Maternal Diet, C-Reactive Protein, and the Outcome of Pregnancy

Cohort profile: The Camden Study - a pregnancy cohort study of pregnancy complications and birth outcomes in Camden, New Jersey, USA

Background

Pregnancy is a unique stage of the life course characterized by trade-offs between the nutritional, immune, and metabolic needs of the mother and fetus. The Camden Study was originally initiated to examine nutritional status, growth, and birth outcomes in adolescent pregnancies and expanded to study dietary and molecular predictors of pregnancy complications and birth outcomes in young women.

Methods

From 1985-2006, 4765 pregnant participants aged 12 years and older were recruited from Camden, NJ, one of the poorest cities in the U.S. The cohort reflects a population under-represented in perinatal cohort studies (45% Hispanic, 38% non-Hispanic Black, 17% White participants; 98% using Medicaid in pregnancy). Study visits, including questionnaires, dietary assessments, and biospecimen collection, occurred in early and late pregnancy as well as at delivery. Medical records were abstracted, and a subset of mothers and infants participated in a six-week postpartum visit.

Results

Over the last five decades, the Camden Study has provided data toward the publication of numerous peer-reviewed papers. Results show that adolescent linear growth in pregnancy is associated with smaller birth size, possibly due to impaired hemodynamics. In the context of preterm birth and other perinatal outcomes, analyses of nutritional data have demonstrated the importance of micronutrients (e.g., folate, iron, zinc), as well as glucose/insulin dynamics and prenatal supplement use. More recent analyses have begun to unpack the biochemical pathways in pregnancy that may be shaped by race as an indicator for systemic racism.

Conclusions

The Camden Study data and biorepositories are well-positioned to support future research aimed at better understanding perinatal health in under-represented women and infants. Linkages to subsequent health and administrative records and the potential for recontacting participants over 18-39 years after initial participation may provide key insights into the trajectories of maternal and child health across the life course.

Urinary 8-hydroxy-2'-deoxyguanosine levels and preterm births: a prospective cohort study from the Japan Environment and Children's Study

OBJECTIVES

To evaluate the association between urinary 8-hydroxy-2'-deoxyguanosine (U8-OHdG) level-a marker of oxidative stress-and the incidence of preterm births (PTBs).

DESIGN

Prospective cohort study.

SETTING

The Japan Environment and Children's Study (JECS).

PARTICIPANTS

Data from 92 715 women with singleton pregnancies at and after 22 weeks of gestation who were enrolled in the JECS, a nationwide birth cohort study, between 2011 and 2014 were analysed. U8-OHdG levels were assessed once in the second/third trimester using liquid chromatography-tandem mass spectrometry. Participants were categorised into the following three or five groups: low (<1.95 ng/mg urinary creatinine (Cre)), moderate (1.95-2.94 ng/mg Cre) and high (≥2.95 ng/mg Cre) U8-OHdG groups, or groups with <1.87, 1.87-2.20, 2.21-2.57, 2.58-3.11 and ≥3.12 ng/mg Cre. For stratification, participants with representative causes for artificial PTB were excluded.

PRIMARY AND SECONDARY OUTCOME MEASURES

Adjusted OR (aOR) for PTB before 37 and 34 weeks of gestation were calculated using a multivariable logistic regression model while adjusting for confounding factors; the moderate or lowest U8-OHdG group was used as the reference, respectively.

RESULTS

The aORs for PTB before 37 weeks of gestation in the high U8-OHdG group were 1.13 (95% CI 1.05 to 1.22) and 1.13 (95% CI 1.04 to 1.23) after stratification. The aOR for PTB before 37 weeks in the fourth group was 0.90 (95% CI 0.81 to 0.99). After stratification, the aORs for PTB before 37 and 34 weeks in the fifth group were 1.15 (95% CI 1.03 to 1.29) and 1.46 (95% CI 1.08 to 1.97), respectively.

CONCLUSIONS

High U8-OHdG levels were associated with increased PTB incidence, especially in participants without representative causes for artificial PTB. Our results can help identify the mechanisms leading to PTB, considering the variable aetiologies of this condition; further validation is needed to clarify clinical impacts.

C-Reactive Protein for Prediction or Early Detection of Pre-Eclampsia: A Systematic Review

OBJECTIVE

Pre-eclampsia (PE) is a serious disease of pregnancy and one of the major causes of morbidity and mortality for both the mother and baby. This systematic review aims to detect the role of high-sensitivity C-reactive protein (CRP) in the detection of PE.

