Low dose aspirin in hypertensive pregnant women: effect on pregnancy outcome and prostacyclin-thromboxane balance in mother and newborn

Impact of low-dose aspirin exposure on obstetrical outcomes: a meta-analysis

OBJECTIVE

To assess the impact of low-dose aspirin (LDA) on obstetrical outcomes through a meta-analysis of placebo-controlled randomized controlled trials (RCTs).

METHODS

A systematic search of the PubMed, Cochrane Library, Web of Science and Embase databases from inception to January 2024 was conducted to identify studies exploring the role of aspirin on pregnancy, reporting obstetrical-related outcomes, including preterm birth (PTB, gestational age <37 weeks), small for gestational age (SGA), low birth weight (LBW, birthweight < 2500g), perinatal death (PND), admission to the neonatal intensive care unit (NICU), 5-min Apgar score < 7 and placental abruption. Relative risks (RRs) were estimated for the combined outcomes. Subgroup analyses were performed by risk for preeclampsia (PE), LDA dosage (<100 mg vs. ≥100 mg) and timing of onset (≤20 weeks vs. >20 weeks).

RESULTS

Forty-seven studies involving 59,124 participants were included. Compared with placebo, LDA had a more significant effect on low-risk events such as SGA, PTB and LBW. Specifically, LDA significantly reduced the risk of SGA (RR = 0.91, 95% CI: 0.87-0.95), PTB (RR = 0.93, 95% CI: 0.89-0.97) and LBW (RR = 0.94, 95% CI: 0.89-0.99). For high-risk events, LDA significantly lowered the risk of NICU admission (RR = 0.93, 95% CI: 0.87-0.99). On the other hand, LDA can significantly increase the risk of placental abruption (RR = 1.72, 95% CI: 1.23-2.43). Subgroup analyses showed that LDA significantly reduced the risk of SGA (RR = 0.86, 95% CI: 0.77-0.97), PTB (RR = 0.93, 95% CI: 0.88-0.98) and PND (RR = 0.65, 95% CI: 0.48-0.88) in pregnant women at high risk of PE, whereas in healthy pregnant women LDA did not significantly improve obstetrical outcomes, but instead significantly increased the risk of placental abruption (RR = 5.56, 95% CI: 1.92-16.11). In pregnant women at high risk of PE, LDA administered at doses ≥100 mg significantly reduced the risk of SGA (RR = 0.77, 95% CI: 0.66-0.91) and PTB (RR = 0.56, 95% CI: 0.32-0.97), but did not have a statistically significant effect on reducing the risk of NICU, PND and LBW. LDA started at ≤20 weeks significantly reduced the risk of SGA (RR = 0.76, 95% CI: 0.65-0.89) and PTB (RR = 0.56, 95% CI: 0.32-0.97).

CONCLUSIONS

To sum up, LDA significantly improved neonatal outcomes in pregnant women at high risk of PE without elevating the risk of placental abruption. These findings support LDA's clinical application in pregnant women, although further research is needed to refine dosage and timing recommendations.

Maternal-neonatal events resulting from medications for preventing hypertensive disorders in high-risk pregnant women: A systematic review and network meta-analysis

BACKGROUND

There have been few studies reporting on maternal and neonatal events in high-risk pregnant women receiving medications for preventing hypertensive disorders of pregnancy (HDP).

OBJECTIVE

To identify placental abruption, postpartum hemorrhage, neonatal intraventricular hemorrhage, and neonates with small for gestational age (SGA) or growth restriction resulting from medications for preventing HDP in high-risk pregnant women using a network meta-analysis.

SEARCH STRATEGY

All randomized controlled trials comparing the most commonly used medications (antiplatelet agents, anticoagulants, antioxidants, nitric oxide, and calcium) for preventing HDP in high-risk pregnant women were searched from the Cochrane Pregnancy and Childbirth's Specialized Register of Controlled Trials until July 31, 2020, without language restriction.

SELECTION CRITERIA

Two of the authors independently selected the eligible trials.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data and assessed the methodological quality of the included trials. Pairwise and network meta-analyses were used to determine comparative risk ratios and 95% confidence intervals.

MAIN RESULTS

The 51 included trials involved 69 669 pregnant women. Compared with placebo/no treatment, antioxidants slightly reduced placental abruption with high-certainty evidence. Antiplatelet agents probably reduced SGA with low-certainty evidence and slightly increased neonatal intraventricular hemorrhage with moderate-certainty evidence.

CONCLUSION

Antiplatelet agents probably reduce SGA, but neonatal intraventricular hemorrhage should be monitored.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO, CRD42018096276.

Redefining the Roles of Aspirin across the Spectrum of Cardiovascular Disease Prevention

Even before its role in platelet inhibition was fully characterized in the 1980s, aspirin had been incorporated into the cardiovascular disease care algorithm. Early trials examining its use in unstable angina and acute myocardial infarction revealed evidence of its protective role in the secondary prevention of atherosclerotic cardiovascular disease (ASCVD). Large trials assessing use in the primary prevention setting and optimal dosing regimens were studied in the late 1990s and early 2000s. As a cornerstone of cardiovascular care, aspirin was incorporated into primary and secondary ASCVD prevention guidelines in the United States and mechanical heart valve guidelines. However, in recent years, with significant advances in medical and interventional ASCVD therapies, scrutiny has been placed on the bleeding profile of aspirin, and guidelines have adapted to new evidence. Updates in primary prevention guidelines reserve aspirin only for patients at higher ASCVD risk and low bleeding risk - though questions remain in ASCVD risk assessment as risk-enhancing factors have proven difficult to incorporate on a population level. New thoughts regarding aspirin use in secondary prevention - especially with the concomitant use of anticoagulants - have altered recommendations as additional data accrued. Finally, a recommendation for aspirin and vitamin K antagonists with mechanical heart valves has been modified. Despite aspirin losing a foothold in cardiovascular care, new evidence has strengthened claims for its use in women at high risk for preeclampsia.

Aspirin for the prevention of preeclampsia: A systematic review and meta-analysis of randomized controlled studies

BACKGROUND

The results of randomized controlled studies on aspirin for the prevention of preeclampsia (PE) are conflicting, and some of the related meta-analyses also have limitations or flaws.

DATA SOURCES

A search was conducted on PubMed, Embase, and Cochrane Central Register of Controlled Trials databases, with no time or language restrictions.

STUDY ELIGIBILITY CRITERIA

Randomized controlled studies comparing aspirin for the prevention of PE were conducted.

METHODS

Systematic reviews were performed according to the Cochrane Manual guidelines. A fixed-effects model or a random-effects model was chosen to calculate pooled relative risks with 95% confidence intervals based on the heterogeneity of the included studies. The study aimed to investigate the effect of aspirin on the development of PE in high-risk and general populations of women. Publication bias was assessed by funnel plots. All included studies were assessed for bias by the Cochrane Manual of Bias Assessment. Subgroup analyses were conducted on the aspirin dose, time of initial aspirin intervention, and the region in which the research was conducted, to explore the effective dose of aspirin and time of initial aspirin intervention and to try to find sources of heterogeneity and publication bias.

