidity and mortality, both in the perinatal period and throughout the life course, and identifying women at risk of delivering preterm may allow for targeted interventions to prevent or delay preterm birth (PTB). In addition to identifying those at increased risk for preterm birth, biomarkers may be able to distinguish neonates at particular risk for future complications due to modifiable environmental factors, such as maternal smoking or alcohol use during pregnancy. Currently, there are no such biomarkers available, though candidate gene and epigenome-wide association studies have identified DNA methylation differences associated with PTB, its risk factors and its long-term outcomes. Further biomarker development is crucial to reducing the health burden associated with adverse intrauterine conditions and preterm birth, and the results of recent DNA methylation studies may advance that goal.

Insights into genetic susceptibility in the etiology of spontaneous preterm birth

Preterm birth (PTB; <37 weeks of gestation) is a complex disorder, whose etiology is influenced by a variety of factors. A greater understanding of the biological mechanisms that contribute to PTB will facilitate identification of those at increased risk and may inform new treatments. To accomplish this, it is vital to elucidate the heritability patterns of this condition as well as the environment and lifestyle factors that increase risk for PTB. Identifying individual genes that contribute to the etiology of PTB presents particular challenges, and there has been little agreement among candidate gene and genome-wide studies performed to date. In this review we will evaluate recent genetic studies of spontaneous PTB, discuss common themes among their findings, and suggest approaches for future studies of PTB.

Duration of pregnancy, even at term, predicts long-term risk of coronary heart disease and stroke mortality in women: a population-based study

OBJECTIVE

Preterm delivery may predict an increased risk of cardiovascular disease in mothers, providing opportunities for prevention. No study had examined whether gestation length within the term period predicts future CVD, and there are few data segregating spontaneous from medically indicated deliveries.

STUDY DESIGN

We used proportional hazards models to predict CVD death by gestation length, adjusted for age, education, and delivery year among 688,662 women with births from 1967 through 1998 in the Medical Birth Registry of Norway. Mothers were traced in the National Cause of Death Registry through 2009; there were 2324 CVD deaths.

RESULTS

Compared with women who delivered spontaneously at 39-41 weeks' gestation, women who spontaneously delivered earlier had higher risks of CVD death. Hazard ratios were 1.9 at 22-31 weeks, 2.2 at 32-34 weeks, 1.6 at 35-36 weeks, and 1.4 at 37-38 weeks. Risks were higher among women with medically indicated deliveries (hazard ratio, 4.8 at 22-31 weeks, 2.7 at 32-34 weeks, 4.3 at 35-36 weeks, and 1.6 at 37-38 weeks compared with spontaneous deliveries at 39-41 weeks). Neither spontaneous nor indicated delivery after 41 weeks was associated with CVD mortality. Risks were highest with recurrent preterm pregnancies, and for women who delivered only one child, especially if that delivery was preterm.

CONCLUSION

Women who deliver spontaneously before 37 weeks had a 2-fold increased risk of CVD mortality compared with women who had delivered after 38 weeks. Even women with spontaneous deliveries at early term (37-38 weeks) had a 41% elevated risk of CVD death compared with women delivering at 39-41 weeks.

Adverse Pregnancy Conditions, Infertility, and Future Cardiovascular Risk: Implications for Mother and Child

Adverse pregnancy conditions in women are common and have been associated with adverse cardiovascular and metabolic outcomes such as myocardial infarction and stroke. As risk stratification in women is often suboptimal, recognition of non-traditional risk factors such as hypertensive disorders of pregnancy and premature delivery has become increasingly important. Additionally, such conditions may also increase the risk of cardiovascular disease in the children of afflicted women. In this review, we aim to highlight these conditions, along with infertility, and the association between such conditions and various cardiovascular outcomes and related maternal risk along with potential translation of risk to offspring. We will also discuss proposed mechanisms driving these associations as well as potential opportunities for screening and risk modification.

Preterm birth and future risk of maternal cardiovascular disease - is the association independent of smoking during pregnancy?

BACKGROUND

While the association of preterm birth and the risk of maternal cardiovascular disease (CVD) has been well-documented, most studies were limited by the inability to account for smoking during pregnancy - an important risk factor for both preterm birth and CVD. This study aimed to determine whether the increased future risk of maternal cardiovascular disease (CVD) associated with preterm birth is independent of maternal smoking during pregnancy.

METHODS

A population-based record linkage study of 797,056 women who delivered a singleton infant between 1994 and 2011 in New South Wales, Australia was conducted. Birth records were linked to the mothers' subsequent hospitaliation or death from CVD. Preterm births were categorised as late (35-36 weeks), moderate (33-34 weeks), or extreme (≤32 weeks); and as spontaneous or indicated. Cox proportional hazard regression was used to estimate adjusted hazard ratios (AHR) [95 % CI].