METHODS

Thirty-four articles published between 2001 and 2019 were included in this review. The articles were extracted from OVID Medline and Embase. The study designs of these articles are randomized controlled, cohort, case-control, and cross-sectional studies evaluating CRP as a marker to predict or early diagnose PE. The quality assessment of these articles is made by the modified Quality Assessment of Diagnostic Accuracy Studies 2 tool. Meta-analysis was not done because of clinical and statistical heterogeneity.

RESULTS

A positive association between CRP levels and the development of PE was confirmed in 18 studies. This positive effect was addressed in patients with normal BMI (<25 kg/m2) in 3 studies and in overweight patients in 2 studies. One study addressed this positive association in patients with a BMI ranging between 28 and 31 kg/m2. Three studies determined a cutoff level of CRP above which a significant risk of PE development should be suspected. These levels ranged between 7 and 15 mg/L.

CONCLUSION

CRP is a promising cost-effective biomarker that may be used in the prediction of PE. A CRP level higher than 15 mg/L may suggest initiation of low-dose aspirin in low-risk pregnancies.

Associations between Dietary Patterns and Inflammatory Markers during Pregnancy: A Systematic Review

Elevated inflammation in pregnancy has been associated with multiple adverse pregnancy outcomes and potentially an increased susceptibility to future chronic disease. How maternal dietary patterns influence systemic inflammation during pregnancy requires further investigation. The purpose of this review was to comprehensively evaluate studies that assessed dietary patterns and inflammatory markers during pregnancy. This review was guided by the Preferred Reporting Items for Systematic Review and Meta-Analyses. Included studies were sourced from EMBASE, PubMed, Web of Science, and Scopus and evaluated using The Quality Assessment Tool for Quantitative Studies. Inclusion criteria consisted of human studies published in English between January 2007 and May 2020 that addressed associations between dietary patterns and inflammatory markers during pregnancy. Studies focused on a single nutrient, supplementation, or combined interventions were excluded. A total of 17 studies were included. Despite some inconsistent findings, maternal diets characterized by a higher intake of animal protein and cholesterol and/or a lower intake of fiber were shown to be associated with certain pro-inflammatory markers (C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-α (TNF- α), IL-8, serum amyloid A (SAA), and glycoprotein acetylation (GlycA)). Future studies that explore a broader range of inflammatory markers in the pregnant population, reduce measurement errors, and ensure adequate statistical adjustment are warranted.

Effect of proinflammatory diet before pregnancy on gestational age and birthweight: The Japan Environment and Children's Study

The daily diet plays a role in systematic inflammation and may be one of the causes of preterm birth. We aimed to examine the effect of a daily proinflammatory diet before pregnancy on gestational age and birthweight using a large birth cohort in Japan. We used data of singleton pregnancies in the Japan Environment and Children's Study involving live birth from 2011 to 2014 to calculate the dietary inflammatory index. We used individual meals with 30 food parameters from a semiquantitative food frequency questionnaire, which assessed diet intake before pregnancy. Participants were categorized according to the quartile of dietary inflammatory index. A multiple logistic regression model was used to estimate the risk of a proinflammatory diet on preterm birth (PTB) before 37 or 34 weeks and low birthweight (LBW) less than 2,500 or 1,500 g, accounting for maternal age, body mass index before pregnancy, smoking status, education, and household income. After applying our inclusion criteria, 89,329 participants were eligible for the present study. Multiple regression analysis showed that the proinflammatory diet had an increased risk of PTB < 34 weeks (adjusted odds ratio: 1.29, 95% confidence interval [1.07, 1.55]) and <2,500‐g LBW (adjusted odds ratio: 1.08, 95% confidence interval [1.01, 1.16]) compared with the control. In conclusion, a proinflammatory diet before pregnancy was a risk factor for PTB < 34 weeks and LBW < 2,500 g. Therefore, proinflammatory diet needs to be controlled to improve perinatal prognosis.

