Vasculopathic and thrombophilic risk factors for spontaneous preterm birth

Abnormal maternal apolipoprotein levels during pregnancy are risk factors for preterm birth in women with dichorionic twin pregnancies: A retrospective study

OBJECTIVE

In singleton-pregnant women, abnormal maternal apolipoprotein levels have been confirmed as a risk factor for preterm birth. However, there are currently no studies on the relationship of the related research in twin-pregnant women.

METHODS

This single-center retrospective study included 743 dichorionic twin-pregnant women who delivered between January 2019 and December 2020. Twins delivered before 37 weeks gestation were categorized as the preterm group, while those delivered at or after 37 weeks gestation were classified as the term group. Maternal serum apolipoprotein A1 (ApoA1) levels, apolipoprotein B (ApoB) levels, and the ApoB/ApoA1 ratio were measured in the first trimester(6-14 weeks), the second trimester(18-28 weeks) and the third trimester(after 28 weeks). We conducted SPSS analysis to evaluate the correlation between ApoA1 levels, ApoB levels, the ApoB/ApoA1 ratio and preterm birth.

RESULTS

Among the 743 included dichorionic twin-pregnant women, 53.57 % (398/743) delivered preterm. Compared with the term group, the ApoA1 levels in the third trimester were lower (p < 0.001), while the Apo B/ApoA1 ratio was higher in the second (p = 0.01) and third trimesters in the preterm group (p = 0.001). When preterm birth was categorized as iatrogenic and spontaneous preterm birth, the results were similar. In the analysis stratified by prepregnancy BMI, a higher risk of preterm birth was associated with low ApoA1 levels and a high Apo B/ApoA1 ratio in the second and third trimesters only among the subgroup of overweight/obese dichorionic twin-pregnant women.

CONCLUSIONS

Low ApoA1 levels and a high Apo B/ApoA1 ratio during the second and third trimesters were associated with a high incidence of preterm birth for overweight/obese dichorionic twin-pregnant women.

Gene expression of cardiovascular risk markers in mononuclear cells of pregnant woman in relation to plasma leptin and homocysteine levels: A cross sectional study

OBJECTIVE

To investigate the relationship between anthropometric, biochemical, and hematologic parameters and serum leptin and homocysteine (Hcy) levels. Also, to determine the effect of leptin and Hcy on expression of genes associated with cardiovascular disease susceptibility (APOA1, LRP1, COX-1, and COX-2) in mononuclear cells of healthy pregnant women.

METHODS

Between August 2018 and January 2020, a cross-sectional study was conducted on 161 healthy pregnant women in Tabasco, southeastern Mexico. The study population was classified by trimester, according to gestational pregnancy. Anthropometric, biochemical (leptin and homocysteine), and hematologic data were obtained under fasting conditions. APOA1, LRP1, COX-1, and COX-2 expression in mononuclear cells was evaluated using RT-qPCR.

RESULTS

Red cell indices (hemoglobin, hematocrit, and erythrocytes) were negatively and positively correlated with leptin and Hcy levels, respectively, in the first- and second-trimester groups. Increased leptin levels and low red cell indices were significantly associated with BMI <25.0 in the second-trimester group; however, no significant differences were observed in Hcy levels. Increased leptin and Hcy levels were significantly associated with high lipid indicators in the first- and third-trimester groups, respectively. High APOA1 and COX-2 expression was significantly associated with reduced leptin and increased Hcy levels in the second- and third-trimester groups.

CONCLUSION

Increased leptin and Hcy levels during pregnancy, mainly associated with modifications in erythrocytes and lipid indices, may lead to early modification of genes related to lipid metabolism (APOA1) and proinflammatory response (COX-2) and, thereby, increase cardiovascular disease risk.

Impact of Homocysteine as a Preconceptional Screening Factor for In Vitro Fertilization and Prevention of Miscarriage with Folic Acid Supplementation Following Frozen-Thawed Embryo Transfer: A Hospital-Based Retrospective Cohort Study

Homocysteine is an amino acid naturally produced in the body and metabolized via the methionine cycle. High homocysteine levels can increase the risk of infertility and pregnancy complications, such as preeclampsia, preterm delivery, miscarriage, and low birth weight. Preconceptional homocysteine levels may be reduced by taking folic acid supplements to reduce the risk of such complications. This cross-sectional, hospital-based study was conducted to examine the role of homocysteine in 1060 infertile women with a history of IVF/intracytoplasmic sperm injection (ICSI) failure. We analyzed whether folic acid intervention altered homocysteine levels and influenced reproductive outcome. We found that a higher homocysteine level was statistically associated with a lower fertilization rate in patients with a history of IVF/ICSI failure. There was an inverse relationship between homocysteine levels and serum 25(OH)VD, and a trend towards lower anti mullerian hormone in the group with higher homocysteine levels. This is the first interventional study to identify that folic acid supplementation improved pregnancy outcomes following freeze embryo transfer (FET) in women with a history of FET failure by monitoring the reduction in homocysteine levels. Therefore, folic acid supplementation and homocysteine level monitoring may constitute a novel intervention for improving IVF/ICSI pregnancy outcomes.

Associations between maternal mid-pregnancy apolipoprotein A-1, apolipoprotein B, apolipoprotein B/apolipoprotein A-1 ratio and preterm birth

BACKGROUND AND AIMS

Elevated lipid levels during pregnancy have been shown to be related to the risk of preterm birth. Despite the importance of apolipoprotein (Apo) in lipid metabolism and transportation, evidence regarding apolipoprotein levels during pregnancy and preterm birth is still limited. Therefore, we aim to investigate the associations between maternal ApoA-1, ApoB, ApoB/ApoA-1 ratio and preterm birth.

MATERIALS AND METH

Data were extracted from the information system of Guangdong Women and Children Hospital. Lipoprotein levels were tested using Beckman Coulter AU5800 in mid-pregnancy at a median gestational age of 18 w. Maternal serum ApoB, ApoA-1 and ApoB/ApoA-1 ratio were categorized into tertiles. Logistic regression models were performed to evaluate the odds ratios and 95% confidence intervals for preterm birth.

RESULTS

A total of 5,986 maternal-newborn pairs were included in this study. The rate of preterm birth was 5.7% (n = 344). The multivariate-adjusted ORs (95% CI) of preterm birth were 1.51 (1.06, 2.10) for individuals with high ApoB (>90th), 0.63 (0.38, 0.99) for those with low ApoB (<10th), and 1.64 (1.18, 2.24) for those with high ApoB/ApoA-1 (>90th). Subgroup analyses showed that the association of ApoB and preterm birth was only significant among women with pre-pregnancy BMI 18.5-24 kg/m² (OR = 1.36, 95% CI: 1.12-1.65), age at delivery ≥ 35 years (OR = 1.43, 95% CI: 1.12-1.83).

CONCLUSION

Elevated maternal ApoB level and ApoB/ApoA-1 ratio during mid-pregnancy were related to increased risk of preterm birth. Monitoring maternal serum apolipoprotein levels may help to identify the high-risk population of preterm birth.

5-Methyltetrahydrofolate and Vitamin B12 Supplementation Is Associated with Clinical Pregnancy and Live Birth in Women Undergoing Assisted Reproductive Technology

The homocysteine pathway in the preconception period should be evaluated to highlight micronutrient deficiencies and warrants optimal multivitamin supplementation, before Assisted Reproduction, as preconception care. We conducted a retrospective study aimed at investigating the role of vitamin B complex (5-methyltetrahydrofolate, vitamin B12, vitamin B6) supplement use compared with the role of only folic acid supplement use, in relation to clinical pregnancy and live birth in infertile women undergoing homologous ART. We investigated 269 Caucasian women referred to the Centre for Assisted Reproductive Technology for homologous ART. In these women, 111 (Group A) were daily supplemented with vitamin B complex and 158 (Group B) with only folic acid. In group A the mean number of Metaphase II oocytes and the 2PN Fertilization Rate were higher in comparison to group A (p = 0.04; p = 0.05, respectively). A higher percentage of women in group A had a clinical pregnancy and live birth in comparison to group B (p = 0.01; p = 0.02, respectively). Vitamin B complex supplementation remained independently associated, after multivariable adjustment, with clinical pregnancy (OR 2.03, p = 0.008) and live birth (OR 1.83, p = 0.03). Women supplemented with 5-MTHF and vitamin B12, have a higher chance of clinical pregnancy and live birth in comparison to those supplemented with only folic acid.

