Aspirin for the prevention of preeclampsia in women with abnormal uterine artery Doppler: a meta-analysis

A Review of Roles of Uterine Artery Doppler in Pregnancy Complications

The invasion of trophoblasts into the uterine decidua and decidual vessels is critical for the formation of placenta. The defects of placentation are related to the etiologies of preeclampsia (PE), fetal growth restriction (FGR), and small-for-gestational age (SGA) neonates. It is possible to predict significant vascular events during pregnancy through uterine artery Doppler (UAD). From the implantation stage to the end of pregnancy, detecting changes in uterine and placental blood vessels can provide a favorable diagnostic instrument for pregnancy complications. This review aims to collect literature about the roles of UAD in pregnancy complications. We consider all relevant articles in English from January 1, 1983 to October 30, 2021. Predicting pregnancy complications in advance allows practitioners to carry out timely interventions to avoid or lessen the harm to mothers and neonates. Administering low-dose aspirin daily before 16 weeks of pregnancy can significantly reduce the incidence of pregnancy complications. From early pregnancy to late pregnancy, UAD can combine with other maternal factors, biochemical indicators, and fetal measurement data to identify high-risk population. The identification of high-risk groups can also lessen maternal mortality. Besides, through moderate risk stratification, stringent monitoring for high-risk pregnant women can be implemented, decreasing the incidence of adversities.

Antiplatelet agents for preventing pre-eclampsia and its complications

BACKGROUND

Pre-eclampsia is associated with deficient intravascular production of prostacyclin, a vasodilator, and excessive production of thromboxane, a vasoconstrictor and stimulant of platelet aggregation. These observations led to the hypotheses that antiplatelet agents, low-dose aspirin in particular, might prevent or delay development of pre-eclampsia.

OBJECTIVES

To assess the effectiveness and safety of antiplatelet agents, such as aspirin and dipyridamole, when given to women at risk of developing pre-eclampsia.

SEARCH METHODS

For this update, we searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (30 March 2018), and reference lists of retrieved studies. We updated the search in September 2019 and added the results to the awaiting classification section of the review.

SELECTION CRITERIA

All randomised trials comparing antiplatelet agents with either placebo or no antiplatelet agent were included. Studies only published in abstract format were eligible for inclusion if sufficient information was available. We would have included cluster-randomised trials in the analyses along with individually-randomised trials, if any had been identified in our search strategy. Quasi-random studies were excluded. Participants were pregnant women at risk of developing pre-eclampsia. Interventions were administration of an antiplatelet agent (such as low-dose aspirin or dipyridamole), comparisons were either placebo or no antiplatelet.

DATA COLLECTION AND ANALYSIS

Two review authors assessed trials for inclusion and extracted data independently. For binary outcomes, we calculated risk ratio (RR) and its 95% confidence interval (CI), on an intention-to-treat basis. For this update we incorporated individual participant data (IPD) from trials with this available, alongside aggregate data (AD) from trials where it was not, in order to enable reliable subgroup analyses and inclusion of two key new outcomes. We assessed risk of bias for included studies and created a 'Summary of findings' table using GRADE.

MAIN RESULTS

Seventy-seven trials (40,249 women, and their babies) were included, although three trials (relating to 233 women) did not contribute data to the meta-analysis. Nine of the trials contributing data were large (> 1000 women recruited), accounting for 80% of women recruited. Although the trials took place in a wide range of countries, all of the nine large trials involved only women in high-income and/or upper middle-income countries. IPD were available for 36 trials (34,514 women), including all but one of the large trials. Low-dose aspirin alone was the intervention in all the large trials, and most trials overall. Dose in the large trials was 50 mg (1 trial, 1106 women), 60 mg (5 trials, 22,322 women), 75mg (1 trial, 3697 women) 100 mg (1 trial, 3294 women) and 150 mg (1 trial, 1776 women). Most studies were either low risk of bias or unclear risk of bias; and the large trials were all low risk of bas. Antiplatelet agents versus placebo/no treatment The use of antiplatelet agents reduced the risk of proteinuric pre-eclampsia by 18% (36,716 women, 60 trials, RR 0.82, 95% CI 0.77 to 0.88; high-quality evidence), number needed to treat for one women to benefit (NNTB) 61 (95% CI 45 to 92). There was a small (9%) reduction in the RR for preterm birth <37 weeks (35,212 women, 47 trials; RR 0.91, 95% CI 0.87 to 0.95, high-quality evidence), NNTB 61 (95% CI 42 to 114), and a 14% reduction infetal deaths, neonatal deaths or death before hospital discharge (35,391 babies, 52 trials; RR 0.85, 95% CI 0.76 to 0.95; high-quality evidence), NNTB 197 (95% CI 115 to 681). Antiplatelet agents slightly reduced the risk of small-for-gestational age babies (35,761 babies, 50 trials; RR 0.84, 95% CI 0.76 to 0.92; high-quality evidence), NNTB 146 (95% CI 90 to 386), and pregnancies with serious adverse outcome (a composite outcome including maternal death, baby death, pre-eclampsia, small-for-gestational age, and preterm birth) (RR 0.90, 95% CI 0.85 to 0.96; 17,382 women; 13 trials, high-quality evidence), NNTB 54 (95% CI 34 to 132). Antiplatelet agents probably slightly increase postpartum haemorrhage > 500 mL (23,769 women, 19 trials; RR 1.06, 95% CI 1.00 to 1.12; moderate-quality evidence due to clinical heterogeneity), and they probably marginally increase the risk of placental abruption, although for this outcome the evidence was downgraded due to a wide confidence interval including the possibility of no effect (30,775 women; 29 trials; RR 1.21, 95% CI 0.95 to 1.54; moderate-quality evidence). Data from two large trials which assessed children at aged 18 months (including results from over 5000 children), did not identify clear differences in development between the two groups.