Evaluation of Some Cytokines and Gene Expressions in Pre-eclampsia

BACKGROUND AND OBJECTIVE

Preeclampsia(PE) is adisordercharacterized byhypertensionandproteinuria. There is accumulating evidence that this is a disease of the endothelium. Angiogenic factors may be responsible for the regulation of placental vascular development. Clinicians cannot predict pre-eclampsia prior to the onset symptoms. An ideal bio-marker for pre-eclampsia prediction is during the first trimester. This study investigated the serum levels of tumor necrosis factor-α (TNF-α), C-reactive protein (CRP) and the gene expressions of vascular endothelial growth factor (VEGF), endothelial nitric oxide synthase (eNOS) and p53 in PE trying to find out potential bio-markers for prediction and diagnosis of PE.

MATERIAL AND METHODS

A total of 100 female volunteers were involved in this study and their ages were ranged from 25-35 years. They were divided into three groups: Group (1) was 20 healthy non-pregnant women, group (2) was 20 pregnant women normal pregnancies and group (3) was 60 preeclamptic patients. The study participants were enrolled at the Department of Obstetrics and Gynaecology at Mansoura University Hospital, Mansoura, Egypt. The study was approved by the Research Ethics Committee (Faculty of Science, Al Azhar University, Egypt) approved on the March 15, 2014) all women gave written informed consent. Serum levels of CRP, IL-10 and TNF-α were evaluated, in addition to the gene expression of VEGF, eNOS and p53.

RESULTS

Significant elevations in the serum levels of blood pressure, TNF-α and CRP were observed in PE patients. Additionally, the gene expression of VEGF, eNOS and P53 were down-regulated in preeclampsia.

CONCLUSION

Elevated serum levels of TNFα and CRP, in addition to the down-regulation of eNOS may be used as good predictors for preeclampsia. The TNF-α and VEGF gene were recommended used as markers for PE to be added to routine testes of pregnant women.

Relationship between inflammatory markers, glycated hemoglobin and placental weight on fetal outcomes in women with gestational diabetes

OBJECTIVE

The aim of this study was to evaluate the relationship between inflammatory cytokines, placental weight, glycated hemoglobin and adverse perinatal outcomes (APOs) in women with gestational diabetes mellitus (GDM).

SUBJECTS AND METHODS

This was a prospective, longitudinal and observational study conducted from April 2004 to November 2005 in Bauru, Brazil. Included patients had singleton pregnancies and performed a 100 g OGTT and had the levels of C-reactive protein (CRP), interleukin (IL)-6, TNF alfa and glycated hemoglobin (HbA1c) determined at 24-28th gestation weeks.

RESULTS

A total of 176 patients were included, of whom 78 had the diagnosis of GDM (44.3%). Multivariate analysis demonstrated that HbA1c, age, body mass index (BMI) and previous history of GDM were independent predictors for GDM diagnosis. ROC curve indicated that HbA1C levels ≥ 5.1% at 24-28 weeks gestation were associated with GDM. No difference was found in IL-6, tumor necrosis factor alpha (TNF-alpha) and CRP serum levels in women with and without GDM. Multivariate analysis showed that placental weight was significantly associated with APOs (p < 0.005), with a cut-off value of 610 grams as demonstrated by the ROC curve.

CONCLUSION

Placental weight ≥ 610 grams and HbA1C ≥ 5.1% were found to be associated with APOs and GDM, respectively, and their evaluation should be part of prenatal care routine.

Factors associated with inflammation in preschool children and women of reproductive age: Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project

Background: In many settings, populations experience recurrent exposure to inflammatory agents that catalyze fluctuations in the concentrations of acute-phase proteins and certain micronutrient biomarkers such as C-reactive protein (CRP), α-1-acid glycoprotein (AGP), ferritin, and retinol. Few data are available on the prevalence and predictors of inflammation in diverse settings.Objective: We aimed to assess the relation between inflammation (CRP concentration >5 mg/L or AGP concentration >1 g/L) and covariates, such as demographics, reported illness, and anthropometric status, in preschool children (PSC) (age range: 6-59 mo) and women of reproductive age (WRA) (age range: 15-49 y).Design: Cross-sectional data from the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project from 29,765 PSC in 16 surveys and 25,731 WRA in 10 surveys were used to model bivariable and multivariable relations.Results: The inflammation prevalence was 6.0-40.2% in PSC and 7.9-29.5% in WRA (elevated CRP) and 21.2-64.3% in PSC and 7.1-26.7% in WRA (elevated AGP). In PSC, inflammation was consistently positively associated with recent fever and malaria but not with other recent illnesses. In multivariable models that were adjusted for age, sex, urban or rural residence, and socioeconomic status, elevated AGP was positively associated with stunting (height-for-age z score <-2) in 7 of 10 surveys. In WRA, elevated CRP was positively associated with obesity [body mass index (in kg/m²) ≥30] in 7 of 9 surveys. Other covariates showed inconsistent patterns of association with inflammation. In a pooled analysis of surveys that measured malaria, stunting was associated with elevated AGP but not CRP in PSC, and obesity was associated with both elevated CRP and AGP in WRA.Conclusions: Recent morbidity and abnormal anthropometric status are consistently associated with inflammation across a range of environments, whereas more commonly collected demographic covariates were not. Because of the challenge of defining a general demographic population or environmental profile that is more likely to experience inflammation, inflammatory markers should be measured in surveys to account for their effects.