Maternal hyperlipidemia and spontaneous preterm delivery: a multi-centre cohort study

BACKGROUND

Hyperlipidemia is a precursor of inflammation and oxidative stress and suggested to be associated with adverse pregnancy outcomes such as preterm delivery. This study evaluated the association between maternal hyperlipidemia and spontaneous preterm delivery.

METHODS

This was a prospective, multicentre cohort study in which 239 pregnant women aged 20-35 years with singleton pregnancy, were consecutively recruited at estimated gestational ages of 14-18weeks. Maternal serum lipids were determined at recruitment over a 2-month period and they were followed up until 37 weeks for the subsequent 6 months. Pregnant women with medical conditions and medications that could alter serum lipid levels were excluded from the study. Demographic and baseline variables were summarized using descriptive statistics. Comparison of continuous variables was done using the student's t-test and categorical variables were compared using the Chi square or Fisher's exact test as appropriate. Correlation was determined using Pearson's correlation. Odd ratios were calculated at 95% confidence interval, width of CI as 10% (0.1) and all significances are reported at p < .05.

FINDINGS

The prevalence of spontaneous preterm delivery and maternal hypercholesterolemia was 10.2% and 33.1% respectively. There was no significant association between spontaneous preterm delivery and hyperlipidemia in pregnancy (p = .102). Mean serum total cholesterol (mmol/L), LDL cholesterol (mmol/L), HDL cholesterol (mmol/L) and triglyceride (mmol/L) was 5.31 ± 0.84, 2.60 ± 0.72, 1.64 ± 0.36 and 1.23 ± 0.40 respectively in women with spontaneous preterm delivery was similar to mean values of 5.23 ± 0.98, 2.54 ± 0.82, 1.64 ± 0.49 and 1.30 ± 0.59 respectively in women with term delivery. There was no significant correlation between mean individual serum lipids, determined at 14-18weeks gestational age, and gestational age at delivery.

CONCLUSION

Serum lipid values determined early in pregnancy were observed to be similar in women with preterm and term delivery. There was no association between hyperlipidemia and spontaneous preterm delivery. There was no correlation of individual mean lipid values, determined early in pregnancy, and gestational age at delivery.

Homocysteine, vitamin B status and MTHFR polymorphisms in Italian infertile women

OBJECTIVE

The purpose of this study was to evaluate the vitamin B status related to the homocysteine pathway and the prevalence of polymorphisms of the MTHFR gene in infertile women programming homologous or heterologous ART.

STUDY DESIGN

We investigated 393 consecutive Caucasian women, referred to the Internal Medicine Clinic at the Center for Assisted Reproductive Technology, in order to be framed for their vascular risk before starting homologous or heterologous (oocyte donation) procedures. Total homocysteine, Vitamin B12, folate and vitamin B6 were measured. The women were divided into quartiles of serum concentration of folate, vitamin B12 and vitamin B6. The C677T and A1298C polymorphisms of the MTHFR gene were genotyped by an electronic microchip technology.

RESULTS

Sixty-one women (15.5%) had hyperhomocysteinemia, 22.9% had reduced levels of vitamin B12, 4.1% had reduced levels of serum folate and 0.1% had a deficiency of vitamin B6. Women in the highest quartile of vitamin B12 and folates had lower homocysteine ​​levels than women in the first and second quartiles (p < 0.0001). The homozygosity for MTHFR C677T polymorphism was detected in 33.3% (131), and heterozygosity for MTHFR C677T polymorphism in 45.3% (178) of women. We observed a significant association between hyperhomocysteinemia and 677T allele, but not 1298C, of the MTHFR polymorphisms (p = 0.04).

CONCLUSIONS

We found inadequate vitamin B status related to the homocysteine ​​pathway in women planning Assisted Reproductive Technology. Moreover, interesting association was found regarding hyperhomocysteinemia in women carrying T allele of the C677T MTHFR polymorphism. A specific supplementation with 5-MTHF and adequate vitamin B12 concentrations before Assisted Reproductive Technology warrant serious consideration, in particular in women carrying T allele of the C677T MTHFR polymorphism.

A Novel Review of Homocysteine and Pregnancy Complications

Homocysteine (Hct) is a substance produced in the metabolism of methionine. It is an essential type of amino acid gained from the daily diet. Methylenetetrahydrofolate reductase (MTHFR) gene mutation is related to elevated total homocysteine (tHct) expressions, in particular, among women with low folate intake. Hyperhomocysteinemia (HHct) is caused by numerous factors, such as genetic defects, lack of folic acid, vitamin B₆ and B₁₂ deficiency, hypothyroidism, drugs, aging, and renal dysfunction. Increased Hct in peripheral blood may lead to vascular illnesses, coronary artery dysfunction, atherosclerotic changes, and embolic diseases. Compared to nonpregnant women, the Hct level is lower in normal pregnancies. Recent studies have reported that HHct was associated with numerous pregnancy complications, including recurrent pregnancy loss (RPL), preeclampsia (PE), preterm delivery, placental abruption, fetal growth restriction (FGR), and gestational diabetes mellitus (GDM). Besides, it was discovered that neonatal birth weight and maternal Hct levels were negatively correlated. However, a number of these findings lack consistency. In this review, we summarized the metabolic process of Hct in the human body, the levels of Hct in different stages of normal pregnancy reported in previous studies, and the relationship between Hct and pregnancy complications. The work done is helpful for obstetricians to improve the likelihood of a positive outcome during pregnancy complications. Reducing the Hct level with a high dosage of folic acid supplements during the next pregnancy could be helpful for females who have suffered pregnancy complications due to HHct.

Association between maternal serum homocysteine concentrations in early pregnancy and adverse pregnancy outcomes

Background

There is still conflicting evidence on the extent to which maternal hyperhomocysteinemia is a risk factor for pregnancy complications.

Aims

The study aimed to investigate the impact of elevated maternal homocysteine concentrations on adverse pregnancy outcomes among Nigerian women in Lagos.

Materials and Methods

This was a prospective cohort study conducted at the Lagos University Teaching Hospital, Idi-Araba, Lagos, Nigeria. Participants were enrolled during the first trimester of pregnancy following which relevant data were obtained by the interview. Fasting blood samples were collected for the measurement of maternal homocysteine concentration using the enzyme-linked immunosorbent assay method. Pregnancy outcomes and complications were obtained by abstracting the antenatal, delivery, and newborn medical records. Preterm births, low-birth weight (LBW), and antepartum fetal death were used as confirmatory outcome variables in the final analysis. Descriptive statistics for all data were computed using SPSS version 22.0. The associations between the variables were tested and multivariate analyses were used to study the effects of the major baseline characteristics on the pregnancy outcome. P < 0.05 was considered statistically significant.

Conclusions

The prevalence of hyperhomocysteinemia among mothers in Lagos was relatively low. The associations between hyperhomocysteinemia and adverse pregnancy outcomes could have implications in future for the prevention of these adverse outcomes.

Results

Hyperhomocysteinemia was recorded in 41 (24.6%) patients. Women with a high homocysteine concentration and those with a normal homocysteine level did not differ significantly in terms of age (P = 0.684), level of education (P = 0.866), and parity (P = 0.647). Women with hyperhomocysteinemia had an approximately twelve-fold higher risk of preterm birth (P = 0.001) and a ten-fold higher risk of delivering a term neonate with LBW (P = 0.004), but had no risk of antepartum fetal death (P = 0.118) compared to women with a normal homocysteine concentration.

Early pregnancy immune profile and preterm birth classified according to uteroplacental lesions

INTRODUCTION

Preterm birth is a heterogeneous phenotype, with placental abnormalities underlying many cases. The etiology of preterm births that occur in the absence of placental abnormalities, however, remain enigmatic and we considered that early pregnancy biomarkers may provide clues.