AUTHORS' CONCLUSIONS

Administering low-dose aspirin to pregnant women led to small-to-moderate benefits, including reductions in pre-eclampsia (16 fewer per 1000 women treated), preterm birth (16 fewer per 1000 treated), the baby being born small-for-gestational age (seven fewer per 1000 treated) and fetal or neonatal death (five fewer per 1000 treated). Overall, administering antiplatelet agents to 1000 women led to 20 fewer pregnancies with serious adverse outcomes. The quality of evidence for all these outcomes was high. Aspirin probably slightly increased the risk of postpartum haemorrhage of more than 500 mL, however, the quality of evidence for this outcome was downgraded to moderate, due to concerns of clinical heterogeneity in measurements of blood loss. Antiplatelet agents probably marginally increase placental abruption, but the quality of the evidence was downgraded to moderate due to low event numbers and thus wide 95% CI. Overall, antiplatelet agents improved outcomes, and at these doses appear to be safe. Identifying women who are most likely to respond to low-dose aspirin would improve targeting of treatment. As almost all the women in this review were recruited to the trials after 12 weeks' gestation, it is unclear whether starting treatment before 12 weeks' would have additional benefits without any increase in adverse effects. While there was some indication that higher doses of aspirin would be more effective, further studies would be warranted to examine this.

Treatment of high risk pregnancies

Introduction: The efficacy of a therapy with certoparin; also in combination with aspirin and prednisolone; in high-risk pregnancies has been examined prospectively.

Method: Data of 616 pregnancies have been analyzed. 238 patients injected Mono Embolex 3000; 239 patients Mono Embolex 8000 only. 62 patients injected Mono Embolex 8000 and took aspirin 50–100 mg daily; 60 Mono Embolex 3000 and aspirin 50–100 mg daily. 30 patients took aspirin 50–100 mg; prednisolone 2.5–5 mg and 17 injected mono Embolex 8000; 13 Mono Embolex 3000 daily from the start of their pregnancy. The target variable was the life birth rate.

When given aspirin the HPA-status of the partner is measured if the pregnant woman is negative for HPA 1a or 5b. In HPA-negative mothers and HPA-positive fathers a test for HPA-antibodies is performed posterior week 16.

Result: Applied early; a mean life birth rate of 95 % has been achieved in the monotherapy with Mono Embolex. Where heparin and aspirin were applied before pregnancy week 17 a life birth rate of 100 % was achieved. In patientswith a combination of aspirin and prednisolone a life birth rate of 87 % was achieved. Considering the life birth rate the status of thrombophilia gene-polymorphisms is irrelevant. The HPA-status was examined in 139 patients. In one of the HPA 5a-negative and 3 of the HPA 5b-negative women an immunization occurred but the platelet count of the fetus was not decreased. 3.3 % showed local allergic reaction and 0.5 % slight bleeding.

Conclusion: Certoparin, aspirin and prednisolone are safe drugs to increase life birth rate.

Preeclampsia in high risk women is characterized by risk group-specific abnormalities in serum biomarkers

OBJECTIVE

To determine if early pregnancy serum biomarkers in high-risk women who develop preeclampsia vary according to risk factor.

STUDY DESIGN

We performed a secondary analysis of the Maternal-Fetal Medicine Units Network randomized controlled trial of low-dose aspirin for the prevention of preeclampsia in high-risk women. Serum biomarker levels at enrollment (before initiation of aspirin or placebo) were compared between women who did and did not develop preeclampsia, both for the group as a whole and within each of 4 high-risk groups (insulin-dependent diabetes, hypertension, multiple gestation, and previous preeclampsia) using a regression model adjusting for gestational age at collection and prepregnancy body mass index.