Impact of lifestyle intervention for obese women during pregnancy on maternal metabolic and inflammatory markers

BACKGROUND

Offspring of obese mothers have increased risk of developing obesity and related short- and long-term disease. The cause is multifactorial and may partly be explained by the unfavorable intrauterine environment. Intervention during pregnancy leading to a healthier lifestyle among obese may alter this.

OBJECTIVE

To assess the effect of lifestyle intervention on markers of maternal metabolism and inflammation in 'the TOP (Treatment of Obese Pregnant Women) study', a randomized controlled trial.

METHODS

In the TOP-study 425 participants with body mass index ⩾30 kg/m² were randomized to intervention with dietary advices and physical activity assessed by pedometer (PA+D), physical activity assessed by pedometer (PA) or control (C). Of 389 participants completing the study 376 had available blood samples. Serum was analyzed for insulin, c-peptide, lipid profile, leptin, high-sensitivity CRP (hsCRP) and Soluble urokinase Plasminogen Activator Receptor (suPAR), in week 18-20 and 28-30, and simultaneously a 2-h oral glucose-tolerance-test was performed. Diet was assessed in gestational week 11-14 and 36-37 using a validated 360-item Food Frequency Questionnaire.

RESULTS

Median levels of hsCRP in gestational week 28-30 were lower in each of the intervention groups (8.3 mg/l in PA+D group, P=0.03; and 8.8 mg/l in PA group, P=0.02) versus the control group (11.5 mg/l). Obtaining 11 000 steps per day as aimed for resulted in a 21% lower hsCRP compared to non-compliant women. Women reporting high carbohydrate intake had around 30% higher hsCRP concentrations in late gestation than women reporting the lowest intake. There were no differences in lipid profile or any of the metabolic markers in gestational week 28-30 when comparing the intervention and control groups.

CONCLUSIONS

Lifestyle intervention in obese women can reduce hsCRP representing a marker of inflammation during pregnancy. The effect may partly be mediated by more physical activity and partly by changes in intake of carbohydrates and the glycaemic load.

Maternal Circulating Lipid Profile during Early Pregnancy: Racial/Ethnic Differences and Association with Spontaneous Preterm Delivery

Prior reports on the association between altered maternal serum lipid levels with preterm delivery are inconsistent. Ethnic differences in serum lipids during pregnancy and their relation to preterm delivery have not been studied. We examined the relationships of six maternal lipids during early pregnancy with the risk of spontaneous preterm delivery (SPTD). The design represents a case-control study nested within a large prospective, multiethnic cohort of young, generally healthy pregnant women. SPTD cases (n = 183) and controls who delivered at term (n = 376) were included. SPTD is defined as delivery at <37 completed weeks of gestation without indicated conditions. We found that African-American women had significantly increased levels of high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A1 (apoA1), and lower triglyceride (TG) and apolipoprotein B (apoB) levels compared to Hispanic and non-Hispanic Caucasians combined. Elevated HDL-C and apoA1 concentrations were significantly associated with an increased odds of SPTD after controlling for potential confounding factors. The adjusted odds ratio (AOR) was 1.91 (95% confidence interval (CI) 1.15, 3.20) for the highest quartile of HDL-C relative to the lowest quartile, and for apoA1 the AOR was 1.94 (95% CI 1.16, 3.24). When controlling for ethnicity, the results remained comparable. These data suggest that pregnant African-American women had a more favorable lipid profile suggestive of a reduction in cardiovascular risk. Despite this, increased HDL-C and apoA1 were both found to be associated with SPTD.