RESULTS

During the study period, 59,563 women (7.5 %) had at least one preterm birth. After adjustment for CVD risk factors other than smoking, AHR [95 % CI] of CVD among women who ever had a preterm birth was 1.78 [1.61-1.96]. Associations were greater for extreme (AHR = 1.98 [1.63-2.42]) and moderate (AHR = 2.06 [1.69-2.51]) than late preterm birth (AHR = 1.63 [1.44-1.85]), for indicated (AHR = 2.04 [1.75-2.38]) than spontaneous preterm birth (AHR = 1.65 [1.47-1.86]), and for having ≥ two (AHR = 2.29[1.75-2.99]) than having one preterm birth (AHR = 1.73[1.57-1.92]). A further adjustment for maternal smoking attenuated, but did not eliminate, the associations. Smoking during pregnancy was also independently associated with maternal CVD risks, with associations being stronger for mothers who smoked during last pregnancy (AHR = 2.07 [1.93-2.23]) than mothers who smoked during a prior pregnancy (AHR = 1.64 [1.41-1.90]).

CONCLUSIONS

Associations of preterm birth and maternal CVD risk are independent of maternal smoking during pregnancy. This underscores the importance of smoking cessation in reducing CVD and suggests that a history of preterm delivery (especially if severe, indicated or recurrent) identifies women who could be targeted for CVD screening and preventative therapies.

DNA methylation provides insight into intergenerational risk for preterm birth in African Americans

African Americans are at increased risk for spontaneous preterm birth (PTB). Though PTB is heritable, genetic studies have not identified variants that account for its intergenerational risk, prompting the hypothesis that epigenetic factors may also contribute. The objective of this study was to evaluate DNA methylation from maternal leukocytes to identify patterns specific to PTB and its intergenerational risk. DNA from peripheral leukocytes from African American women that delivered preterm (24-34 weeks; N = 16) or at term (39-41 weeks; N = 24) was assessed for DNA methylation using the HumanMethylation450 BeadChip. In maternal samples, 17,829 CpG sites associated with PTB, but no CpG site remained associated after correction for multiple comparisons. Examination of paired maternal-fetal samples identified 5,171 CpG sites in which methylation of maternal samples correlated with methylation of her respective fetus (FDR < 0.05). These correlated sites were enriched for association with PTB in maternal leukocytes. The majority of correlated CpG sites could be attributed to one or more genetic variants. They were also significantly more likely to be in genes involved in metabolic, cardiovascular, and immune pathways, suggesting a role for genetic and environmental contributions to PTB risk and chronic disease. The results of this study may provide insight into the factors underlying intergenerational risk for PTB and its consequences.

Other adverse pregnancy outcomes and future chronic disease

Cardiovascular disease is the leading cause of morbidity and mortality in females worldwide. Pregnancy is associated with significant physiologic changes that may function as a natural stress test to detect women at future risk. It is established that women who have had a pregnancy complicated by gestational diabetes or a hypertensive disorder of pregnancy are at increased risk of cardiovascular disease later in life, and there is growing evidence that women who deliver infants preterm or growth-restricted infants have an elevated risk as well. Consideration should be given to including these outcomes as indicators of cardiovascular risk. Pregnancy represents a teachable moment when it would be ideal to identify women at risk. Improved integration of women's primary health care and an enhanced knowledge base on the part of clinicians will be necessary to fully incorporate these findings into the clinical care of women.

Cardiovascular disease risk in women with a history of spontaneous preterm delivery: A systematic review and meta-analysis

BACKGROUND

Increasing evidence suggests a relation between having had spontaneous preterm delivery and cardiovascular disease in the future. We performed a systematic review and meta-analysis to assess the relation between a history of spontaneous preterm delivery and risk of ischaemic heart disease (IHD), stroke or overall cardiovascular disease (CVD).

METHODS

We carried out a systematic search in Medline (from 1966 to 17 July 2014) and Embase (from 1980 to 17 July 2014). We included studies with a cohort design assessing the relation between spontaneous preterm delivery and fatal or nonfatal IHD, stroke, or overall CVD. IHD, stroke and CVD were assessed through linkage with national registries. Hazard ratios (HRs) were pooled using a random-effects model.

RESULTS

Of the 10 cohort studies included; sample sizes ranged from 3706 to 923,686 women and follow-up ranged from 12-35 years. Spontaneous preterm delivery was related to an increased risk of developing or dying from IHD (HR 1.38, 95% confidence interval (CI) 1.22-1.57), stroke (HR 1.71, 95% CI 1.53-1.91) and overall CVD (relative risk (HR) 2.01, 95% CI 1.52-2.65). All studies found a positive effect, although substantial between-study heterogeneity was found for IHD and CVD.

CONCLUSION

Spontaneous preterm delivery is an independent risk factor for the development of IHD, stroke and overall CVD.