RESULTS

1258 women were included (233 with insulin-dependent diabetes, 387 with chronic hypertension, 315 with a multiple gestation, 323 with previous preeclampsia). Multiple early pregnancy serum biomarkers differed between women who did and did not develop preeclampsia. Each high-risk group had a unique and largely nonoverlapping pattern of biomarker abnormality. Differences between those who did and did not develop preeclampsia were noted in vascular cell adhesion molecule in the diabetes group; human chorionic gonadotropin, soluble tumor necrosis factor receptor-2, tumor necrosis factor-alpha, selectin and angiogenin in the chronic hypertension group; interleukin-6, placental growth factor, soluble fms-like tyrosine kinase plus endoglin to placental growth factor ratio in the multiple gestation group; and angiogenin in the previous preeclampsia group.

CONCLUSION

Patterns of serum biomarkers vary by high-risk group. These data support the hypothesis that multiple pathogenic pathways lead to the disease recognized clinically as preeclampsia.

Aspirin and preeclampsia prevention in patients with abnormal uterine artery blood flow

Background:

Preeclampsia is one of the leading causes of maternal mortality and morbidity. Its prevalence varies between 10-25% among high-risk pregnant patients.

Objectives:

The aim of this study was to determine whether treatment with acetylsalicylic acid (ASA) reduces the incidence of preeclampsia among pregnant women with abnormal uterine artery flow.

Patients and Methods:

In this double-blind, placebo controlled trial, 80 high-risk pregnant women with preeclampsia, who had abnormal findings on Doppler ultrasonography at 12-16 weeks of pregnancy (unilateral notch with RI ≥ 0.65 or bilateral notch with RI ≥ 0.55), were randomly divided into two groups; the intervention group was treated with ASA tablet 80 mg, one tablet per day, and the control group was given placebo. Then patients were followed until the end of their pregnancy period, and pregnancy outcomes, including development of preeclampsia, the intrauterine growth retardation (IUGR), prematurity, type of delivery, birth weight, and Apgar score at one and five minutes were assessed. Data were analyzed using the student's t-test, chi-square or Fisher's exact test, and multivariate logistic regression. P values less than 0.05 were considered statistically significant.

Results:

There were no significant differences between the two groups in terms of baseline characteristics. There was a significant difference between the ASA and placebo groups in the incidence of preeclampsia (2.5% versus 22.5%), adjusting for the neonatal and maternal covariates.

Conclusions:

ASA prophylaxis can be used for prevention of preeclampsia in high-risk patients with abnormal uterine artery.

Aspirin plus calcium supplementation to prevent superimposed preeclampsia: a randomized trial

Preeclampsia is an important cause of maternal and perinatal morbidity and mortality. Previous studies have tested calcium supplementation and aspirin separately to reduce the incidence of preeclampsia but not the effects of combined supplementation. The objective of this study was to investigate the effectiveness of aspirin combined with calcium supplementation to prevent preeclampsia in women with chronic hypertension. A double-blind, placebo-controlled randomized clinical trial was carried out at the antenatal clinic of a large university hospital in São Paulo, SP, Brazil. A total of 49 women with chronic hypertension and abnormal uterine artery Doppler at 20-27 weeks gestation were randomly assigned to receive placebo (N = 26) or 100 mg aspirin plus 2 g calcium (N = 23) daily until delivery. The main outcome of this pilot study was development of superimposed preeclampsia. Secondary outcomes were fetal growth restriction and preterm birth. The rate of superimposed preeclampsia was 28.6% lower among women receiving aspirin plus calcium than in the placebo group (52.2 vs 73.1%, respectively, P=0.112). The rate of fetal growth restriction was reduced by 80.8% in the supplemented group (25 vs 4.8% in the placebo vs supplemented groups, respectively; P=0.073). The rate of preterm birth was 33.3% in both groups. The combined supplementation of aspirin and calcium starting at 20-27 weeks of gestation produced a nonsignificant decrease in the incidence of superimposed preeclampsia and fetal growth restriction in hypertensive women with abnormal uterine artery Doppler.

Individual risk assessment of adverse pregnancy outcome by multivariate regression analysis may serve as basis for drug intervention studies: retrospective analysis of 426 high-risk patients including ethical aspects

OBJECTIVE

To identify patients at very high risk for adverse pregnancy outcome (APO) at the 20- to 23-week scan and to assess the effectiveness of Aspirin (ASS) and low molecular weight heparin (LMWH) starting after this examination.

PATIENTS AND METHODS

By applying an algorithm based on multivariate logistic regression analysis using the parameters maternal age, parity, body mass index (BMI), mean pulsatility index of both uterine arteries (meanPI), presence of uni- or bilateral notch, and depth of notch (mean notch index (meanNI), we retrospectively calculated the individual risk for APO of 21,302 singleton pregnancies. We isolated a subgroup of 426 patients with the highest calculated probability for APO (cpAPO > 27.8 %). 147 had been treated with ASS; 73 with LMWH, 15 patients with a combination of ASS and LMWH, and 191 patients had not received anticoagulants.