METHODS

Women from a hospital-based cohort (2008-2012, n = 397) were randomly selected within 6 strata of term and preterm birth with and without placental decidual vasculopathy (arteriopathy), intrauterine inflammation/infection (acute chorioamnionitis), or no lesions. Lipids and inflammatory markers were analyzed in first trimester samples (12.5 ± 0.6 weeks) and related to outcome groups (referent, term births with no lesions). Factor analysis then clustered analytes and related these to preterm birth groups, adjusted for covariates and stratified by pre-pregnancy obesity.

RESULTS

Three biomarker patterns were identified. Immune activation cytokines (33% of the variance) were associated with preterm birth with no lesions (aOR 1.5, 95%CI 1.1-2.1), particularly among obese women. In contrast, inflammatory chemokines (9% of variance) were associated with term and preterm vasculopathy among non-obese women (aOR 2.6 [1.3, 4.7] and 2.0 [1.1, 3.0], respectively).

DISCUSSION

The early pregnancy maternal immune profile is related to preterm births classified according to placental lesions, and these associations vary according to obesity status.

Mouse models of preterm birth: suggested assessment and reporting guidelines

Preterm birth affects approximately 1 out of every 10 births in the United States, leading to high rates of mortality and long-term negative health consequences. To investigate the mechanisms leading to preterm birth so as to develop prevention strategies, researchers have developed numerous mouse models of preterm birth. However, the lack of standard definitions for preterm birth in mice limits our field's ability to compare models and make inferences about preterm birth in humans. In this review, we discuss numerous mouse preterm birth models, propose guidelines for experiments and reporting, and suggest markers that can be used to assess whether pups are premature or mature. We argue that adoption of these recommendations will enhance the utility of mice as models for preterm birth.

Genetic Risk Scores for Maternal Lipid Levels and Their Association with Preterm Birth

Maternal lipid profiles are associated with risk for preterm birth (PTB), although the lipid component and effect size are inconsistent between studies. It is also unclear whether these associations are the result of excessive changes in lipid metabolism during pregnancy or genetic variability in genes controlling basal lipid metabolism. This study investigates the association between genetic risk scores (GRS) for four lipid components (high-density lipoprotein [HDL-C], low-density lipoprotein [LDL-C], triacylglycerols [TAG], and total cholesterol [TC]) with risk for PTB. Subjects included 954 pregnant women from California for whom second trimester serum samples were available, of which 479 gave birth preterm and 475 gave birth at term. We genotyped 96 single-nucleotide polymorphisms, which were selected from genome-wide association studies of lipid levels in adult populations. Lipid-specific GRS were constructed for HDL-C, LDL-C, TAG, and TC. The associations between GRS and PTB were analyzed using logistic regression. A higher HDL-C GRS was associated with increased risk for PTB overall and spontaneous PTB. Higher TAG and TC GRS were associated with decreased risk for PTB overall and spontaneous PTB. This study identifies counter-intuitive associations between lipid GRS and spontaneous PTB. Further replication studies are needed to confirm these findings, but they suggest that our current scientific understanding of the relationship between lipid metabolism, PTB, and genetics is incomplete.

Maternal dyslipidemia and risk for preterm birth

Maternal lipid profiles during pregnancy are associated with risk for preterm birth. This study investigates the association between maternal dyslipidemia and subsequent preterm birth among pregnant women in the state of California. Births were identified from California birth certificate and hospital discharge records from 2007-2012 (N = 2,865,987). Preterm birth was defined as <37 weeks completed gestation and dyslipidemia was defined by diagnostic codes. Subtypes of preterm birth were classified as preterm premature rupture of membranes (PPROM), spontaneous labor, and medically indicated, according to birth certificate data and diagnostic codes. The association between dyslipidemia and preterm birth was tested with logistic regression. Models were adjusted for maternal age at delivery, race/ethnicity, hypertension, pre-pregnancy body mass index, insurance type, and education. Maternal dyslipidemia was significantly associated with increased odds of preterm birth (adjusted OR: 1.49, 95%CI: 1.39, 1.59). This finding was consistent across all subtypes of preterm birth, including PPROM (adjusted OR: 1.54, 95%CI: 1.34, 1.76), spontaneous (adjusted OR: 1.51, 95%CI: 1.39, 1.65), and medically indicated (adjusted OR: 1.454, 95%CI: 1.282, 1.649). This study suggests that maternal dyslipidemia is associated with increased risk for all types of preterm birth.

Maternal plasma cholesterol concentration and preterm birth: a meta-analysis and systematic review of literature

Background: Women that previously had preterm labor are at an increased risk for heart disease. Because spontaneous preterm birth is an adverse pregnancy outcome that affects millions of children worldwide, our objective was to review and analyze studies that have examined associations between maternal total cholesterol (TC), LDL-C, and HDL-C concentrations during pregnancy and the risk of preterm birth to potentially define biomarkers or targets for treatment.Method: A search was performed and 22 articles were found that examined the association of maternal plasma cholesterol concentrations and preterm birth. A meta-analysis was performed on 10 of the articles, those that used maternal lipid concentrations as the outcome and presented results as means plus variables, and a qualitative review was performed on all 22 articles.Results: The meta-analysis showed no relationship between maternal TC, LDL-C, or HDL-C and increased risk of preterm birth, although, a near significant relationship between low maternal HDL-C concentration and preterm birth (p = .055). Importantly, associations increased when cholesterol concentrations were combined with inflammatory markers or metabolic syndrome factors.Conclusions: The relationship between maternal cholesterol levels and preterm birth is heterogeneous. Associations are strengthened when maternal cholesterol concentrations are combined with other factors that may be related to more recently defined lipoprotein functions.

Spontaneous preterm birth: advances toward the discovery of genetic predisposition

Evidence from family and twin-based studies provide strong support for a significant contribution of maternal and fetal genetics to the timing of parturition and spontaneous preterm birth. However, there has been only modest success in the discovery of genes predisposing to preterm birth, despite increasing sophistication of genetic and genomic technology. In contrast, DNA variants associated with other traits/diseases have been identified. For example, there is overwhelming evidence that suggests that the nature and intensity of an inflammatory response in adults and children are under genetic control. Because inflammation is often invoked as an etiologic factor in spontaneous preterm birth, the question of whether spontaneous preterm birth has a genetic predisposition in the case of pathologic inflammation has been of long-standing interest to investigators. Here, we review various genetic approaches used for the discovery of preterm birth genetic variants in the context of inflammation-associated spontaneous preterm birth. Candidate gene studies have sought genetic variants that regulate inflammation in the mother and fetus; however, the promising findings have often not been replicated. Genome-wide association studies, an approach to the identification of chromosomal loci responsible for complex traits, have also not yielded compelling evidence for DNA variants predisposing to preterm birth. A recent genome-wide association study that included a large number of White women (>40,000) revealed that maternal loci contribute to preterm birth. Although none of these loci harbored genes directly related to innate immunity, the results were replicated. Another approach to identify DNA variants predisposing to preterm birth is whole exome sequencing, which examines the DNA sequence of protein-coding regions of the genome. A recent whole exome sequencing study identified rare mutations in genes encoding for proteins involved in the negative regulation (dampening) of the innate immune response (eg, CARD6, CARD8, NLRP10, NLRP12, NOD2, TLR10) and antimicrobial peptide/proteins (eg, DEFB1, MBL2). These findings support the concept that preterm labor, at least in part, has an inflammatory etiology, which can be induced by pathogens (ie, intraamniotic infection) or "danger signals" (alarmins) released during cellular stress or necrosis (ie, sterile intraamniotic inflammation). These findings support the notion that preterm birth has a polygenic basis that involves rare mutations or damaging variants in multiple genes involved in innate immunity and host defense mechanisms against microbes and their noxious products. An overlap among the whole exome sequencing-identified genes and other inflammatory conditions associated with preterm birth, such as periodontal disease and inflammatory bowel disease, was observed, which suggests a shared genetic substrate for these conditions. We propose that whole exome sequencing, as well as whole genome sequencing, is the most promising approach for the identification of functionally significant genetic variants responsible for spontaneous preterm birth, at least in the context of pathologic inflammation. The identification of genes that contribute to preterm birth by whole exome sequencing, or whole genome sequencing, promises to yield valuable population-specific biomarkers to identify the risk for spontaneous preterm birth and potential strategies to mitigate such a risk.