RESULTS

A total of 39 articles were included, including 29 studies involving pregnant women at high risk for PE (20,133 patients) and 10 studies involving a general population of pregnant women (18,911 patients). Aspirin reduced the incidence of PE by 28% (RR 0.72, 95% CI 0.62-0.83) in women at high risk for PE. Aspirin reduced the incidence of PE by 30% in the general population (RR 0.70, 95% CI 0.52-0.95), but sensitivity analyses found that aspirin in the general population was not robust. A subgroup analysis showed that an aspirin dose of 75 mg/day (RR 0.50, 95% CI 0.32-0.78) had a better protective effect than other doses. Starting aspirin at 12-16 weeks (RR 0.62, 95% CI 0.53-0.74) of gestation or 17-28 weeks (RR 0.62, 95% CI 0.44-0.89) reduced the incidence of PE by 38% in women at high risk for PE, but the results were more reliable for use at 12-16 weeks. Heterogeneity and publication bias of the included studies may be mainly due to the studies completed in Asia.

CONCLUSION

Aspirin is recommended to be started at 12-16 weeks of pregnancy in women at high risk for PE. The optimal dose of aspirin to use is 75 mg/d.

SYSTEMATIC REVIEW REGISTRATION

[www.ClinicalTrials.gov], identifier [CRD42022319984].

Medications for preventing hypertensive disorders in high-risk pregnant women: a systematic review and network meta-analysis

OBJECTIVES

To determine the relative effectiveness of medications for preventing hypertensive disorders in high-risk pregnant women and to provide a ranking of medications using network meta-analysis.

METHODS

All randomized controlled trials comparing the most commonly used medications to prevent hypertensive disorders in high-risk pregnant women that are nulliparity and pregnant women having family history of preeclampsia, history of pregnancy-induced hypertension in previous pregnancy, obstetric risks, or underlying medical diseases. We received the search results from the Cochrane Pregnancy and Childbirth's Specialised Register of Controlled Trials, searched on 31st July 2020. At least two review authors independently selected the included studies and extracted the data and the methodological quality. The comparative risk ratios (RR) and 95% confidence intervals (CI) were analyzed using pairwise and network meta-analyses, and treatment rankings were estimated by the surface under the cumulative ranking curve for preventing preeclampsia (PE), gestational hypertension (GHT), and superimposed preeclampsia (SPE). Safety of the medications is also important for decision-making along with effectiveness which will be reported in a separate review.

RESULTS

This network meta-analysis included 83 randomized studies, involving 93,864 women across global regions. Three medications, either alone or in combination, probably prevented PE in high-risk pregnant women when compared with a placebo or no treatment from network analysis: antiplatelet agents with calcium (RR 0.19, 95% CI 0.04 to 0.86; 1 study; low-quality evidence), calcium (RR 0.61, 95% CI 0.47 to 0.80; 13 studies; moderate-quality evidence), antiplatelet agents (RR 0.69, 95% CI 0.57 to 0.82; 31 studies; moderate-quality evidence), and antioxidants (RR 0.77, 95% CI 0.63 to 0.93; 25 studies; moderate-quality evidence). Calcium probably prevented PE (RR 0.63, 95% CI 0.46 to 0.86; 11 studies; moderate-quality evidence) and GHT (RR 0.89, 95% CI 0.84 to 0.95; 8 studies; high-quality evidence) in nulliparous/primigravida women. Few included studies for the outcome of superimposed preeclampsia were found.

CONCLUSION

Antiplatelet agents, calcium, and their combinations were most effective medications for preventing hypertensive disorders in high-risk pregnant women when compared with a placebo or no treatment. Any high-risk characteristics for women are important in deciding the best medications. The qualities of evidence were mostly rated to be moderate.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018096276.

Toward personalized management of chronic hypertension in pregnancy

Chronic hypertension complicates 1% to 2% of pregnancies, and it is increasingly common. Women with chronic hypertension are an easily recognized group who are in touch with a wide variety of healthcare providers before, during, and after pregnancy, mandating that chronic hypertension in pregnancy be within the scope of many practitioners. We reviewed recent data on management to inform current care and future research. This study is a narrative review of published literature. Compared with normotensive women, women with chronic hypertension are at an increased risk of maternal and perinatal complications. Women with chronic hypertension who wish to be involved in their care can do by measuring blood pressure at home. Accurate devices for home blood pressure monitoring are now readily available. The diagnostic criteria for superimposed preeclampsia remain problematic because most guidelines continue to include deteriorating blood pressure control in the definition. It has not been established how angiogenic markers may aid in confirmation of the diagnosis of superimposed preeclampsia when suspected, over and above information provided by routinely available clinical data and laboratory results. Although chronic hypertension is a strong risk factor for preeclampsia, and aspirin decreases preeclampsia risk, the effectiveness specifically among women with chronic hypertension has been questioned. It is unclear whether calcium has an independent effect in preeclampsia prevention in such women. Treating hypertension with antihypertensive therapy halves the risk of progression to severe hypertension, thrombocytopenia, and elevated liver enzymes, but a reduction in preeclampsia or serious maternal complications has not been observed; however, the lack of evidence for the latter is possibly owing to few events. In addition, treating chronic hypertension neither reduces nor increases fetal or newborn death or morbidity, regardless of the gestational age at which the antihypertensive treatment is started. Antihypertensive agents are not teratogenic, but there may be an increase in malformations associated with chronic hypertension itself. At present, blood pressure treatment targets used in clinics are the same as those used at home, although blood pressure values tend to be inconsistently lower at home among women with hypertension. Although starting all women on the same antihypertensive medication is usually effective in reducing blood pressure, it remains unclear whether there is an optimal agent for such an approach or how best to use combinations of antihypertensive medications. An alternative approach is to individualize care, using maternal characteristics and blood pressure features beyond blood pressure level (eg, variability) that are of prognostic value. Outcomes may be improved by timed birth between 38 0/7 and 39 6/7 weeks' gestation based on observational literature; of note, confirmatory trial evidence is pending. Postnatal care is facilitated by the acceptability of most antihypertensives (including angiotensin-converting enzymes inhibitors) for use in breastfeeding. The evidence base to guide the care of pregnant women with chronic hypertension is growing and aligning with international guidelines. Addressing outstanding research questions would inform personalized care of chronic hypertension in pregnancy.

Dose of aspirin to prevent preterm preeclampsia in women with moderate or high-risk factors: A systematic review and meta-analysis

OBJECTIVE

To evaluate the effect of aspirin dose on the incidence of all gestational age preeclampsia and preterm preeclampsia.

DATA SOURCES

Electronic databases (Cochrane, PubMed, Scopus, ClinicalTrials.gov and the Web of Science) were searched for articles published between January 1985 and March 2019 with no language restrictions.

METHODS

We followed the PRIMSA guidelines and utilized Covidence software. Articles were screened by 2 independent reviewers, with discrepancies settled by an independent 3rd party. Study selection criteria were randomized trials comparing aspirin for prevention of all gestational age and preterm preeclampsia to placebo or no antiplatelet treatment in women aged 15-55 years with moderate or high-risk factors according to the list of risk factors from American College of Obstetricians and Gynecologists and United States Preventive Services Task Force guidelines. The quality of trials was assessed using the Cochrane risk of bias tool. The data were pooled using a random-effects meta-analysis comparing aspirin at doses of <81, 81, 100, and 150 mg. Pre-specified outcomes were all gestational age and preterm preeclampsia.