RESULTS

Administration of ASS starting after 20 gestational weeks in comparison to non-treated patients significantly reduced the frequency of intrauterine/neonatal death (IUD/NND), preeclampsia <33 weeks (PE < 33), and preterm delivery <33 weeks (PD < 33), while the frequency of IUGR showed a tendency to be elevated (P = 0.061). The subgroup of high-risk patients treated with LMWH was characterised by a higher a priori risk for APO and showed no significant reduction of any form of APO but an increased frequency of PE.

CONCLUSION

Individual assessment of risk for APO by applying a simple algorithm based on biometrical/biographical as well as sonographic parameters may serve as basis for drug intervention studies. The administration of ASS in high-risk patients starting after 20 gestational weeks reduced the frequency of most of the severe forms of adverse pregnancy outcome in high-risk patients. A complication-reducing effect of LMWH starting after 20 weeks of gestation in patients could not be proven. From an ethical point of view, it may not be justified any more to preclude high-risk patients from administration of ASS or to perform studies of ASS against placebo.

Prevention of preeclampsia

Preeclampsia (PE) affects around 2–5% of pregnant women. It is a major cause of maternal and perinatal morbidity and mortality. In an attempt to prevent preeclampsia, many strategies based on antenatal care, change in lifestyle, nutritional supplementation, and drugs have been studied. The aim of this paper is to review recent evidence about primary and secondary prevention of preeclampsia.

Effects of calcium, magnesium, low-dose aspirin and low-molecular-weight heparin on the release of PP13 from placental explants

BACKGROUND

Preeclampsia is one of the leading causes for maternal and fetal morbidity. Attempts to prevent preeclampsia have already been made using low-dose aspirin, low-molecular-weight heparin (LMWH), and calcium supplementation. Magnesium sulphate is used at the time of disease to prevent eclampsia. Here we investigated the effect of these agents on PP13 release from placental explants.

METHODS

Placentas harvested after C-section of term or preterm control and preeclampsia cases or first trimester terminations were used to obtain explants. Explants were incubated for 24h with/without respective agents, harvested, weighed and subjected to PP13 determination in the culture medium and the explant. LDH was used to determine viability. Dose response curves were obtained for each drug. P < 0.05 was considered significant.

RESULTS

Exposure to magnesium (0.7-7g/day) slightly decreased PP13 release from controls, and slightly increased it in preeclampsia and first trimester termination. Calcium (0. 3-6g/day) showed a tendency to decrease the release in control and preeclampsia, whereas in first trimester release was increased in a bell-shaped manner. Aspirin (0-250 mg/day) tended to decrease the release in controls but increased it in a bell-shaped manner in first trimester and preeclampsia. LMWH showed no effect from 0 to 80 mg/day in controls but tended to decrease PP13 release in preeclampsia and first trimester.

CONCLUSION

This data might point to a beneficial effect of aspirin and calcium supplementation in the first trimester of pregnancy and aspirin at the time of disease, although the interaction with the maternal system still needs to be elucidated.

Risk factors and mediators of the vascular dysfunction associated with hypertension in pregnancy

Normal pregnancy is associated with significant hemodynamic changes and vasodilation in the uterine and systemic circulation in order to meet the metabolic demands of the mother and developing fetus. Hypertension in pregnancy (HTN-Preg) and preeclampsia (PE) are major complications and life-threatening conditions to both the mother and fetus. PE is precipitated by various genetic, dietary and environmental factors. Although the initiating events of PE are unclear, inadequate invasion of cytotrophoblasts into the uterine artery is thought to reduce uteroplacental perfusion pressure and lead to placental ischemia/hypoxia. Placental hypoxia induces the release of biologically active factors such as growth factor inhibitors, anti-angiogenic proteins, inflammatory cytokines, reactive oxygen species, hypoxia-inducible factors, and antibodies to vascular angiotensin II receptor. These bioactive factors affect the production/activity of various vascular mediators in the endothelium, smooth muscle and extracellular matrix, leading to severe vasoconstriction and HTN. As an endothelial cell disorder, PE is associated with decreased vasodilator mediators such as nitric oxide, prostacyclin and hyperpolarizing factor and increased vasoconstrictor mediators such as endothelin, angiotensin II and thromboxane A(2). PE also involves enhanced mechanisms of vascular smooth muscle contraction including intracellular free Ca(2+) concentration ([Ca(2+)](i)), and [Ca(2+)](i) sensitization pathways such as protein kinase C, Rho-kinase and mitogen-activated protein kinase. Changes in extracellular matrix composition and matrix metalloproteases activity also promote vascular remodeling and further vasoconstriction in the uterine and systemic circulation. Characterization of the predisposing risk factors, the biologically active factors, and the vascular mediators associated with PE holds the promise for early detection, and should help design specific genetic and pharmacological tools for the management of the vascular dysfunction associated with HTN-Preg.