Association Between Factor V Leiden Mutation, Small for Gestational Age, and Preterm Birth: A Systematic Review and Meta-Analysis

OBJECTIVE

To estimate the association of a maternal factor V Leiden (FVL) mutation with SGA and preterm birth.

DATA SOURCES

We performed a search of PubMed, Embase, Scopus, CINAHL, and the Cochrane Library from inception to April 2016 for cohort and case-control studies of women with FVL mutation and associated outcomes of SGA and preterm birth that included a reference group without FVL mutation. Additional studies were identified from reference lists of relevant research and review articles.

STUDY SELECTION

Two authors (JKB, AMO) independently examined the abstracts of the potentially eligible studies, and full texts of eligible studies were retrieved for further evaluation. Disagreements were resolved by consensus. We identified 42 studies suitable for inclusion in the meta-analysis.

DATA EXTRACTION

Thirty-two studies evaluated SGA, and 18 studies assessed preterm birth. Study quality was assessed using the Newcastle Ottawa Scale. A random effects model with inverse variance weighting was used to calculate pooled ORs and 95% CIs. Subgroup analyses were performed by study design.

DATA SYNTHESIS

The overall OR associating FVL mutation with SGA was significant (OR 1.40, 95% CI 1.18 to 1.67). Analysis of 13 cohort studies resulted in an OR of 1.20 (95% CI 1.03 to 1.41), and data from 19 case-control studies yielded an OR of 1.86 (95% CI 1.35 to 2.56). There was no significant association between FVL mutation and preterm birth (OR 1.17, 95% CI 1.00 to 1.37) when all groups were studied, but the association was significant for case-control studies alone (OR 1.40, 95% CI 1.05 to 1.86).

CONCLUSION

There is an increased risk for SGA in pregnancies complicated by FVL mutation in both cohort and case-control study designs. The risk of preterm birth with FVL mutation is less clear, although there is conflicting evidence from cohort and case-control studies regarding the risk of preterm birth associated with FVL mutation.

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.

The Association of Thyroid Function With Maternal and Neonatal Homocysteine Concentrations

CONTEXT

High homocysteine concentrations are associated with maternal pregnancy complications and low birth weight, jaundice, and cerebrovascular accidents in neonates. Thyroid hormone may interfere with homocysteine metabolism via stimulation of vitamin B12- and folate-dependent processes and via effects on enzymes of the remethylation pathway.

OBJECTIVE

Investigating the associations of maternal and neonatal thyroid function with homocysteine during pregnancy and after delivery, respectively.

DESIGN, SETTING, AND PARTICIPANTS

Within Generation R study, a population-based prospective cohort, we studied the associations of maternal and neonatal thyroid stimulating hormone (TSH) and free thyroxine (FT4) with homocysteine, folate, and vitamin B12 concentrations using multiple linear regression analyses.

MAIN OUTCOME MEASURES

TSH, FT4, homocysteine, folate, and vitamin B12 concentrations were determined in early pregnancy (<18 weeks; N = 1094 women without folic acid supplementation) and in cord blood of 4475 neonates.

RESULTS

In neonates, there was a positive association of FT4 with homocysteine and an inverse association of TSH with homocysteine. The associations attenuated after adjustment for folate and vitamin B12 concentration (β change: for FT4, 0.00559 ± 0.001, P < 0.0001, to 0.00310 ± 0.001, P = 0.015; and for TSH, -0.00165 ± 0.001, P = 0.005, to -0.00086 ± 0.001, P = 0.11). In mothers, there was a positive association of FT4 with homocysteine (P = 0.026) but no association of FT4 with folate or vitamin B12 (P ≥ 0.08).

CONCLUSION

Higher thyroid function is associated with higher homocysteine concentrations in pregnant women and in neonates. These data provide new insights into the effects of thyroid hormone on folate- and vitamin B12-dependent processes during early growth and development.

Maternal serum homocysteine and uterine artery Doppler as predictors of preeclampsia and poor placentation

PURPOSE

The aim of this study was to evaluate the role of maternal serum total Homocysteine (tHcy) and uterine artery (Ut-A) Doppler as predictors of preeclampsia (PE), intrauterine growth restriction (IUGR), and other complications related to poor placentation.

PATIENTS AND METHODS

A prospective cohort study was conducted on 500 women with spontaneous pregnancies. tHcy was measured at 15-19 weeks, and then, Ut-A Doppler was performed at 18-22 weeks of pregnancy.

RESULTS

453 pregnant women completed the follow-up of the study. The tHcy and Ut-A resistance index were significantly higher in women who developed PE, IUGR, and other complications when compared to controls (tHcy: 7.033 ± 2.744, 6.321 ± 3.645, and 6.602 ± 2.469 vs 4.701 ± 2.082 μmol/L, respectively, p value <0.001 and Ut-A resistance index: 0.587 ± 0.072, 0.587 ± 0.053, and 0.597 ± 0.069 vs 0.524 ± 0.025, respectively, p value <0.001). The use of both tHcy assessment and Ut-A Doppler improved the sensitivity of prediction of PE relative to the use of each one alone (85.2 relative to 73.33 and 60%, respectively).

CONCLUSION

The use of elevated homocysteine and uterine artery Doppler screening are valuable in prediction of preeclampsia, IUGR, and poor placentation disorders. CLINCALTRIAL.

GOV ID

NCT02854501.

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.

Maternal plasma cholesterol and duration of pregnancy: A prospective cohort study in Ghana

Low plasma cholesterol may be associated with preterm birth; however, results are mixed and limited primarily to high-income countries. Our objective was to determine whether maternal plasma lipid concentrations are associated with pregnancy duration. We performed a nested cohort (n = 320) study of pregnant Ghanaian women enrolled in a randomized controlled trial. Total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol, and triglyceride concentrations were analyzed in plasma at ≤20and 36 weeks gestation as continuous variables and also categorized into low, referent, or high (<10th, 10th-90th, >90th percentile). At ≤20 weeks, plasma lipid concentrations were not associated with pregnancy duration. At 36 weeks, total cholesterol and triglyceride concentrations were not associated with pregnancy duration. Higher HDL-C at 36 weeks was associated with a longer pregnancy duration (adjusted β-coefficient ± standard error: 0.05 ± 0.02 days mg^-1 /dL, p = .02); pregnancy duration was 5.9 ± 2.0 (mean ± standard error) days shorter among women with low HDL-C compared with the referent group (10th-90th percentile) (p = .02) and 8.6 ± 2.6 days shorter when compared with the high HDL-C group (p = .003). Pregnancy duration was 4.9 ± 2.1 days longer among women with low low-density lipoprotein cholesterol at 36 weeks gestation when compared with the referent group (p = .051). Our data suggest that low HDL-C in the third trimester of pregnancy is associated with a shorter duration of pregnancy in this study population but do not support the hypothesis that low total cholesterol is associated with a shorter pregnancy duration.

Excess weight and dyslipidemia and their complications during pregnancy: a systematic review

Abstract Objectives: to identify bibliographically disorders related to excess weight, dyslipidemia and their complication during pregnancy and in the fetus and newborn. Methods: a systematic review including observational and interventional studies and reviews, based on MEDLINE, LILACS, Embase and the Cochrane Library between 2000 and 2015. The key-words "lipids, pregnancy, obesity and newborn" were used to establish a selective stage for inclusion/exclusion of titles, repeated studies, key-words, abstracts, methodological incompatibility and correlation with objectives. Results: 58 studies were selected, of which 36 (62%) addressed prevention and the risk in pregnancy of excess weight and lipid disorders and 19 (32.7%) suggestions and/or consequences for the fetus and newborn. Conclusions: excess weight and lipidemic disorders in pregnancy are causes for concern in scientific studies, posing risks both for the mother and the newborn. Higher prevalence of caesarian and pre-eclampsia were the two most noteworthy complications for gestational outcomes. In short, the impact on care of maternal habits and excess weight during pregnancy is highly significant, owing to the different degrees of complication in obstetric outcomes and their influence on the clinical characteristics of the newborn.