RESULTS

Of 1,609 articles screened, 23 randomized trials, which included 32,370 women, fulfilled the inclusion criteria. In preterm preeclampsia, women assigned at random to 150 mg experienced a significant 62% reduction in risk of preterm preeclampsia (RR = 0.38; 95% CI: 0.20-0.72; P = 0.011). Aspirin doses <150 mg produced no significant reductions. The number needed to treat with 150 mg of aspirin was 39 (95% CI: 23-100). There was a maximum 30% reduction in risk of all gestational age preeclampsia at all aspirin doses.

CONCLUSIONS

In this meta-analysis, based on indirect comparisons, aspirin at a dose greater than the current, recommended 81 mg was associated with the highest reduction in preterm preeclampsia. Our meta-analysis is limited due to the deficiency of homogeneous high evidence data available in the literature to date; however, it may be prudent for clinicians to consider that the optimal aspirin dose may be higher than the current guidelines advise. Future research to compare the efficacy aspirin doses greater than 81 mg is recommended.

STUDY REGISTRATION

PROSPERO, CRD42019127951 (University of York, UK; http://www.crd.york.ac.uk/PROSPERO/).

The 15-Epilipoxin-A4 Pathway with Prophylactic Aspirin in Preventing Preeclampsia: A Longitudinal Cohort Study

INTRODUCTION

The benefit of aspirin in preventing preeclampsia is increasingly recognized; however, its mechanism of action remains unclear. Nonobstetric studies have described an anti-inflammatory effect of aspirin through the 15-epilipoxin-A4 pathway (aspirin-triggered lipoxin [ATL]). However, the anti-inflammatory mechanism of aspirin in the prevention of preeclampsia remains unknown.

OBJECTIVE/HYPOTHESIS

To examine (1) the difference in longitudinal endogenous lipoxin-A4 (En-Lipoxin-A4) concentration in low-risk (LR) and high-risk (HR) pregnancies, and (2) the effect of aspirin on endogenous ATL concentration and the associated effect on cytokine profile of HR women.

METHODS

Plasma from 220 HR women was collected at 12, 16, 20, 24, 28, 32, and 36 weeks of gestation. Adherence to aspirin was biochemically verified. Plasma En-Lipoxin-A4 and ATL concentrations were analyzed using liquid chromatography mass spectrometry, and cytokines, interleukin (IL)-10, tumor necrosis factor-α, interferon-γ, IL-8, and IL-1β, with the high-sensitivity multibead Luminex® assay.

RESULTS

HR women have up to 70% lower plasma concentration of En-Lipoxin-A4 (P < 0.001) than LR women. HR women with adequate aspirin adherence (HR-AA) (n = 82) had higher plasma concentration of ATL (P < .001), lower concentration of IL-8 from 16 to 36 weeks of gestation (P < .001), and increased IL-10 concentration from 16 to 28 weeks of gestation (P = .03) compared with high-risk women who were not on aspirin (HR-NA). HR-AA who did not develop preeclampsia had higher plasma En-lipoxin-A4 (P < .001), ATL (P = .02), and IL-10 concentrations (P < .001) with lower IL-8 concentration (P = .004) than HR women who developed preeclampsia.

DISCUSSION

Plasma concentration of En-Lipoxin-A4 is lower in HR women than in LR controls. Adequate adherence with aspirin results in an increase in ATL and IL-10 with reduced IL-8 plasma concentration. This study suggests a potential anti-inflammatory role of aspirin through the ATL pathway with prophylactic aspirin in HR pregnant women.

Impact of the ACOG guideline regarding low-dose aspirin for prevention of superimposed preeclampsia in women with chronic hypertension

BACKGROUND

Patients with chronic hypertension are at increased risk for superimposed preeclampsia. The 2016 American College of Obstetricians and Gynecologists guideline recommended initiating 81 mg of daily aspirin for all pregnant women with chronic hypertension to prevent superimposed preeclampsia.

OBJECTIVE

(1) To evaluate the rates of implementation of the 2016 American College of Obstetricians and Gynecologists guideline over time; and (2) to evaluate the effectiveness of aspirin for the prevention of superimposed preeclampsia and other adverse maternal and neonatal outcomes in women with chronic hypertension before and after this guideline.

STUDY DESIGN

This is a retrospective study of women with chronic hypertension who delivered at Thomas Jefferson University Hospital from January 2014 through June 2018. This cohort of women with chronic hypertension was divided into 2 groups, before and after the American College of Obstetricians and Gynecologists recommendation published in September 2016. Daily 81 mg of aspirin was initiated between 12 and 16 weeks. We excluded multiple gestations and incomplete records. The primary outcome was incidence of superimposed preeclampsia, and secondary outcomes were incidence of superimposed preeclampsia with or without severe features, small for gestational age, and preterm birth <37 weeks. Subgroup analysis based on risk stratification was evaluated in women with chronic hypertension requiring antihypertensive medication, history of preeclampsia, and pregestational diabetes.

RESULTS

We identified 457 pregnant women with chronic hypertension, 203 in the post-American College of Obstetricians and Gynecologists group and 254 in the pre-American College of Obstetricians and Gynecologists group. Aspirin 81 mg was offered to 142 (70%) in the post-American College of Obstetricians and Gynecologists group and 18 (7.0%) in the pre-American College of Obstetricians and Gynecologists group. Maternal demographics were not significantly different. The overall incidence of superimposed preeclampsia was not significantly different: 87 (34.3%) vs 72 (35.5%), P=.79, in the pre- and post-American College of Obstetricians and Gynecologists guideline groups, respectively. Superimposed preeclampsia with severe features significantly increased: 32 (12.6%) vs 9 (4.4%), P<.01, whereas superimposed preeclampsia without severe features significantly decreased: 55 (21.7%) vs 63 (31.0%), P=.03. There were no significant differences in small for gestational age neonates or preterm birth <37 weeks incidences between groups. There were no significant differences in the subgroup analysis based on the severity of chronic hypertension requiring antihypertensive medication, history of preeclampsia, or pregestational diabetes.

CONCLUSION

After the adoption of the American College of Obstetricians and Gynecologists guidelines in 70% of the cohort, superimposed preeclampsia, small for gestational age, and preterm birth were not significantly decreased after implementation of aspirin 81 mg initiated between 12 and 16 weeks of gestation.