Circulating and Vascular Bioactive Factors during Hypertension in Pregnancy

Normal pregnancy is associated with significant vascular remodeling in the uterine and systemic circulation in order to meet the metabolic demands of the mother and developing fetus. The pregnancy-associated vascular changes are largely due to alterations in the amount/activity of vascular mediators released from the endothelium, vascular smooth muscle and extracellular matrix. The endothelium releases vasodilator substances such as nitric oxide, prostacyclin and hyperpolarizing factor as well as vasoconstrictor factors such as endothelin, angiotensin II and thromboxane A(2). Vascular smooth muscle contraction is mediated by intracellular free Ca(2+) concentration ([Ca(2+)](i)), and [Ca(2+)](i) sensitization pathways such as protein kinase C, Rho-kinase and mitogen-activated protein kinase. Extracellular matrix and vascular remodeling are regulated by matrix metalloproteases. Hypertension in pregnancy and preeclampsia are major complications and life threatening conditions to both the mother and fetus, precipitated by various genetic, dietary and environmental factors. The initiating mechanism of preeclampsia and hypertension in pregnancy is unclear; however, most studies have implicated inadequate invasion of cytotrophoblasts into the uterine artery, leading to reduction in the uteroplacental perfusion pressure and placental ischemia/hypoxia. This placental hypoxic state is thought to induce the release of several circulating bioactive factors such as growth factor inhibitors, anti-angiogenic proteins, inflammatory cytokines, reactive oxygen species, hypoxia-inducible factors, and vascular receptor antibodies. Increases in the plasma levels and vascular content of these factors during pregnancy could cause an imbalance in the vascular mediators released from the endothelium, smooth muscle and extracellular matrix, and lead to severe vasoconstriction and hypertension. This review will discuss the interactions between the various circulating bioactive factors and the vascular mediators released during hypertension in pregnancy, and provide an insight into the current and future approaches in the management of preeclampsia.

Tests for predicting complications of pre-eclampsia: a protocol for systematic reviews

BACKGROUND

Pre-eclampsia is associated with several complications. Early prediction of complications and timely management is needed for clinical care of these patients to avert fetal and maternal mortality and morbidity. There is a need to identify best testing strategies in pre eclampsia to identify the women at increased risk of complications. We aim to determine the accuracy of various tests to predict complications of pre-eclampsia by systematic quantitative reviews.

METHOD

We performed extensive search in MEDLINE (1951-2004), EMBASE (1974-2004) and also will also include manual searches of bibliographies of primary and review articles. An initial search has revealed 19500 citations. Two reviewers will independently select studies and extract data on study characteristics, quality and accuracy. Accuracy data will be used to construct 2 x 2 tables. Data synthesis will involve assessment for heterogeneity and appropriately pooling of results to produce summary Receiver Operating Characteristics (ROC) curve and summary likelihood ratios.

DISCUSSION

This review will generate predictive information and integrate that with therapeutic effectiveness to determine the absolute benefit and harm of available therapy in reducing complications in women with pre-eclampsia.

Obesity and pregnancy

Obesity is reaching pandemic proportions worldwide. It is increasingly being recognised as a risk factor during pregnancy. Women should ideally be counselled preconceptionally about the increased risks and encouraged to lose weight actively, some may be candidates for bariatric surgery. Maternal risks include gestational diabetes, hypertension and pre-eclampsia, increased incidence of operative delivery, postpartum haemorrhage, anaesthetic risks as well as infective and thrombo-embolic complications while fetal risks include miscarriage, neural-tube defects, macrosomia and stillbirth. Obstetric units should institute appropriate guidelines for the management of pregnancy in this 'high-risk' group of women.

Use of uterine artery Doppler ultrasonography to predict pre-eclampsia and intrauterine growth restriction: a systematic review and bivariable meta-analysis

BACKGROUND

Alterations in waveforms in the uterine artery are associated with the development of pre-eclampsia and intrauterine growth restriction. We investigated the predictive accuracy of all uterine artery Doppler indices for both conditions in the first and second trimesters.

METHODS

We identified relevant studies through searches of MEDLINE, EMBASE, the Cochrane Library and Medion databases (all records to April 2006) and by checking bibliographies of identified studies and consulting with experts. Four of us independently selected studies, extracted data and assessed study validity. We performed a bivariable meta-analysis of sensitivity and specificity and calculated likelihood ratios.