Early pregnancy B vitamin status, one carbon metabolism, pregnancy outcome and child development

Periconception supplementation with folic acid is recommended until 12 gestational weeks to prevent neural tube defects. Doses of folic acid contained in supplements and timing and length of use during pregnancy vary. The effects of status in periconception and pregnancy folate, cobalamin, betaine and their interactions on one carbon metabolism (1C), as well as the global effect of 1C on foetal growth and pregnancy outcome, are reviewed. Results from prospective studies are reviewed. Cessation of folic acid supplement use after the first trimester is associated with a sharp drop in plasma folate status and enhanced conversion of betaine to dimethylglycine. Dimethylglycine production is also higher in mothers with low folate status than in those with normal-high folate status. The effects of high doses of folic acid on one carbon metabolism in mothers with low early pregnancy cobalamin status and on foetal growth are also reviewed. Several studies report that moderately elevated early pregnancy fasting plasma total homocysteine (tHcy) is inversely associated with birth weight and a predictor of intrauterine growth retardation. There is also evidence for increased risk of preterm birth when maternal folate status is low.

The shared pathoetiological effects of particulate air pollution and the social environment on fetal-placental development

Exposure to particulate air pollution and socioeconomic risk factors are shown to be independently associated with adverse pregnancy outcomes; however, their confounding relationship is an epidemiological challenge that requires understanding of their shared etiologic pathways affecting fetal-placental development. The purpose of this paper is to explore the etiological mechanisms associated with exposure to particulate air pollution in contributing to adverse pregnancy outcomes and how these mechanisms intersect with those related to socioeconomic status. Here we review the role of oxidative stress, inflammation and endocrine modification in the pathoetiology of deficient deep placentation and detail how the physical and social environments can act alone and collectively to mediate the established pathology linked to a spectrum of adverse pregnancy outcomes. We review the experimental and epidemiological literature showing that diet/nutrition, smoking, and psychosocial stress share similar pathways with that of particulate air pollution exposure to potentially exasperate the negative effects of either insult alone. Therefore, socially patterned risk factors often treated as nuisance parameters should be explored as potential effect modifiers that may operate at multiple levels of social geography. The degree to which deleterious exposures can be ameliorated or exacerbated via community-level social and environmental characteristics needs further exploration.

Placental lesions associated with acute atherosis

OBJECTIVE

Acute atherosis is a lesion of the spiral arteries characterized by fibrinoid necrosis of the vessel wall, an accumulation of fat-containing macrophages, and a mononuclear perivascular infiltrate, which can be found in patients with preeclampsia, fetal death, small-for-gestational age, spontaneous preterm labor/premature prelabor rupture of membrane, and spontaneous mid-trimester abortion. This lesion is thought to decrease blood flow to the intervillous space which may lead to other vascular lesions of the placenta. The objective of this study was to test whether there is an association between acute atherosis and placental lesions that are consistent with maternal vascular underperfusion (MVU), amniotic fluid infection (AFI), fetal vascular thrombo-occlusive disease (FVTOD) or chronic inflammation.

MATERIAL AND METHODS

A retrospective cohort study of pregnant women who delivered between July 1998 and July 2014 at Hutzel Women's Hospital/Detroit Medical Center was conducted examine 16 457 placentas. The frequency of placenta lesions (diagnosed using the criteria of the Perinatal Section of the Society for Pediatric Pathology) was compared between pregnancies with and without acute atherosis.

RESULTS

Among 16 457 women who were enrolled, 10.2% (1671/16 457) were excluded, leaving 14 786 women who contributed data for analysis. Among them, the prevalence of acute atherosis was 2.2% (326/14 786). Women with acute atherosis were more than six times as likely as those without to have placental lesions consistent with maternal underperfusion (adjusted odds ratio - aOR: 6.7; 95% CI 5.2-8.6). To a lesser degree, acute atherosis was also associated with greater risks of having either lesions consistent with FVTOD (aOR 1.7; 95% CI 1.2-2.3) or chronic chorioamnionitis (aOR 1.9; 95% CI 1.3-3), but not with other chronic inflammatory lesions, after adjusting for gestational age at delivery. In contrast, women with acute atherosis were 60% less likely to have lesions consistent with AFI, adjusting for gestational age at delivery (aOR 0.4; 95% CI 0.3-0.5).

CONCLUSIONS

Acute atherosis is associated with increased risks of having placental lesions consistent with MVU, and to a lesser extent, chronic chorioamnionitis and those consistent with FVTOD.

Combined elevated midpregnancy tumor necrosis factor alpha and hyperlipidemia in pregnancies resulting in early preterm birth

OBJECTIVE

The objective of the study was to determine whether pregnancies resulting in early preterm birth (PTB) (<30 weeks) were more likely than term pregnancies to have elevated midtrimester serum tumor necrosis factor alpha (TNF-α) levels combined with lipid patterns suggestive of hyperlipidemia.

STUDY DESIGN

In 2 nested case-control samples drawn from California and Iowa cohorts, we examined the frequency of elevated midpregnancy serum TNF-α levels (in the fourth quartile [4Q]) and lipid patterns suggestive of hyperlipidemia (eg, total cholesterol, low-density-lipoproteins, or triglycerides in the 4Q, high-density lipoproteins in the first quartile) (considered independently and by co-occurrence) in pregnancies resulting in early PTB compared with those resulting in term birth (n = 108 in California and n = 734 in Iowa). Odds ratios (ORs) and 95% confidence intervals (CIs) estimated in logistic regression models were used for comparisons.

RESULTS

Early preterm pregnancies were 2-4 times more likely than term pregnancies to have a TNF-α level in the 4Q co-occurring with indicators of hyperlipidemia (37.5% vs 13.9% in the California sample (adjusted OR, 4.0; 95% CI, 1.1-16.3) and 26.3% vs 14.9% in the Iowa sample (adjusted OR, 2.7; 95% CI, 1.1-6.3). No differences between early preterm and term pregnancies were observed when TNF-α or target lipid abnormalities occurred in isolation. Observed differences were not explicable to any maternal or infant characteristics.

CONCLUSION

Pregnancies resulting in early PTB were more likely than term pregnancies to have elevated midpregnancy TNF-α levels in combination with lipid patterns suggestive of hyperlipidemia.

Contextualizing racial disparities in preterm delivery: a rhetorical analysis of U.S. epidemiological research at the turn of the 21st century

Preterm delivery (PTD), defined as delivery prior to 37 weeks gestation, is a key contributor to persistent racial disparities in infant mortality in the United States. Five major funding initiatives were devoted to advancing PTD epidemiology during the 1990s and 2000s. By examining content and rhetorical features of 94 studies conducted under these initiatives, and published between 1993 and 2011, this paper considers how calls for more "contextual" approaches (focusing on social and environmental contexts) interacted with more "conventional" approaches (focusing on individual-level risk factors) to PTD epidemiology during this period. Contextual advocates initially emphasized complex biosocial reasoning to better connect social adversity with embodied outcomes. Yet responses by researchers invested in conventional approaches, as well as in studies published under new initiatives that explicitly claimed to incorporate contextual insights, often reframed this complex reasoning in biologically reductionist terms. Subsequent contextual advocates then focused on developing statistical methods to support research about social and environmental causes of PTD, and this strategy appears to have gained some traction with conventional researchers. These findings call for closer attention to language and power in both social scientific studies of epidemiological knowledge production, as well as among epidemiologists themselves.