Aspirin for the prevention of placenta-mediated complications in pregnant women with chronic hypertension

Chronic hypertension affects 1-5% of women of childbearing age. During pregnancy, chronic hypertension is associated with an increased risk of vascular disease such as superimposed preeclampsia (PE), intrauterine growth retardation (IUGR), placental abruption, and preterm delivery. These serious and frequent pathologies, specific to pregnancy, carry a particularly high risk of maternal complications (HELLP syndrome, eclampsia, maternal death) and perinatal complications (perinatal death, neurological disorders). To date, there is no curative treatment of vascular complications of chronic hypertension during pregnancy. The only effective treatment, once the complications are established, is usually stopping the pregnancy and delivering the placenta. Some recommendations suggest the use of low dose aspirin in the prevention of these complications. Although the efficacy of low-dose aspirin is assumed in patients with previous preeclampsia, few studies have evaluated its efficacy in patients with chronic hypertension. Controlled prospective studies using very low doses of aspirin (less than 100 mg) and started after 15 weeks of gestation do not seem conclusive. The objective of this work is first to detail the complications of chronic hypertension during pregnancy, then to analyze the studies which evaluated the interest of low dose aspirin in prevention of the placental vascular complications of the pregnancy in patients with chronic hypertension. We also propose an update on the European and North American national recommendations for the prevention of preeclampsia by low dose aspirin in the high-risk population of patients with chronic hypertension. Finally we present the CHASAP (Chronic Hypertension and Acetyl Salicylic Acid in Pregnancy) trial (NCT04356326), a multicentric prospective randomized double-blind superiority trial, which will compare, in pregnant women with chronic hypertension, the efficacy of low dose aspirin (150 mg/day) with a placebo, in the prevention of maternal-fetal morbidity and mortality (preeclampsia, placental abruption, IUGR, perinatal death, maternal death, and preterm delivery).

Prophylactic aspirin for preventing pre-eclampsia and its complications: An overview of meta-analyses

Benefits of aspirin administration on pre-eclampsia and IUGR depend on the gestational age and dose of aspirin administration. Meta-analyses show that, to prevent preterm labor, aspirin could be administrated even after 16 weeks of gestational age.

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.

Aspirin vs Heparin for the Prevention of Preeclampsia

Preeclampsia is a hypertensive disorder of pregnancy that remains a significant cause of maternal morbidity and mortality worldwide. Preeclampsia can be resolved by delivery, and most of the proposed preventive treatment approaches are based on processes involved in placental development in early pregnancy. Yet, none of these has been established in clinical practice. Low-dose aspirin is the most promising candidate, nevertheless; while some individual randomized controlled trials showed minimal or no statistically significant benefit, recent metanalyses showed that early initiation before 16 weeks of gestation is associated with prevention of early-onset preeclampsia and reduction in prevalence of perinatal death or morbidity of pregnant women. Heparin could be an alternative antithrombotic and anti-inflammatory median to prevent preeclampsia either alone or in combination with aspirin; however, results are conflicting concerning efficacy.

Evaluation of the effectiveness of low-dose aspirin and omega 3 in treatment of asymmetrically intrauterine growth restriction: A randomized clinical trial

OBJECTIVE

To test the effect of aspirin and omega 3 on fetal weight as well as feto-maternal blood flow in asymmetrical intrauterine growth restriction (IUGR).

STUDY DESIGN

This study is a clinically registered (NCT02696577), open, parallel, randomized controlled trial, conducted at Assiut Woman's Health Hospital, Egypt including 80 pregnant women (28-30 weeks) with IUGR. They were randomized either to group I: aspirin or group II: aspirin plus omega 3. The primary outcome was the fetal weight after 6 weeks of treatment. Secondary outcomes included Doppler blood flow changes in both uterine and umbilical arteries, birth weight, time and method of delivery and admission to NICU. The outcome variables were analyzed using paired and unpaired t-test.

RESULTS

The estimated fetal weight increased significant in group II more than group I (p=0.00). The uterine and umbilical arteries blood flow increased significantly in group II (p<0.05). The birth weight in group II was higher than that observed in group I (p<0.05).

CONCLUSION

The using of aspirin with omega 3 is more effective than using aspirin only in increasing fetal weight and improving utero-placental blood flow in IUGR.

Preventing preeclampsia and its fetal complications with low-dose aspirin in East Asians and non-East Asians:A systematic review and meta-analysis

BACKGROUND

Low-dose aspirin can reduce the incidence of preeclampsia and intrauterine growth restriction (IUGR). However, the effects of ethnicity upon low-dose aspirin's efficacy has not been analyzed. Here, we comparatively evaluated the efficacy of low-dose aspirin in preventing preeclampsia and related fetal complications in East Asian and non-East Asian pregnant women at risk for preeclampsia.

METHODS

Several databases were searched for randomized controlled trials (RCTs) comparing low-dose aspirin with either placebo or no treatment in pregnant women at risk for preeclampsia. Odds ratios (ORs) and associated 95% confidence intervals (CIs) for preeclampsia and related fetal outcomes were tabulated.

RESULTS

Low-dose aspirin significantly reduced preeclampsia risk in both East Asians (OR = 0.20, 95% CI: 0.11-0.35) and non-East Asians (OR = 0.84, 95% CI: 0.77-0.92). Low-dose aspirin significantly reduced IUGR risk in East Asians (OR = 0.36, 95% CI: 0.20-0.67) but not in non-East Asians (OR = 0.85, 95% CI: 0.41-1.77). Low-dose aspirin did not significantly reduce the risk of cesarean section in either East Asians (OR = 0.67, 95% CI: 0.14-3.22) or non-East Asians (OR = 1.01, 95% CI: 0.86-1.19).

CONCLUSIONS

Low-dose aspirin is effective in reducing preeclampsia risk in both East Asians and non-East Asians and has differential effects in East Asians and non-East Asians with respect to IUGR.

Infants at risk of cerebral palsy: a systematic review of outcomes used in Cochrane studies of pregnancy, childbirth and neonatology

OBJECTIVE

To systematically review meta-analyses (MAs) and randomised controlled trials (RCTs) of interventions for infants at risk of cerebral palsy (CP), to determine if consensus exists in study end-points.

METHODS

MAs within the "Neonatal" and "Pregnancy and Childbirth" Review Groups in Cochrane Database of Systematic Reviews (to June 2011) were included if they contained risk factors for CP as a study end-point, and were either published in 2010 or 2011 or cited >20 times in Sciverse Scopus. Up to 20 RCTs from each MA were included. Outcome measures, definitions and cut-points for ordinal groupings were extracted from MAs and RCTs and frequencies calculated.

RESULTS

Twenty-two MAs and 165 RCTs were appraised. High consistency existed in types of outcome domains listed as important in MAs. For 10/16 most frequently cited outcome domains, <50% of RCTs contributed data for meta-analyses. Low consistency in outcome definitions, measures, cut-points in RCTs and long-term follow-up prohibited data aggregation.

CONCLUSIONS

Variation in outcome measurement and long-term follow up has hampered the ability of RCTs to contribute data on important outcomes for CP, resulting in lost opportunities to measure the impact of maternal and neonatal interventions. There is an urgent need for and long-term follow up of these interventions and an agreed set of standardised and clinically relevant common data elements for study end-points.

Impact of interventions to prevent and manage preeclampsia and eclampsia on stillbirths

Background

Pre-eclampsia and Eclampsia are relatively common complications of pregnancy, leading to considerable maternal and fetal mortality and morbidity. We sought to review the effect of aspirin, calcium supplementation, antihypertensive agents and magnesium sulphate on risk stillbirths.

Methods

A systematic literature search was conducted to identify studies evaluating the above interventions. We used a standardized abstraction and grading format and performed meta-analyses where data were available from more than one studies. The estimated effect on stillbirths was determined by applying the standard Child Health Epidemiology Reference Group (CHERG) rules for multiple outcomes. For interventions with insufficient evidence for overall effect, a Delphi process was undertaken to estimate effectiveness.