Sex differences in cardiovascular risk factors and disease prevention

Cardiovascular disease (CVD) has been seen as a men's disease for decades, however it is more common in women than in men. It is generally assumed in medicine that the effects of the major risk factors (RF) on CVD outcomes are the same in women as in men. Recent evidence has emerged that recognizes new, potentially independent, CVD RF exclusive to women. In particular, common disorders of pregnancy, such as gestational hypertension and diabetes, as well as frequently occurring endocrine disorders in women of reproductive age (e.g. polycystic ovary syndrome (PCOS) and early menopause) are associated with accelerated development of CVD and impaired CVD-free survival. With the recent availability of prospective studies comprising men and women, the equivalency of major RF prevalence and effects on CVD between men and women can be examined. Furthermore, female-specific RFs might be identified enabling early detection of apparently healthy women with a high lifetime risk of CVD. Therefore, we examined the available literature regarding the prevalence and effects of the traditional major RFs for CVD in men and women. This included large prospective cohort studies, cross-sectional studies and registries, as randomised trials are lacking. Furthermore, a literature search was performed to examine the impact of female-specific RFs on the traditional RFs and the occurrence of CVD. We found that the effects of elevated blood pressure, overweight and obesity, and elevated cholesterol on CVD outcomes are largely similar between women and men, however prolonged smoking is significantly more hazardous for women than for men. With respect to female-specific RF only associations (and no absolute risk data) could be found between preeclampsia, gestational diabetes and menopause onset with the occurrence of CVD. This review shows that CVD is the main cause of death in men and women, however the prevalence is higher in women. Determination of the CV risk profile should take into account that there are differences in impact of major CV RF leading to a worse outcome in women. Lifestyle interventions and awareness in women needs more consideration. Furthermore, there is accumulating evidence that female-specific RF are of influence on the impact of major RF and on the onset of CVD. Attention for female specific RF may enable early detection and intervention in apparently healthy women. Studies are needed on how to implement the added RF's in current risk assessment and management strategies to maximize benefit and cost-effectiveness specific in women.

Placental Nkx2-5 and target gene expression in early-onset and severe preeclampsia

OBJECTIVE

Preeclampsia (PE) affects 2-8% of pregnancies worldwide and is a significant source of maternal and neonatal morbidity and mortality. However, the mechanisms underlying PE are poorly understood and major questions regarding etiology and risk factors remain to be addressed. Our objective was to examine whether abnormal expression of the cardiovascular developmental transcription factor, Nkx2-5, was associated with early onset and severe preeclampsia (EOSPE).

METHODS

Using qPCR and immunohistochemical assay, we examined expression of Nkx2-5 and target gene expression in EOSPE and control placental tissue. We tested resulting mechanistic hypotheses in cultured cells using shRNA knockdown, qPCR, and western blot.

RESULTS

Nkx2-5 is highly expressed in racially disparate fashion (Caucasians > African Americans) in a subset of early EOSPE placentae. Nkx2-5 mRNA expression is highly correlated (Caucasians > African Americans) to mRNA expression of the preeclampsia marker sFlt-1, and of the Nkx2-5 target and RNA splicing factor, Sam68. Knockdown of Sam68 expression in cultured cells significantly impacts sFlt-1 mRNA isoform generation in vitro, supporting a mechanistic hypothesis that Nkx2-5 impacts EOSPE severity in a subset of patients via upregulation of Sam68 to increase sFlt-1 expression. Expression of additional Nkx2-5 targets potentially regulating metabolic stress response is also elevated in a racially disparate fashion in EOSPE.

CONCLUSIONS

Expression of Nkx2-5 and its target genes may directly influence the genesis and racially disparate severity, and define a mechanistically distinct subclass of EOSPE.

Preterm birth and subsequent risk of type 2 diabetes in black women

BACKGROUND

Gestational diabetes is a precursor to type 2 diabetes. Little is known about the relation of other common pregnancy complications, such as preterm birth, to risk of type 2 diabetes.

METHODS

We assessed preterm birth in relation to incident type 2 diabetes among 31,101 participants from the Black Women's Health Study. Preterm birth, defined as <37 weeks gestation, was reported at baseline (1995) and on subsequent biennial follow-up questionnaires. Self-reported type 2 diabetes diagnoses were ascertained on biennial questionnaires through 2009. We used Cox proportional hazards models to calculate incidence rate ratios (IRRs) and 95% confidence intervals (CIs), adjusting for potential confounders.

RESULTS

At baseline, 5162 participants (19%) reported a history of giving birth preterm, of which 16% occurred at <32 weeks gestation. A total of 3261 cases of type 2 diabetes were ascertained during follow-up. Ever having had a preterm birth was associated with a 20% increased risk (95% CI = 1.11-1.31) after adjusting for age at first birth, family history of diabetes, education, respondent having been born preterm, and body mass index. Gestational age <32 weeks was associated with the greatest risk (IRR = 1.27 [95% CI = 1.06-1.51]). Among women without a history of gestational diabetes, the IRR for type 2 diabetes among women who ever had a preterm birth was 1.17 (1.07-1.28).

CONCLUSION

Preterm birth was associated with an increased type 2 diabetes risk in black mothers, independent of gestational diabetes.