Revisiting the role of first trimester homocysteine as an index of maternal and fetal outcome

Aim. To revisit the role of first trimester homocysteine levels with the maternal and fetal outcome. Methods. This was a cohort study comprising 100 antenatal women between 8 and 12 weeks of gestation. Serum homocysteine levels were checked after overnight fasting. Results. There were significantly elevated homocysteine levels among women with prior history of hypertensive disorders of pregnancy and prior second or third trimester pregnancy losses. There was no significant difference in homocysteine levels among women with previous gestational diabetes mellitus, preterm deliveries, or fetal malformations. Homocysteine levels were significantly elevated in those who developed hypertensive disorder of pregnancy, oligohydramnios, and meconium stained amniotic fluid, had a pregnancy loss, or delivered a low birth weight baby. There was no significant difference in homocysteine levels for those who developed gestational diabetes mellitus. Conclusions. Increased first trimester serum homocysteine is associated with history of pregnancy losses, hypertensive disorders of pregnancy, and preterm birth. This is also associated with hypertensive disorders of pregnancy, pregnancy loss, oligohydramnios, meconium stained amniotic fluid, and low birth weight in the current pregnancy. This trial is registered with ClinicalTrials.gov CTRI/2013/02/003441.

Normalizing metabolism in diabetic pregnancy: is it time to target lipids?

Outcomes in pregnancies complicated by preexisting diabetes (type 1 and type 2) and gestational diabetes mellitus have improved, but there is still excess morbidity compared with normal pregnancy. Management strategies appropriately focus on maternal glycemia, which demonstrably improves pregnancy outcomes for mother and infant. However, we may be reaching the boundaries of obtainable glycemic control for many women. It has been acknowledged that maternal lipids are important in pregnancies complicated by diabetes. Elevated maternal lipids are associated with preeclampsia, preterm delivery, and large-for-gestational-age infants. Despite this understanding, assessment of management strategies targeting maternal lipids has been neglected to date. Consideration needs to be given to whether normalizing maternal lipids would further improve pregnancy outcomes. This review examines the dyslipidemia associated with pregnancy complicated by diabetes, reviews possible therapies, and considers whether it is time to start actively managing this aspect of maternal metabolism.

The MTHFD1 1958G>A variant is associated with elevated C-reactive protein and body mass index in Canadian women from a premature birth cohort

MTHFD1 1958G>A, a polymorphism in folate metabolism, increases risk of pregnancy complications. A mouse model exhibited developmental defects, increased weight and decreased leukocyte counts. To examine the latter associations, we genotyped 651 women from a premature birth cohort. Prematurity and 1958G>A were not associated. Increases in the inflammatory marker CRP (logistic regression, p = 0.055) and BMI (chi-square, p = 0.0113) were associated with AA genotype in women with low folate. MTHFD1 1958G>A may influence immune function and obesity.

Maternal lipids and small for gestational age birth at term

OBJECTIVE

To compare maternal lipid and lipoprotein concentrations between small for gestational age (SGA) infants and infants with normal growth born at term.

STUDY DESIGN

This was a case-control study nested within a large (n = 5337) prospective multicenter cohort of pregnant women followed to delivery. SGA cases (n = 323) were all term infants with birth weight below the 10th percentile for their gestational age and sex. Controls (n = 671) were selected at random from term infants with birth weight between the 25th and 75th percentiles. Plasma samples obtained at 24-26 weeks were analyzed for lipoproteins using a recently developed nuclear magnetic resonance-based procedure that distinguishes high-density lipoprotein (HDL) and low-density lipoprotein particles of different sizes. Apolipoprotein A-1 and C-II levels were analyzed using turbidimetric methods.

RESULTS

Compared with controls, mothers of SGA cases had significantly higher mean concentrations of total HDL particles, medium and small HDL particles, and apolipoprotein A-1, with evidence of a dose-response relationship across quartiles of the control distribution. aORs for the highest quartiles were 2.8 (95% CI, 1.7-4.5) for total HDL particles and 3.1 (95% CI, 1.9-5.0) for apolipoprotein A-1.

CONCLUSION

Our results suggest that the higher HDL particle and apolipoprotein A-1 concentrations in mothers of SGA cases may reflect defective placental transport of HDL, which could compromise cholesterol uptake by the developing fetus.

The role of folic acid in fetal programming of birth phenotypes and early human development: a biopsychosocial perspective

Preterm birth, low birthweight, intrauterine growth retardation and small for gestational age are birth phenotypes that significantly contribute to life-long morbidity and mortality. This review examines the epidemiologic and biologic evidence of folic acid (FA) as a potential population-based intervention to curtail some adverse birth phenotypic expressions, and by extension, their later physical and neurodevelopmental consequences. We outlined a feto-placental adaptation categorization taking into account how prenatal insults may be encoded in fetal development, the adaptive success of the feto-placental response, and subsequent expression in the health of the fetus. Although there are plausible biological pathways that can be implicated, we found that the epidemiological evidence on the role of perinatal FA nutriture and fetal programming of adverse birth phenotypes is still inconclusive. Because biologic and epidemiological considerations alone do not suffice in deciphering the utility of FA in averting adverse birth phenotypes, we proposed a biopsychosocial model that takes into account multi-layered psychosocial contexts for improving subsequent research studies in this area.

Hyperhomocysteinemia is detrimental to pregnancy in mice and is associated with preterm birth

Elevated levels of homocysteine produce detrimental effects in humans but its role in preterm birth is not known. Here we used a mouse model of hyperhomocysteinemia to examine the relevance of homocysteine to preterm birth. The mouse carries a heterozygous deletion of cystathionine β-synthase (Cbs(+/-)). Gestational period was monitored in wild type and Cbs(+/-) female mice. Mouse uterine and placental tissues, human primary trophoblast cells, and human myometrial and placental cell lines were used to determine the influence of homocysteine on expression of specific genes in vitro. The activity of BKCa channel in the myometrial cell line was monitored using the patch-clamp technique. We found that hyperhomocysteinemia had detrimental effects on pregnancy and induced preterm birth in mice. Homocysteine increased the expression of oxytocin receptor and Cox-2 as well as PGE2 production in uterus and placenta, and initiated premature uterine contraction. A Cox-2 inhibitor reversed these effects. Gpr109a, a receptor for niacin, induced Cox-2 in uterus. Homocysteine upregulated GPR109A and suppressed BKCa channel activity in human myometrial cells. Deletion of Gpr109a in Cbs(+/-) mice reversed premature birth. We conclude that hyperhomocysteinemia causes preterm birth in mice through upregulation of the Gpr109a/Cox-2/PGE2 axis and that pharmacological blockade of Gpr109a may have potential in prevention of preterm birth.

Homocysteine and folate concentrations in early pregnancy and the risk of adverse pregnancy outcomes: the Generation R Study

OBJECTIVE

To investigate associations between early pregnancy homocysteine, folate and vitamin B12 concentrations and placental weight, birthweight and adverse pregnancy outcomes.

DESIGN

Population-based birth cohort study.

SETTING

Rotterdam, the Netherlands.

POPULATION

Cohort of 5805 pregnant women.

METHODS

To analyse homocysteine, folate and vitamin B12 concentrations, blood was drawn in early pregnancy. These concentrations were divided into quintiles. Information on birth outcomes was retrieved from medical records. Multivariate regression analyses were used.

MAIN OUTCOME MEASURES

Placental weight, birthweight, small for gestational age at birth (SGA) (<5th centile), prematurity and pre-eclampsia.

RESULTS

High homocysteine concentrations (highest quintile) were associated with lower placental weight (difference 30 g; P < 0.001) and birthweight (difference 110 g; P < 0.001), and increased risk of SGA [odds ratio (OR) 1.7; P = 0.006] compared with lowest quintile (reference). Low folate concentrations (lowest quintile) were associated with lower placental weight (difference 26 g; P = 0.001) and birthweight (difference 125 g; P < 0.001), and increased risks of SGA (OR 1.9; P = 0.002), prematurity (OR 2.2; P = 0.002) and pre-eclampsia (OR 2.1; P = 0.04) compared with highest quintile (reference). The risk of developing SGA and pre-eclampsia was substantially higher in women who had higher homocysteine and lower folate concentrations. No associations were found with vitamin B12.

CONCLUSIONS

Higher homocysteine and lower folate concentrations in early pregnancy are associated with lower placental weight and birthweight, and higher risk of adverse pregnancy outcomes. These findings suggest that high homocysteine and low folate concentrations in early pregnancy may adversely influence placentation and subsequently affect the success of pregnancy and birth outcomes.