Results

We identified 82 relevant studies. For aspirin, maganesium sulphate and use of antihypertensive we found an insignificant decrease in stillbirth and perinatal mortality. For calcium supplementation, there was a borderline significant reduction in stillbirths (RR 0.81, 95 % CI 0.63-1.03). We undertook a Delphi consultation among experts to assess the potential impact of a package of interventions for the management of pre-eclampsia and eclampsia (antihypertensive, magnesium sulphate and C-section if needed). The Delphi process suggested 20% reduction each in both antepartum and intrapartum stillbirths with the use of this package.

Conclusions

Despite promising benefits of calcium supplementation and aspirin use cases on maternal morbidity and eclampsia in high risk cases, further work is needed to ascertain their benefits in relation to stillbirths. The Delphi process undertaken for assessing potential impact of a package of interventions indicated that this could be associated with 20% reduction in stillbirths, for input into LiST.

Use of acetaminophen during pregnancy and risk of preeclampsia, hypertensive and vascular disorders: a birth cohort study

OBJECTIVE

To examine whether pregnant women who used acetaminophen, a prostaglandinG2 synthase inhibitor, had an increased risk of preeclampsia, gestational hypertension, thromboembolic complications, or abruptio placentae.

METHODS

We selected 63,833 women participating in the Danish National Birth Cohort who gave birth to a live born singleton and had information on acetaminophen use during pregnancy reported by three interviews. Through linkage to the National Hospital Discharge Registry we obtained data from hospital diagnose of the outcomes we study.

RESULTS

Women who used acetaminophen during the third trimester of pregnancy had an increased risk of preeclampsia (adjusted relative risk RR = 1.40, 95% CI: 1.24-1.58). The risk was higher among women who had early preeclampsia (before the 32nd gestational week) (RR = 1.47, 95% CI: 1.12-1.93), severe preeclampsia (RR = 1.51, 95% CI: 1.15-2.00), or chronic hypertension (RR = 1.44, 95% CI: 1.13-1.83). Second and third trimester use was associated with an increased risk of pulmonary embolisms (RR = 3.02, 1.28-7.15) and deep vein thrombosis (RR = 2.15, 1.06-4.37), respectively.

CONCLUSIONS

Acetaminophen use during pregnancy is associated with an increased risk of diseases in which a reduction of prostacyclin during pregnancy has been postulated to play a role, including preeclampsia and thromboembolic diseases.

Low-dose aspirin reduces uteroplacental vascular impedance in early and mid gestation in IVF and ICSI patients: a randomized, placebo-controlled double-blind study

OBJECTIVE

To determine whether low-dose aspirin improves uteroplacental hemodynamics in unselected in-vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) subjects when medication is started concomitantly with controlled ovarian hyperstimulation.

METHODS

Thirty-seven pregnant women who had undergone IVF/ICSI and had been randomized to receive 100 mg aspirin (n = 17) or placebo (n = 20) daily, started concomitantly with controlled ovarian hyperstimulation, were included in this study. Doppler ultrasound examination was performed at 6, 10, 13 and 18 weeks' gestation. Uterine artery (UtA) pulsatility index (PI) was calculated and bilateral UtA notching was noted. Subplacental arcuate artery PI was obtained at 6 and 10 weeks' gestation. Umbilical artery (UA) PI and mean velocity were calculated at 10, 13 and 18 weeks' gestation. In the aspirin group there was one early pregnancy miscarriage, and one patient discontinued the study medication owing to early pregnancy bleeding. A total of 15 women in the aspirin group and 20 women in the placebo group underwent the complete ultrasound protocol.

RESULTS

At 6 weeks' gestation, arcuate artery PI and at 18 weeks' gestation, UtA PI were lower (P < 0.05) in the aspirin group than in the placebo group. At 18 weeks' gestation, bilateral UtA notching tended to be more common in the placebo group (40%) than in the aspirin group (13%) (P = 0.06). UA PI and mean velocity did not differ significantly between the groups.

CONCLUSION

Low-dose aspirin reduces uteroplacental vascular impedance in early and mid pregnancy in unselected IVF/ICSI subjects when medication is started concomitantly with controlled ovarian hyperstimulation.

Pregnancy following eclampsia: a longitudinal study at korle-bu teaching hospital

SUMMARY OBJECTIVE

To find out the reproductive performance of patients in the immediate pregnancy following an eclampsia.

DESIGN

Longitudinal survey.

SETTING

Obstetrics Unit of Department of Obstetrics and Gynaecology in a teaching hospital.

SUBJECTS AND METHODS

Three hundred and ninety seven women whose previous pregnancies were complicated by eclampsia were followed up based on a schedule of antenatal care from 14-16 weeks gestation till delivery. The occurrence of hypertensive complications, timing of delivery, fetal outcome and birth weight were noted.

RESULTS

There were no cases of recurrent eclampsia and no maternal death. Pregnancy-induced hypertension and pre-eclampia recurred in 15.8% of the women. These recurrencies were more significant among those who had changed their male partners (p = 0.0005). The caesarean section rate was 65.9%. The mean ponderal indices in those who developed hypertensive complications were significantly lower than the normotensives (P<0.03 However, the overall perinatal mortality rate of 23.3 per 1000 deliveries was lower than the 62.8 per 1000 in the general obstetric population.

CONCLUSION

Previous episode of eclampsia does not necessarily affect perinatal and maternal outcome adversely in subsequent pregnancy, provided adequate antenatal surveillance and timely delivery are offered to the patients.

WITHDRAWN: Antiplatelet agents for preventing and treating pre-eclampsia

BACKGROUND

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

OBJECTIVES

To assess the effectiveness and safety of antiplatelet agents when given to women at risk of developing pre-eclampsia, and to those with established pre-eclampsia.

SEARCH STRATEGY

This review drew on the search strategy developed for the Pregnancy and Childbirth Group as a whole. The Cochrane Controlled Trials Register was also searched, The Cochrane Library 1999 Issue 1, Embase was searched from 1994-1999 and hand searches were performed of the congress proceedings of the International and European Societies for the Study of Hypertension in Pregnancy.

SELECTION CRITERIA

All randomised trials comparing antiplatelet agents with either placebo or no antiplatelet agent during pregnancy. Quasi random study designs were excluded. Participants were pregnant women considered to be at risk of developing pre-eclampsia, and those with pre-eclampsia before delivery. Women treated postpartum were excluded. Interventions were any comparisons of an antiplatelet agent (such as low dose aspirin or dipyridamole) with either placebo or no antiplatelet agent.

DATA COLLECTION AND ANALYSIS

Assessment of trials for inclusion in the review and extraction of data was performed independently and unblinded by two reviewers. Data were entered into the Review Manager software and double checked.