Maternal diet, gestational weight gain, and inflammatory markers during pregnancy

OBJECTIVE

To examine the associations of gestational weight gain (GWG) and diet with low-grade inflammation in pregnancy.

METHODS

A cross-sectional analysis of 671 pregnant women was performed, and diet was assessed in gestational week 30. GWG was recorded in weeks 30 and ∼37 (difference between the weight recorded at these time points and pre-pregnancy weight). Markers of inflammation, high-sensitivity C-reactive protein (hsCRP), serum amyloid A (SAA), interleukin (IL)-6, IL-8, IL-1β, and tumor necrosis factor-α were quantified in serum from week 30.

RESULTS

After adjusting for age, pre-pregnancy BMI, parity, smoking status, and education, each 1 kg increase in GWG was associated with 3% (95% CI: 1-5) higher hsCRP and 3% (95% CI: 1-4) higher SAA concentrations, which corresponded to ∼18% to 25% increase in these biomarkers among those with excessive weight gain. GWG was inversely associated with IL-8 while no associations were found for the other inflammatory markers. With respect to diet, women in the highest compared with lowest quintile of protein intake had 26% (95% CI: 3-54) higher hsCRP concentrations. This increase appeared to be driven by intake of animal protein. A similar pattern was observed for SAA.

CONCLUSIONS

Excessive GWG, as well as high intake of animal protein, was associated with higher concentrations of inflammatory factors.

Prenatal Exposure to Nitrosatable Drugs, Dietary Intake of Nitrites, and Preterm Birth

Prenatal exposure to nitrosatable drugs, including secondary or tertiary amines, has been associated with preterm birth. Associations may be accentuated by higher intakes of dietary nitrites because of the increased formation of N-nitroso compounds. Using data from mothers of babies without major birth defects (controls) from the National Birth Defects Prevention Study, we examined the relationship between nitrosatable drug exposure in conjunction with dietary nitrite intake and preterm birth among 496 mothers of preterm infants and 5,398 mothers with full-term deliveries in 1997-2005. A protective association was observed with a high intake of plant nitrites (adjusted hazard ratio (AHR) = 0.72, 95% confidence interval (CI): 0.53, 0.97). Secondary amines in conjunction with high nitrite intake were associated with preterm birth during the first (AHR = 1.84, 95% CI: 1.14, 2.98), second (AHR = 1.89, 95% CI: 1.17, 3.07), and third (AHR = 2.00, 95% CI: 1.22, 3.29) trimesters. The adjusted hazard ratios for tertiary amine use in the third trimester by increasing tertiles of nitrite intake were 0.67 (95% CI: 0.35, 1.31), 1.25 (95% CI: 0.71, 2.19), and 2.02 (95% CI: 1.17, 3.49). Prenatal exposure to nitrosatable drugs, particularly secondary and tertiary amines, in conjunction with higher levels of dietary nitrite intake may increase the risk of preterm birth.

Dietary Inflammatory Potential during Pregnancy Is Associated with Lower Fetal Growth and Breastfeeding Failure: Results from Project Viva

BACKGROUND

Inflammation during pregnancy has been linked to adverse maternal and infant outcomes. There is limited information available on the contribution of maternal diet to systemic inflammation and pregnancy health.

OBJECTIVE

The objective of this study was to examine associations of maternal prenatal dietary inflammatory index (DII), a composite measure of the inflammatory potential of diet, with markers of maternal systemic inflammation and pregnancy outcomes.

METHODS

We studied 1808 mother-child pairs from Project Viva, a pre-birth cohort study in Massachusetts. We calculated the DII from first- and second-trimester food-frequency questionnaires by standardizing the dietary intakes of participants to global means, which were multiplied by the inflammatory effect score and summed. We examined associations of DII with maternal plasma C-reactive protein and white blood cell count in the second trimester and the following perinatal outcomes: gestational diabetes, preeclampsia, length of gestation, fetal growth, mode of delivery, and duration of breastfeeding. We used multivariable linear and logistic regression models to analyze the strength of these associations.