Maternal lipids at mid-pregnancy and the risk of preterm delivery

OBJECTIVE

This study examined associations between maternal lipid levels at mid-pregnancy and preterm delivery, medically indicated or spontaneous.

DESIGN

Prospective cohort study.

SETTING

Women were recruited from 52 clinics in five Michigan, USA communities (1998-2004).

POPULATION

Pregnant women were enrolled at 15-27 weeks' gestation and followed to delivery (n=3019).

METHODS

A single blood sample was obtained at study enrollment. Blood lipids, i.e. total cholesterol (TC), high-density lipoprotein (HDLc), low-density lipoprotein (LDLc) cholesterol, and triglycerides (TG), were measured on a sub-cohort (n=1309).

MAIN OUTCOME MEASURES

There were 221 spontaneous, 100 medically indicated preterm deliveries and 988 term deliveries. Polytomous logistic regression models examined relationships among cholesterol levels (Low: <10(th) percentile, Referent: 10(th) -<70(th) percentile, High: ≥70(th) percentile), quartiles of TG (Referent: first quartile) and delivery outcome (Referent: term).

RESULTS

Odds of medically indicated preterm delivery were increased among women with low TC (adjusted odds ratio (aOR)=2.04, 95% confidence interval (CI): 1.12, 3.72), low HDLc (aOR=1.89, 95%CI: 1.04, 3.42) or low LDLc (aOR=1.96, 95%CI: 1.09, 3.54). Odds of spontaneous preterm delivery were increased among women with high TC (aOR=1.51, 95%CI: 1.06, 2.15), high LDLc (aOR=1.42, 95%CI: 0.99, 2.04) or high TG (aOR=1.90, 95%CI: 1.21, 2.97 and aOR=1.72, 95%CI: 1.06, 2.78 for third and fourth quartiles, respectively).

CONCLUSIONS

Extremely low TC, HDLc, and LDLc were associated with a modest increase in risk of medically indicated preterm delivery, whereas high TC, LDLc and TG modestly increased the risk of spontaneous preterm delivery. Further research is needed to uncover explanations for these associations and to identify optimal ranges for maternal lipids.

California Very Preterm Birth Study: design and characteristics of the population- and biospecimen bank-based nested case-control study

Very preterm birth (VPTB) is a leading cause of infant mortality, morbidity and racial disparity in the US. The underlying causes of VPTB are multiple and poorly understood. The California Very Preterm Birth Study was conducted to discover maternal and infant genetic and environmental factors associated with VPTB. This paper describes the study design, population, data and specimen collection, laboratory methods and characteristics of the study population. Using a large, population-based cohort created through record linkage of livebirths delivered from 2000 to 2007 in five counties of southern California, and existing data and banked specimens from statewide prenatal and newborn screening, 1100 VPTB cases and 796 control mother-infant pairs were selected for study (385/200 White, 385/253 Hispanic and 330/343 Black cases/controls, respectively). Medical record abstraction of cases was conducted at over 50 hospitals to identify spontaneous VPTB, improve accuracy of gestational age, obtain relevant clinical data and exclude cases that did not meet eligibility criteria. VPTB was defined as birth at <32 weeks in Whites and Hispanics and <34 weeks in Blacks. Approximately 55% of all VPTBs were spontaneous and 45% had medical indications or other exclusions. Of the spontaneous VPTBs, approximately 41% were reported to have chorioamnionitis. While the current focus of the California Very Preterm Birth Study is to assess the role of candidate genetic markers on spontaneous VPTB, its design enables the pursuit of other research opportunities to identify social, clinical and biological determinants of different types of VPTB with the ultimate aim of reducing infant mortality, morbidity and racial disparities in these health outcomes in the US and elsewhere.

Does pregnancy or pregnancy loss increase later maternal risk of diabetes?

Evidence that childbearing is associated with future development of diabetes remains conflicting and the role of pregnancy loss in this association has not been investigated. We aimed to examine whether pregnancy and/or pregnancy loss (miscarriage, abortion, or stillbirth) are associated with maternal higher risk of diabetes later in life, using a population-based prospective cohort study (mean follow-up = 10.7 years), including 13,612 women (aged 35-65 at baseline). We found pregnancy per se did not change the risk of diabetes after considering the effect of education, smoking, alcohol consumption, physical activity, BMI, waist/hip ratio, hypertension, and hyperlipidemia (fully-adjusted OR: 1.04, 95 % CI: 0.82-1.31). Having more than four live births was associated with around two times higher risk of diabetes later in life (fully-adjusted OR: 1.77, 95 % CI: 1.12-2.80). Having more than two miscarriages was associated with about two-fold higher risk of diabetes (fully-adjusted Odd ratio (OR): 1.85, 95 % CI: 1.17-2.93). After further adjustment for parity, the higher risk of diabetes in those who had history of more than two miscarriages did not change substantially (OR: 1.82; 95 % CI: 1.15-2.88), but the association between more than four live births and diabetes disappeared when the role of pregnancy loss was considered (fully-adjusted HR: 1.06; 95 % CI: 0.54-2.08). No significant association was found between abortion, stillbirth and risk of maternal diabetes. Pregnancy per se did not increase risk of diabetes. Women who experience more than two miscarriages are at around two times higher risk of diabetes later in life. The association between high parity and diabetes is mediated by history of miscarriages and known risk factors of diabetes. The underlying reason for association between miscarriage and diabetes needs further investigation.

Impact of fetal versus perinatal hypoxia on sex differences in childhood outcomes: developmental timing matters

PURPOSE

To examine how the timing of hypoxic exposure results in specific childhood outcomes and whether there is a differential effect by sex.

METHODS

A sample of 10,879 prospectively followed pregnancies was drawn from the Boston and Providence sites (New England, NE) of the National Collaborative Perinatal Project. Based on placental pathology, we developed and validated a measure of probable chronic placental hypoxia (CHP) and contrasted the effects of acute perinatal hypoxia on age 7 emotional, behavioral, and cognitive outcomes.

RESULTS

Perinatal hypoxia had a significant impact on multiple behavioral and cognitive outcomes in boys and girls by age 7, in contrast to probable CHP which had a differential effect on girls and boys such that there was decreased verbal IQ and increased inhibition in females alone.

CONCLUSIONS

Findings underscore the importance of considering the timing of obstetric complications and offspring sex in investigations of the impact of fetal and perinatal hypoxia on offspring's outcomes throughout the life course.

Cardiovascular risk factors prior to conception and the length of pregnancy: population-based cohort study

OBJECTIVE

To study the association of prepregnancy blood pressure, lipids, and glucose with length of pregnancy, and to assess whether the association between preterm delivery and later maternal cardiovascular disease may be due to common risk factors.

STUDY DESIGN

Prospective study linking information of 3506 women in the HUNT Study with 4990 singleton births recorded in the Medical Birth Registry of Norway.

RESULTS

Unfavorable prepregnancy levels of triglycerides, cholesterol, high-density lipoprotein-cholesterol, and glucose were associated with increased risk of preterm birth and shorter gestational length. Triglycerides above 1.6 mmol/L were associated with 60% higher risk of preterm birth (odds ratio, 1.6, 95% confidence interval, 1.0-2.5), compared with triglycerides below 0.7 mmol/L. Blood pressure was positively associated with risk of preterm birth and shorter gestational length, but these associations were substantially attenuated after adjustment for hypertensive disorders in pregnancy.

CONCLUSION

Women with unfavorable cardiovascular risk factors before conception have excess risk of preterm birth.

Homocysteine in pregnancy

The aim of this review is to evaluate the evidence for and against fasting plasma total homocysteine (tHcy) as a biomarker/risk factor of impaired reproductive function before and during pregnancy. Apart from nutritional and lifestyle factors, tHcy is also influenced by physiological factors specific to pregnancy such as hemodilution, increased glomerular filtration rate, and endocrinological changes. These lead to a considerable reduction under normal circumstances in tHcy by midpregnancy. Stimulating excess endogenous homocysteine production before and during pregnancy in animal experiments and adding exogenous homocysteine to cell cultures result in the impairment of reproductive and developmental processes from preconception throughout pregnancy and during subsequent development of the offspring. Different studies have confirmed that elevated tHcy is a risk factor for subfertility, congenital developmental defects, preeclampsia, and intrauterine growth retardation. There is conflicting evidence that elevated tHcy is a risk factor for miscarriage, gestational diabetes, premature rupture of the membranes, placental abruption, and offspring with Down syndrome. Prospective, sufficiently powered, studies from preconception/early pregnancy are required to determine whether tHcy is a risk factor for these pregnancy complications.