MAIN RESULTS

Forty two trials involving over 32,000 women were included in this review, with 30,563 women in the prevention trials. There is a 15% reduction in the risk of pre-eclampsia associated with the use of antiplatelet agents [32 trials with 29,331 women; relative risk (RR) 0.85, 95% confidence interval (0.78, 0.92); Number needed to treat (NNT) 89, (59, 167)]. This reduction is regardless of risk status at trial entry or whether a placebo was used, and irrespective of the dose of aspirin or gestation at randomisation.Twenty three trials (28,268 women) reported preterm delivery. There is a small (8%) reduction in the risk of delivery before 37 completed weeks [RR 0.92, (0.88, 0.97); NNT 72 (44, 200)]. Baby deaths were reported in 30 trials (30,093 women). Overall there is a 14% reduction in baby deaths in the antiplatelet group [RR 0.86, (0.75, 0.98); NNT 250 (125, >10000)]. Small for gestational age babies were reported in 25 trials (20,349 women), with no overall difference between the groups, RR 0.92, (0.84, 1.01). There were no significant differences between treatment and control groups in any other measures of outcome. Five trials compared antiplatelet agents with placebo or no antiplatelet agent for the treatment of pre-eclampsia. There are insufficient data for any firm conclusions about the possible effects of these agents when used for treatment of pre-eclampsia.

AUTHORS' CONCLUSIONS

Antiplatelet agents, in this review largely low dose aspirin, have small-moderate benefits when used for prevention of pre-eclampsia. Further information is required to assess which women are most likely to benefit, when treatment should be started, and at what dose.

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 for women at risk of developing pre-eclampsia.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (July 2006), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2005, Issue 1), EMBASE (1994 to November 2005) and handsearched congress proceedings of the International and European Societies for the Study of Hypertension in Pregnancy.

SELECTION CRITERIA

All randomised trials comparing antiplatelet agents with either placebo or no antiplatelet agent were included. Quasi-random studies were excluded. Participants were pregnant women at risk of developing pre-eclampsia. Interventions were any comparisons of an antiplatelet agent (such as low-dose aspirin or dipyridamole) with either placebo or no antiplatelet.

DATA COLLECTION AND ANALYSIS

Two authors assessed trials for inclusion and extracted data independently.

MAIN RESULTS

Fifty-nine trials (37,560 women) are included. There is a 17% reduction in the risk of pre-eclampsia associated with the use of antiplatelet agents ((46 trials, 32,891 women, relative risk (RR) 0.83, 95% confidence interval (CI) 0.77 to 0.89), number needed to treat (NNT) 72 (52, 119)). Although there is no statistical difference in RR based on maternal risk, there is a significant increase in the absolute risk reduction of pre-eclampsia for high risk (risk difference (RD) -5.2% (-7.5, -2.9), NNT 19 (13, 34)) compared with moderate risk women (RD -0.84 (-1.37, -0.3), NNT 119 (73, 333)). Antiplatelets were associated with an 8% reduction in the relative risk of preterm birth (29 trials, 31,151 women, RR 0.92, 95% CI 0.88 to 0.97); NNT 72 (52, 119)), a 14% reduction in fetal or neonatal deaths (40 trials, 33,098 women, RR 0.86, 95% CI 0.76 to 0.98); NNT 243 (131, 1,666) and a 10% reduction in small-for-gestational age babies (36 trials, 23,638 women, RR 0.90, 95% CI0.83 to 0.98). There were no statistically significant differences between treatment and control groups for any other outcomes.

AUTHORS' CONCLUSIONS

Antiplatelet agents, largely low-dose aspirin, have moderate benefits when used for prevention of pre-eclampsia and its consequences. Further information is required to assess which women are most likely to benefit, when treatment is best started, and at what dose.

Síndrome coronario agudo con elevación de ST durante el embarazo: descripción de un caso y revisión de las opciones terapéuticas

ST segment elevation acute coronary syndrome is a clinical condition that is rarely observed in pregnant women. However, its manifestation is a situation of high maternal-fetal risk. Pharmacotherapeutical management of these patients is difficult and requires individualized care by a multidisciplinary team since many of the standard treatments are included within the categories of teratogencity C or D of the Food and Drug Administration and experience with techniques such as coronary angioplasty with stent placement is scarce. The case of a 32-year woman who was 11 weeks pregnant and diagnosed of acute coronary syndrome with ST segment and its therapeutic approach are described. Furthermore, the information available on epidemiology, etiology and pathophysiology of acute coronary syndrome with ST segment during pregnancy and the specific role of the currently available treatment options are reviewed.

Pathophysiology and Medical Management of Systemic Hypertension in Pregnancy

Hypertension in pregnancy includes a group of distinct disorders that require special consideration in both prevention and pharmacologic treatment. In recent years, there have been few advances regarding the pathophysiology and prevention of preeclampsia or in the recommendations for first-line drug therapy for its hypertensive complications. Similarly, the recommendations for pharmacologic treatment of women with chronic hypertension antedating pregnancy have changed little primarily because first-line medications have the advantage of having had more extensive research experience. Recent clinical trials have demonstrated the efficacy and safety of various second-line drugs for the hypertensive disorders of pregnancy; whether these therapies can eventually replace the standard recommended medications will require more extensive long-term investigation.

Prevention of preeclampsia with low-dose aspirin -- a systematic review and meta-analysis of the main randomized controlled trials

The purpose of this paper is to evaluate the effectiveness of low-dose aspirin in the prevention of preeclampsia in low-risk and high-risk women. We identified randomized clinical trials of the use of low-dose aspirin to prevent preeclampsia through the PUBMED search engine, and through the Cochran Library database. Twenty-two studies met our inclusion criteria, and were divided according to the studied population into 2 groups: trials with women at low risk for preeclampsia and trials with women at high risk. Effects were measured through the incidence of preeclampsia in women taking either placebo or aspirin, in studies where the relative risks and the 95% confidence intervals were calculated for both groups. A total of 33,598 women were studied, comprising 5 trials with 16,700 women at low-risk and 17 trials including 16,898 women at high risk. The incidence of preeclampsia was 3.75% (626/17,700), in the low-risk group, 9.01% (1,524/16,898) in the high-risk group, and 6.40% (2,150/33,598) overall. Low-dose aspirin had no statistically significantly effect on the incidence of preeclampsia in the low-risk group (RR = 0.95, 95% CI = 0.81-1.11), but had a small beneficial effect in the high-risk group (RR = 0.87, 95% CI = 0.79-0.96). Therefore, low-dose aspirin is mildly beneficial in terms of reducing the incidence of preeclampsia in women at high risk of developing preeclampsia.

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 platelet-derived vasoconstrictor and stimulant of platelet aggregation. These observations led to the hypotheses that antiplatelet agents, low-dose aspirin in particular, might prevent or delay the development of pre-eclampsia.

OBJECTIVES

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

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register (September 2003), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 2, 2003), EMBASE (1994 to 2003) and we handsearched the congress proceedings of the International and European Societies for the Study of Hypertension in Pregnancy.

SELECTION CRITERIA

All randomised trials comparing antiplatelet agents with either placebo or no antiplatelet agent during pregnancy. Quasi-random study designs were excluded. Participants were pregnant women considered to be at risk of developing pre-eclampsia. Interventions were any comparisons of an antiplatelet agent (such as low-dose aspirin or dipyridamole) with either placebo or no antiplatelet agent.

DATA COLLECTION AND ANALYSIS

Two reviewers assessed trials for inclusion in the review and extracted data. We entered data into the Review Manager software and double checked.