RESULTS

We identified 74 studies of pre-eclampsia (total 79,547 patients) and 61 studies of intrauterine growth restriction (total 41 131 patients). Uterine artery Doppler ultrasonography provided a more accurate prediction when performed in the second trimester than in the first-trimester. Most Doppler indices had poor predictive characteristics, but this varied with patient risk and outcome severity. An increased pulsatility index with notching was the best predictor of pre-eclampsia (positive likelihood ratio 21.0 among high-risk patients and 7.5 among low-risk patients). It was also the best predictor of overall (positive likelihood ratio 9.1) and severe (positive likelihood ratio 14.6) intrauterine growth restriction among low-risk patients.

INTERPRETATION

Abnormal uterine artery waveforms are a better predictor of pre-eclampsia than of intrauterine growth restriction. A pulsatility index, alone or combined with notching, is the most predictive Doppler index. These indices should be used in clinical practice. Future research should also concentrate on combining uterine artery Doppler ultrasonography with other tests.

Accuracy of fibronectin tests for the prediction of pre-eclampsia: a systematic review

The purpose of this study was to review systematically all studies that assessed the accuracy of maternal plasma fibronectin as a serum marker for early prediction of pre-eclampsia. We therefore assessed studies that reported on fibronectin as serum marker for pre-eclampsia before the 25th gestational week. For the selected studies, sensitivity and specificity were calculated and plotted in ROC-space. We included 12 studies, of which only 5 studies reported sufficient data to calculate accuracy estimates, such as sensitivity and specificity. These five studies reported on 573 pregnant women of whom 109 developed pre-eclampsia. At a sensitivity of at least 50%, specificities ranged between 72 and 96% for cellular fibronectin. For total fibronectin, these numbers were 42-94%. Fibronectin seems to be a promising marker for the prediction of pre-eclampsia, however, further studies are needed to determine whether the accuracy of this test is sufficient to be clinically relevant.

A review of the methodological features of systematic reviews in maternal medicine

BACKGROUND

In maternal medicine, research evidence is scattered making it difficult to access information for clinical decision making. Systematic reviews of good methodological quality are essential to provide valid inferences and to produce usable evidence summaries to guide management. This review assesses the methodological features of existing systematic reviews in maternal medicine, comparing Cochrane and non-Cochrane reviews in maternal medicine.

METHODS

Medline, Embase, Database of Reviews of Effectiveness (DARE) and Cochrane Database of Systematic Reviews (CDSR) were searched for relevant reviews published between 2001 and 2006. We selected those reviews in which a minimum of two databases were searched and the primary outcome was related to the maternal condition. The selected reviews were assessed for information on framing of question, literature search and methods of review.

RESULTS

Out of 2846 citations, 68 reviews were selected. Among these, 39 (57%) were Cochrane reviews. Most of the reviews (50/68, 74%) evaluated therapeutic interventions. Overall, 54/68 (79%) addressed a focussed question. Although 64/68 (94%) reviews had a detailed search description, only 17/68 (25%) searched without language restriction. 32/68 (47%) attempted to include unpublished data and 11/68 (16%) assessed for the risk of missing studies quantitatively. The reviews had deficiencies in the assessment of validity of studies and exploration for heterogeneity. When compared to Cochrane reviews, other reviews were significantly inferior in specifying questions (OR 20.3, 95% CI 1.1-381.3, p = 0.04), framing focussed questions (OR 30.9, 95% CI 3.7- 256.2, p = 0.001), use of unpublished data (OR 5.6, 95% CI 1.9-16.4, p = 0.002), assessment for heterogeneity (OR 38.1, 95%CI 2.1, 688.2, p = 0.01) and use of meta-analyses (OR 3.7, 95% CI 1.3-10.8, p = 0.02).

CONCLUSION

This study identifies areas which have a strong influence on maternal morbidity and mortality but lack good quality systematic reviews. Overall quality of the existing systematic reviews was variable. Cochrane reviews were of better quality as compared to other reviews. There is a need for good quality systematic reviews to inform practice in maternal medicine.

Pregnancy and its management in the Philadelphia negative myeloproliferative diseases

The myeloproliferative diseases (MPDs) present several therapeutic challenges in patients of childbearing potential. The most extensive literature exists for patients with essential thrombocythaemia, with over 200 pregnancies reported in retrospective case series. Yet there is conflicting data in relation to predicting pregnancy outcome and optimal management strategy. Pregnancy is less frequently reported for polycythaemia vera and myelofibrosis. There is a need for collaboration to further our knowledge in this field. Here, the literature is reviewed in detail and experience of different therapeutic strategies in pregnancy discussed. There is increasing understanding about the pathogenesis of placental dysfunction in inherited thrombophilia and antiphospholipid antibody syndrome pregnancy outcomes in these conditions parallel those reported for MPDs. Furthermore several large studies have influenced pregnancy management in these conditions and, whilst not directly applicable to MPDs, this data have potential to inform treatment protocols. This data are reviewed and a personal management strategy for pregnancy in MPD proposed.