RESULTS

Maternal age was (mean ± SD) 32.2 ± 5.0 y, prepregnancy body mass index (BMI; in kg/m(2)) was 24.9 ± 5.2, and DII was -2.56 ± 1.42 units with a range of -5.4 to 3.7. DII was positively correlated with prepregnancy BMI (Pearson'sr= 0.13,P< 0.0001). Higher DII scores, reflecting more proinflammatory dietary potential, were associated with higher second-trimester plasma CRP (β: 0.08 mg/L per 1-unit increase in maternal DII; 95% CI: 0.02, 0.14) and lower birth weight for gestational agezscore in infants born to obese mothers (β: -0.10zscore per 1-unit increase in maternal DII; 95% CI: -0.18, -0.02). Higher DII scores were associated with lower odds of breastfeeding for at least 1 mo (OR = 0.85; 95% CI: 0.74, 0.98).

CONCLUSION

A proinflammatory diet during pregnancy is associated with maternal systemic inflammation and may be associated with impaired fetal growth and breastfeeding failure.

Spontaneous Preterm Delivery, Particularly with Reduced Fetal Growth, is Associated with DNA Hypomethylation of Tumor Related Genes

Background

Preterm delivery and sub-optimal fetal growth are associated with each other and affect both mother and infant. Our aim was to determine (i) whether there are detectable differences in DNA methylation between early and late gestation and (ii) whether changes in DNA methylation from entry are associated with spontaneous preterm delivery with and without reduced fetal growth.

Methods

We conducted a case-control study nested within a large prospective cohort. Gene specific methylation was measured by Methyl-Profiler PCR Array in a Human Breast Cancer Signature Panel of 24 genes from maternal peripheral leukocytes genomic DNA at entry and 3^rd trimester (sampled at 16 and 30 weeks of gestation, respectively). Clonal bisulfite DNA sequencing was performed to confirm the changes in selected genes (CYP1B1, GADD45A and CXCL12). Multivariable analysis was used for data analysis.

Results

There was significantly decrease in DNA methylation in 15 of 24 genes during the 3^rd trimester in cases of spontaneous preterm delivery (n=23) as compared to the controls (n=19) (p<0.05–p<0.01 for each gene). Similar results were observed by bisulfite sequencing for 3 genes. The change in DNA methylation between late and early gestation was significantly different in cases (overall decrease in methylation was −4.0 ± 1.5%) compared to the controls (overall increase in methylation was 12.6 ± 2.19%, p<0.0001). A graded pattern of DNA methylation was observed in 15 genes. Cases who delivered preterm with reduced fetal growth had the lowest level of methylation, cases delivering preterm without reduced fetal growth were next and term controls were highest in methylation (p for trend <0.05 to p<0.01 for each gene). Cases of preterm delivery also had significantly lower dietary choline intake.

Conclusions

These data suggest that epigenetic modification is associated with an increased risk of spontaneous preterm delivery, spontaneous preterm delivery with reduced fetal growth in particular.

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.

C-reactive protein and later preeclampsia: systematic review and meta-analysis taking into account the weight status

OBJECTIVES

This study aims to determine whether high C-reactive protein (CRP) concentration during pregnancy is associated with later preeclampsia and whether weight status (BMI) is a potential modifier of the relation between CRP and preeclampsia.

METHODS

Twenty-three studies were included in a systematic literature review and a subset of 18 in a meta-analysis. Weighted mean difference (WMD) [with their 95% confidence intervals (CI)] of CRP in preeclampsia and control groups was the estimator. A quality assessment was carried out using a scale specifically developed for this study. Meta-regression with estimates for study characteristics and inter-arm differences and sensitivity and subgroup analysis was employed. Statistical heterogeneity was investigated using I(2) statistic.

RESULTS

The pooled estimated CRP between 727 women, who developed preeclampsia and 3538 controls was 2.30 mg/l (95% CI: 1.27-3.34). The heterogeneity among studies was high (I(2) = 92.8). The WMD was found to be lower in studies comprising preeclampsia and control groups with similar BMI [WMD = 0.85 (95% CI: 0.10-1.61); I(2) = 25.3%] compared with studies among which BMI was significantly elevated in the preeclampsia group [2.01 (95% CI: 1.23-2.78); I(2) = 0.0%], which may explain the high heterogeneity of pooled data. Meta-regression results confirmed that difference in BMI between groups modifies the association of CRP and preeclampsia. High quality studies represented 30%.

CONCLUSION

The pooled WMD suggest that women with higher levels of CRP may have an increased risk of developing preeclampsia. This association seems to be modified by confounders, such as BMI. Further studies of high methodological quality are needed.