MAIN RESULTS

Fifty-one trials involving 36,500 women are included in this review. There is a 19% reduction in the risk of pre-eclampsia associated with the use of antiplatelet agents ((43 trials, 33,439 women; relative risk (RR) 0.81, 95% confidence interval (CI) 0.75 to 0.88); number needed to treat (NNT) 69 (51, 109)).Twenty-eight trials (31,845 women) reported preterm birth. There is a small (7%) reduction in the risk of delivery before 37 completed weeks ((RR 0.93, 95% CI 0.89 to 0.98); NNT 83 (50, 238)). Fetal or neonatal deaths were reported in 38 trials (34,010 women). Overall there is a 16% reduction in baby deaths in the antiplatelet group (RR 0.84, 95% CI 0.74 to 0.96); NNT 227 (128, 909)). Small-for-gestational age babies were reported in 32 trials (24,310 women), with an 8% reduction in risk (RR 0.92, 95% CI 0.85 to 1.00). There were no significant differences between treatment and control groups in any other measures of outcome.

REVIEWER'S CONCLUSIONS

Antiplatelet agents, in this review largely low-dose aspirin, have small-moderate benefits when used for prevention of pre-eclampsia. Further information is required to assess which women are most likely to benefit, when treatment is best started, and at what dose.

Low-dose aspirin in pregnancy: maternal and neonatal aspirin concentrations and neonatal prostanoid formation

OBJECTIVE

To evaluate maternal and neonatal plasma concentrations of acetylsalicylic acid and salicylic acid and the neonatal endogenous prostanoid formation during low-dose aspirin prophylaxis (LDA; 100 mg daily) in pregnant women.

METHODS

Concentrations of acetylsalicylic acid and salicylic acid in maternal plasma after at least 4 weeks of LDA (n = 14) and in umbilical cord plasma of newborns after maternal LDA (n = 7) were determined by gas chromatography-mass spectrometry. Platelet and renal formation of thromboxane A2 and the formation of prostaglandin E2 and prostacyclin were evaluated in vivo by quantification of index metabolites in plasma and urine by gas chromatography-mass spectrometry in neonates after maternal LDA (n = 14) and in a control group.

RESULTS

In the pregnant women, acetylsalicylic acid and salicylic acid concentrations rapidly increased after ingestion of LDA. Acetylsalicylic acid was completely eliminated within 4 hours, whereas salicylic acid was detected with low concentrations at 18 and 21 hours after dosing. In the neonates, acetylsalicylic acid was not detected. Salicylic acid was detected in 1 infant only. Platelet thromboxane A2 formation in the newborn infants was significantly suppressed but recovered within 2 to 3 days after discontinuation of LDA. Renal thromboxane A2 formation and the formation of prostaglandin E2 and prostacyclin were not affected by LDA.

CONCLUSION

In pregnant women who are treated with LDA, acetylsalicylic acid is not completely inactivated in the portal circulation but reaches the uteroplacental circulation and exerts antiplatelet effects in the fetus and newborn.

Chronic hypertension in pregnancy

Pregnant women with chronic hypertension are at risk for maternal and perinatal morbidity. Careful assessment and management of these patients during pregnancy are the keys to reducing maternal and fetal complications. Antihypertensive treatment should be used in women with high-risk chronic hypertension, whereas drug therapy does not improve pregnancy outcome in women at low risk. Prophylactic low-dose aspirin started early in pregnancy in women with chronic hypertension is not effective in reducing the frequency of superimposed preeclampsia and should be avoided.

Prevention of pre-eclampsia: status and perspectives 2000

Because pre-eclampsia is a relatively common complication of pregnancy and forms a major cause of maternal, fetal, and neonatal morbidity and mortality, attempts at prevention are justified, but hampered by the fact that as yet no reliable and acceptable screening tests for women at risk are available. Analysis of the many interventions advocated to prevent or delay the onset of pre-eclampsia reveals that dietary calcium supplementation and prophylactic low-dose aspirin treatment have shown promise of efficacy in small randomized, placebo-controlled trials, but the results of large, multicenter trials are generally disappointing. The disappointing results obtained in large, multicenter trials may in part be explained by the lack of strict criteria for inclusion, late initiation of treatment, use of ill-defined end points, different timing of aspirin ingestion, and low patient compliance. Recent evidence that supplementation with vitamins C and E could prevent pre-eclampsia awaits confirmation. Future clinical trials on prevention of pre-eclampsia should be based on results of basic research.

Umbilical cord serum levels of thromboxane B2 in term infants of women who participated in a placebo-controlled trial of low-dose aspirin

OBJECTIVE

Our aim was to quantify thromboxane B2 (TXB2) in umbilical cord serum of term infants of nulliparous, low-risk women who were randomly assigned to either placebo or low-dose (60 mg) aspirin (ASA) on a daily basis from 24 weeks' gestation through delivery as part of a randomized clinical trial for prevention of preeclampsia.

METHODS

Umbilical cord sera from 230 singleton, term infants whose mothers were involved in our low-dose ASA trial were assayed for TXB2, the stable metabolite of thromboxane A2, without knowledge of treatment or outcome data. The data were related to assigned treatment group, longitudinal pattern of maternal serum TXB2 levels, and other maternal and newborn characteristics. The data also were analyzed according to whether or not maternal serum levels of TXB2 at 29-31, 34-36, and delivery were reduced > or =50% compared to values prior to initiation of the trial.

RESULTS

Umbilical cord TXB2 levels (ng/ml, mean +/- SE) were significantly lower at term in the ASA group (36.1 +/- 3.3, n = 111) than in the placebo group (56.6 +/- 5.7, n = 119; P = 0.002). Umbilical cord TXB2 levels were correlated to those in maternal serum at delivery in the ASA group (r = 0.3441; P = 0.0005) but not in the placebo group (r = 0.0626; P = 0.53). Regardless of assigned treatment group, infants whose mothers had a > or =50% longitudinal reduction in serum TXB2 had lower umbilical cord TXB2 levels (39.2 +/- 3.6, n = 114) than infants whose mothers had <50% reductions in TXB2 (54.6 +/- 5.9, n = 116; P = 0.027). Birthweights of these infants correlated inversely (r = 0.1678, P = 0.017) with maternal serum TXB2 at delivery but not to umbilical cord TXB2 levels; the best correlation between birthweight and maternal serum TXB2 was noted in pregnancies assigned to receive placebo (r = -0.2558, P = 0.009).

CONCLUSIONS

Umbilical cord serum levels of TXB2 1) are reduced in instances of long-term maternal ingestion of ASA, 2) correlate well with maternal serum levels of TXB2 at delivery when there is evidence for consistent maternal use of ASA, but 3) do not correlate with maternal serum TXB2 levels when there is no evidence for frequent maternal ingestion of cyclooxygenase inhibitors. These data suggest that the capacity for platelet production of TXA2 in fetal and maternal compartments are regulated independently. Finally, there is an inverse relationship between maternal serum TXB2 levels at delivery and birthweight of newborn infants that is most evident among the pregnancies assigned to placebo and also among pregnancies in which there was little evidence to suggest a pattern of cyclooxygenase inhibitor use during pregnancy.

Antiplatelet agents for preventing and treating pre-eclampsia

BACKGROUND

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

OBJECTIVES

To assess the effectiveness and safety of antiplatelet agents when given to women at risk of developing pre-eclampsia, and to those with established pre-eclampsia.