Pre-eclampsia

Pre-eclampsia is a major cause of maternal mortality (15-20% in developed countries) and morbidities (acute and long-term), perinatal deaths, preterm birth, and intrauterine growth restriction. Key findings support a causal or pathogenetic model of superficial placentation driven by immune maladaptation, with subsequently reduced concentrations of angiogenic growth factors and increased placental debris in the maternal circulation resulting in a (mainly hypertensive) maternal inflammatory response. The final phenotype, maternal pre-eclamptic syndrome, is further modulated by pre-existing maternal cardiovascular or metabolic fitness. Currently, women at risk are identified on the basis of epidemiological and clinical risk factors, but the diagnostic criteria of pre-eclampsia remain unclear, with no known biomarkers. Treatment is still prenatal care, timely diagnosis, proper management, and timely delivery. Many interventions to lengthen pregnancy (eg, treatment for mild hypertension, plasma-volume expansion, and corticosteroid use) have a poor evidence base. We review findings on the diagnosis, risk factors, and pathogenesis of pre-eclampsia and the present status of its prediction, prevention, and management.

Maternal nonpregnant vascular function correlates with subsequent fetal growth

OBJECTIVE

Evidence is accumulating that fetal growth is influenced by preexisting maternal disorder(s) hampering endothelial function. We tested the hypothesis that in nonpregnant normotensive, formerly preeclamptic women, vascular function predicts the development of fetal growth restriction.

METHODS

In 60 formerly preeclamptic women, we measured central hemodynamic and vascular and clotting function mid follicular phase during the menstrual cycle. Inclusion for final analysis required besides normotension, a subsequent singleton pregnancy, established within 1 year after the prepregnant evaluation and ongoing beyond 16 weeks' gestation. In the ongoing pregnancy we determined birth weight and birth weight percentile.

RESULTS

Among 60 formerly preeclamptic women, 45 (75%) were normotensive. Thirty-one (69%) participants succeeded in establishing an ongoing pregnancy within 1 year and were included for final analysis. Of the 31 subsequent pregnancies, 8 (26%) were complicated by fetal growth restriction. Prepregnant left and right uterine artery pulsatility index (PI) correlated inversely with carotid artery compliance ( r = 0.57, P = .005, r = 0.62, P = .002) and venous compliance ( r = 0.49, P = .02 and r = 0.45, P = .04, respectively). The latter, in turn, correlates with plasma volume ( r = 0.63, P = .001) and total peripheral vascular resistance index ( r = -0.45, P = .02). Finally, prepregnant left and right uterine artery PI correlated inversely with subsequent achieved fetal growth ( r = -0.68, P < .0001 and r = -0.58, P = .001, respectively).

CONCLUSION

In nonpregnant normotensive, formerly preeclamptic women, an elevated uterine artery PI predisposes to subsequent restriction in fetal growth.

Preeclampsia--abnormal uterine artery Doppler is related to recurrence of symptoms during the next pregnancy

BACKGROUND

Impaired trophoblast invasion is suggested as the main cause of reduced placental perfusion, which results in fetal growth restriction and preeclampsia. Immunological response against the invading tissue has been given as the explanation. Preeclampsia frequently recurs during the next pregnancy. Doppler ultrasound can predict increased vascular impedance in the uteroplacental circulation. Whether signs of increased vascular resistance in pregnancies complicated by preeclampsia are predictive of recurrence during the next pregnancy is unknown.

METHODS AND MATERIAL

Uterine artery Doppler was performed in 570 pregnant women with preeclampsia. Of these, 139 became pregnant again. The uterine artery Doppler results during the first pregnancy were related to symptoms of preeclampsia in the succeeding pregnancy.

RESULTS

Preeclampsia developed again in 43 of the 139 women. Pregnancies with signs of increased uterine artery vascular impedance during the first pregnancy were 3.4 times more likely to develop preeclampsia again (CI 1.58-7.6). Similar results for a small for gestational age newborn were 9.7 (CI 1.1-90).

CONCLUSION

Increased uterine artery vascular impedance in pregnancies complicated by preeclampsia increases the likelihood of recurrence and growth restriction during the next pregnancy. The Doppler information gathered during the first pregnancy might thus select cases for special surveillance and possibly prophylactic anti-platelet treatment in the next pregnancy.

Prediction of Preeclampsia or Intrauterine Growth Restriction by Second Trimester Serum Screening and Uterine Doppler Velocimetry

OBJECTIVE

To assess the performance of screening for preeclampsia and intrauterine growth restriction by combining second trimester maternal serum screening and uterine Doppler ultrasound.