Factor V Leiden as a risk factor for preterm birth--a population-based nested case-control study

BACKGROUND

Preterm birth is a major cause of neonatal morbidity and mortality, occurring in 5-13% of deliveries in developed countries. Genetic thrombophilia can theoretically contribute to the induction of preterm delivery, but the role of thrombophilia as risk factor is unclear.

OBJECTIVES

To assess factor V Leiden, FII G20210A and other selected inherited and acquired variables as risk factors for preterm birth.

PATIENTS/METHODS

We performed a population-based nested case-control study of 100,000 consecutive pregnancies in Finland. Cases and controls were identified by combining national registers. Clinical data were obtained from medical records and standardized questionnaires. We studied 324 cases with preterm delivery at or after 22 and before 37 completed weeks of gestation, and 752 controls.

RESULTS

FV Leiden was associated with a 2.4-fold risk (95% confidence interval [CI] 1.3-4.6) of preterm birth in all pregnancies, and a 2.6-fold risk (95% CI 1.4-5.1) in singleton pregnancies. FV Leiden was especially associated with late preterm birth at or after 32 weeks of pregnancy, with an odds ratio (OR) of 2.9 (95% CI 1.5-5.6) in all pregnancies and an OR of 3.1 (95% CI 1.6-6.2) in singleton pregnancies. FII G20210A was not associated with preterm birth. Twin pregnancy (OR 12.0, 95% CI 6.0-24.1) and a history of venous thrombosis (OR 3.8, 95% CI 1.4-9.8) were associated with increased risk. High educational level and modest overweight (body mass index 25-29.9 kg m(-2) ) had protective effects.

CONCLUSIONS

Maternal carriage of FV Leiden was associated with increased risk of late but not early preterm birth. FII G20120A was not associated with preterm birth.

A genetic association study of maternal and fetal candidate genes that predispose to preterm prelabor rupture of membranes (PROM)

OBJECTIVE

We sought to determine whether maternal/fetal single-nucleotide polymorphisms (SNPs) in candidate genes are associated with preterm prelabor rupture of membranes (pPROM).

STUDY DESIGN

A case-control study was conducted in patients with pPROM (225 mothers and 155 fetuses) and 599 mothers and 628 fetuses with a normal pregnancy; 190 candidate genes and 775 SNPs were studied. Single locus/haplotype association analyses were performed; false discovery rate was used to correct for multiple testing (q* = 0.15).

RESULTS

First, a SNP in tissue inhibitor of metalloproteinase 2 in mothers was significantly associated with pPROM (odds ratio, 2.12; 95% confidence interval, 1.47-3.07; P = .000068), and this association remained significant after correction for multiple comparisons. Second, haplotypes for Alpha 3 type IV collagen isoform precursor in the mother were associated with pPROM (global P = .003). Third, multilocus analysis identified a 3-locus model, which included maternal SNPs in collagen type I alpha 2, defensin alpha 5 gene, and endothelin 1.

CONCLUSION

DNA variants in a maternal gene involved in extracellular matrix metabolism doubled the risk of pPROM.

A functional polymorphism in the reduced folate carrier gene and DNA hypomethylation in mothers of children with autism

The biologic basis of autism is complex and is thought to involve multiple and variable gene-environment interactions. While the logical focus has been on the affected child, the impact of maternal genetics on intrauterine microenvironment during pivotal developmental windows could be substantial. Folate-dependent one carbon metabolism is a highly polymorphic pathway that regulates the distribution of one-carbon derivatives between DNA synthesis (proliferation) and DNA methylation (cell-specific gene expression and differentiation). These pathways are essential to support the programmed shifts between proliferation and differentiation during embryogenesis and organogenesis. Maternal genetic variants that compromise intrauterine availability of folate derivatives could alter fetal cell trajectories and disrupt normal neurodevelopment. In this investigation, the frequency of common functional polymorphisms in the folate pathway was investigated in a large population-based sample of autism case-parent triads. In case-control analysis, a significant increase in the reduced folate carrier (RFC1) G allele frequency was found among case mothers, but not among fathers or affected children. Subsequent log linear analysis of the RFC1 A80G genotype within family trios revealed that the maternal G allele was associated with a significant increase in risk of autism whereas the inherited genotype of the child was not. Further, maternal DNA from the autism mothers was found to be significantly hypomethylated relative to reference control DNA. Metabolic profiling indicated that plasma homocysteine, adenosine, and S-adenosylhomocyteine were significantly elevated among autism mothers consistent with reduced methylation capacity and DNA hypomethylation. Together, these results suggest that the maternal genetics/epigenetics may influence fetal predisposition to autism.

Identification of fetal and maternal single nucleotide polymorphisms in candidate genes that predispose to spontaneous preterm labor with intact membranes

OBJECTIVE

The purpose of this study was to determine whether maternal/fetal single nucleotide polymorphisms (SNPs) in candidate genes are associated with spontaneous preterm labor/delivery.

STUDY DESIGN

A genetic association study was conducted in 223 mothers and 179 fetuses (preterm labor with intact membranes who delivered <37 weeks of gestation [preterm birth (PTB)]), and 599 mothers and 628 fetuses (normal pregnancy); 190 candidate genes and 775 SNPs were studied. Single locus/haplotype association analyses were performed; the false discovery rate was used to correct for multiple testing.

RESULTS

The strongest single locus associations with PTB were interleukin-6 receptor 1 (fetus; P=.000148) and tissue inhibitor of metalloproteinase 2 (mother; P=.000197), which remained significant after correction for multiple comparisons. Global haplotype analysis indicated an association between a fetal DNA variant in insulin-like growth factor F2 and maternal alpha 3 type IV collagen isoform 1 (global, P=.004 and .007, respectively).

CONCLUSION

An SNP involved in controlling fetal inflammation (interleukin-6 receptor 1) and DNA variants in maternal genes encoding for proteins involved in extracellular matrix metabolism approximately doubled the risk of PTB.

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

OBJECTIVE

Preterm delivery has been shown to be associated with subsequent maternal cardiovascular morbidity. However, the impact of the severity and recurrence of preterm delivery on the risk of specific cardiovascular events and the metabolic syndrome in the mother, have not been investigated.

DESIGN

National registry-based retrospective cohort study.

SETTING

Women delivering in Denmark from 1978 to 2007.

POPULATION

Women with a first singleton delivery (n = 782 287), and with a first and second singleton delivery (n = 536 419).

METHODS

Cox proportional hazard models, with the gestational age stratified into four groups as primary exposure. We made adjustments for maternal age, year of delivery, hypertensive pregnancy disorders, fetal growth deviation, placental abruption and stillbirth.

MAIN OUTCOME MEASURES

Subsequent maternal hypertension, ischaemic heart diseases, thromboembolism and type-II diabetes.

RESULTS

After a first delivery at 32-36 completed weeks of gestation, the adjusted risk of subsequent type-II diabetes increased 1.89-fold (1.69-2.10) and the risk of thromboembolism increased 1.42-fold (1.24-1.62). Women having a preterm delivery in the first pregnancy and a term delivery in the second had a 1.58-fold (1.34-1.86) increased risk of type-II diabetes and a 1.18-fold (0.96-1.44) increased risk of thromboembolism. Women having two preterm deliveries had a 2.30-fold (1.71-3.10) increased risk of type-II diabetes and a 1.80-fold (1.29-2.50) increased risk of thromboembolism.

CONCLUSIONS

Preterm delivery is independent of other pregnancy complications associated with subsequent maternal overt type-II diabetes and thromboembolism. The recurrence of preterm delivery will augment these risks.