METHODS

A cohort of 2,615 women underwent both maternal serum screening (using human chorionic gonadotropin (hCG) and alpha-fetoprotein (AFP)), and second trimester uterine artery Doppler. The sensitivity, specificity and predictive value of different combinations of both tests were compared.

RESULTS

The mean values for hCG and AFP were significantly higher in women with subsequent preeclampsia (p < 0.0003 and p < 0.03, respectively). Taking into account obstetrical history, hCG and AFP levels, notching on uterine artery Doppler and parity, the adjusted odds ratios were significantly higher for a high level of hCG for preeclampsia, intrauterine growth restriction (IUGR) and pregnancy-induced hypertension. AFP level >1.5 MoM (multiples of the median) was significantly correlated with subsequent IUGR. The presence of a uterine notch was associated with a significantly higher risk of both preeclampsia and IUGR. The combination of an elevated serum level and the presence of a uterine notch had a positive predictive value (PPV) for preeclampsia of 25 and 21% for hCG and AFP, respectively. The combination of a bilateral notch with a low level of hCG or a high level of AFP had a PPV for IUGR of 50 and 43%, respectively. The sensitivity of the different tests ranged from 2 to 40%.

CONCLUSION

The combination of serum markers and abnormal uterine Doppler ultrasound improves the identification of women at risk for subsequent pregnancy complications. These results should encourage care providers to perform a uterine Doppler ultrasound when serum markers are abnormal. However, the sensitivity of these tests is too low to provide an efficient generalized screening.

Perinatal outcome prediction by maternal homocysteine and uterine artery Doppler velocimetry

OBJECTIVES

(a) To evaluate the predictive value of uterine Doppler velocimetry for pregnancy complications, (b) to study the relationship between abnormal uterine Doppler velocimetry and plasma homocysteine, and (c) to determine whether homocysteine measurement improves the predictive value of uterine Doppler screening.

STUDY DESIGN

Prospective study including 94 pregnant women without previous risk factors. Total homocysteine, folate and Vitamin B(12) were analysed. Uterine Doppler velocimetry at weeks 24-25 was performed.

RESULTS

The presence of any uterine Doppler alteration had a sensitivity of 66.7%, and a specificity of 81.2%, in predicting obstetric complications. The likelihood ratio was 3.6. The positive and negative predictive values were 27.3 and 95.8%, respectively. The global efficiency was 83.0%. The addition of hyperhomocysteinemia to Doppler alterations increased the sensitivity from 66.7 to 77.8%.

CONCLUSIONS

The addition of homocysteine determination to uterine Doppler evaluation in the second trimester does not usefully improve its predictive value.

Randomised comparison of uterine artery Doppler and aspirin (100 mg) with placebo in nulliparous women: the Essai Régional Aspirine Mère-Enfant study (Part 2)

OBJECTIVE

To assess the effectiveness of a pre-eclampsia prevention strategy based on routine uterine artery Doppler flow velocity waveform examination during the second trimester of pregnancy, followed by a prescription for 100 mg aspirin in the case of abnormal Doppler findings.

DESIGN

Multicentre randomised controlled trial.

SETTING

Eleven centres in the north of France and one in Belgium.

POPULATION

One thousand and eight hundred and fifty-three nulliparous women recruited between 14 and 20 weeks of gestation.

METHODS

Randomisation either to undergo a uterine Doppler examination between 22 and 24 week of gestation or to take a placebo. Women with abnormal Doppler waveforms received 100 mg of aspirin daily from Doppler examination through 36 weeks.

MAIN OUTCOME MEASURES

Pre-eclampsia was defined as hypertension (> or = 140 and/or 90 mmHg) associated with proteinuria (> or = 0.5 g/L).

RESULTS

One thousand two hundred and fifty-three women (67%) were randomised into the systematic Doppler group and 617 (33%) into the placebo group. Of the 1175 patients in the Doppler group who underwent this examination, 239 (20.3%) had abnormal uterine artery Doppler and received a prescription for aspirin. Despite the aspirin prescription, the frequency of pre-eclampsia did not differ between the systematic Doppler group and the placebo group (28 of 1237 [2.3%] vs 9 of 616 [1.5%]; RR = 1.55, 95% CI 0.7-3.3). Furthermore, the groups did not differ in the frequency of children who were very small for their gestational age (< or =3rd centile) or for perinatal deaths. Compared with patients with normal Doppler findings, those with abnormal Doppler were at high risk of pre-eclampsia (RR = 5.5, 95% CI 2.5-12.2) and of giving birth to a small-for-gestational-age child (RR = 3.6, 95% CI 1.6-8.1).

CONCLUSION

Despite its sensitivity in screening for pre-eclampsia, routine uterine Doppler in the second trimester cannot be recommended for nulliparous patients.