SEARCH STRATEGY

This review drew on the search strategy developed for the Pregnancy and Childbirth Group as a whole. The Cochrane Controlled Trials Register was also searched, The Cochrane Library 1999 Issue 1, Embase was searched from 1994-1999 and hand searches were performed of the congress proceedings of the International and European Societies for the Study of Hypertension in Pregnancy.

SELECTION CRITERIA

All randomised trials comparing antiplatelet agents with either placebo or no antiplatelet agent during pregnancy. Quasi random study designs were excluded. Participants were pregnant women considered to be at risk of developing pre-eclampsia, and those with pre-eclampsia before delivery. Women treated postpartum were excluded. Interventions were any comparisons of an antiplatelet agent (such as low dose aspirin or dipyridamole) with either placebo or no antiplatelet agent.

DATA COLLECTION AND ANALYSIS

Assessment of trials for inclusion in the review and extraction of data was performed independently and unblinded by two reviewers. Data were entered into the Review Manager software and double checked.

MAIN RESULTS

Forty two trials involving over 32,000 women were included in this review, with 30,563 women in the prevention trials. There is a 15% reduction in the risk of pre-eclampsia associated with the use of antiplatelet agents [32 trials with 29,331 women; relative risk (RR) 0.85, 95% confidence interval (0.78, 0.92); Number needed to treat (NNT) 89, (59, 167)]. This reduction is regardless of risk status at trial entry or whether a placebo was used, and irrespective of the dose of asprin or gestation at randomisation. Twenty three trials (28,268 women) reported preterm delivery. There is a small (8%) reduction in the risk of delivery before 37 completed weeks [RR 0.92, (0.88, 0.97); NNT 72 (44, 200)]. Baby deaths were reported in 30 trials (30,093 women). Overall there is a 14% reduction in baby deaths in the antiplatelet group [RR 0.86, (0. 75, 0.98); NNT 250 (125, >10000)]. Small for gestational age babies were reported in 25 trials (20,349 women), with no overall difference between the groups, RR 0.92, (0.84, 1.01). There were no significant differences between treatment and control groups in any other measures of outcome. Five trials compared antiplatelet agents with placebo or no antiplatelet agent for the treatment of pre-eclampsia. There are insufficient data for any firm conclusions about the possible effects of these agents when used for treatment of pre-eclampsia.

REVIEWER'S CONCLUSIONS

Antiplatelet agents, in this review largely low dose aspirin, have small-moderate benefits when used for prevention of pre-eclampsia. Further information is required to assess which women are most likely to benefit, when treatment should be started, and at what dose.

Predictive markers of pre-eclampsia in hypertensive disorders of pregnancy

OBJECTIVE

The aim of this work is to assess the most widespread methods currently proposed and two new markers for predicting the development of pre-eclampsia in pregnant women with hypertension.

METHODS

The study involved 212 pregnant Caucasian women: 104 normotensive, 68 pregnancy-induced hypertensive and 40 chronic hypertensive. Blood and urine were sampled between 28 and 30 weeks gestation. All 108 hypertensive pregnant women, at the time of sampling, demonstrated proteinuria below 0.3 g/24 h. The following laboratory tests were performed: fibronectin, antithrombin-III, alpha-1-microglobulin, U-N-acetyl-beta-glucosaminidase, uric acid and albumin excretion rate. Student's t-test, discriminant analysis and chi2 (chi-square) test were used as statistical methods. A P value less than 0.05 was considered significant.

RESULTS

After discriminating analysis, only three of the six variables analyzed were able to discriminate patients who would develop pre-eclampsia from the remaining hypertensive pregnant women: microalbuminuria, uric acid and fibronectin (chi2 = 29.122, P < 0.01).

CONCLUSIONS

In agreement with previous studies, albumin excretion rate appeared to be the best predictive test for pre-eclampsia in hypertensive pregnant women, giving a higher positive predictive value and specificity (87.5 and 98.9%, respectively).

Chronic hypertension in pregnancy

Pregnancies in women with chronic hypertension are at increased risk of superimposed pre-eclampsia, abruptio placentae, fetal growth retardation and prematurity. The frequencies of these complications are increased in those women who have high-risk chronic hypertension, ie severe hypertension or pre-existing cardiovascular or renal diseases, as well as in those with target organ damage. Such women should receive antihypertensive therapy and close management to improve maternal and fetal outcome. In women with low-risk chronic hypertension, antihypertensive treatments do not improve pregnancy outcome. Prophylactic low-dose acetylsalicylic acid treatment does not reduce the frequency of superimposed pre-eclampsia nor does it improve perinatal outcome in these pregnancies.

Low-dose aspirin to prevent preeclampsia in women at high risk. National Institute of Child Health and Human Development Network of Maternal-Fetal Medicine Units

BACKGROUND

Whether low-dose aspirin prevents preeclampsia is unclear. It is not recommended as prophylaxis in women at low risk for preeclampsia but may reduce the incidence of the disease in women at high risk.

METHODS

We conducted a double-blind, randomized, placebo-controlled trial in four groups of pregnant women at high risk for preeclampsia, including 471 women with pregestational insulin-treated diabetes mellitus, 774 women with chronic hypertension, 688 women with multifetal gestations, and 606 women who had had preeclampsia during a previous pregnancy. The women were enrolled between gestational weeks 13 and 26 and received either 60 mg of aspirin or placebo daily.

RESULTS

Outcome data were obtained on all but 36 of the 2539 women who entered the study. The incidence of preeclampsia was similar in the 1254 women in the aspirin group and the 1249 women in the placebo group (aspirin, 18 percent; placebo, 20 percent; P=0.23). The incidences in the aspirin and placebo groups for each of the four high-risk categories were also similar: for women with pregestational diabetes mellitus, the incidence was 18 percent in the aspirin group and 22 percent in the placebo group (P=0.38); for women with chronic hypertension, 26 percent and 25 percent (P= 0.66); for those with multifetal gestations, 12 percent and 16 percent (P=0.10); and for those with preeclampsia during a previous pregnancy, 17 percent and 19 percent (P=0.47). In addition, the incidences of perinatal death, preterm birth, and infants small for gestational age were similar in the aspirin and placebo groups.

CONCLUSIONS

In our study, low-dose aspirin did not reduce the incidence of preeclampsia significantly or improve perinatal outcomes in pregnant women at high risk for preeclampsia.

A randomized controlled trial of low-dose aspirin in women at risk from pre-eclampsia

OBJECTIVES

To determine whether low-dose aspirin reduces the incidence of pre-eclampsia, reduces perinatal mortality and improves birth weights in pregnant women considered at high risk of developing pre-eclampsia.

METHOD

Two-hundred fifty subjects were recruited from the antenatal clinics at Harare Central Hospital with either a previous history of pregnancy-induced hypertension or pre-existing chronic hypertension and were randomized to receive either 75 mg of aspirin (ASA) or placebo (PLA).

RESULTS

Two-hundred thirty subjects (ASA, n = 113; PLA, n = 117) completed the trial. The odds of developing pre-eclampsia for those on aspirin was 0.72 times those on placebo (95% CI, 0.34-1.52). The mean birth weight was 2774 g for those on aspirin and 2694 g for those on placebo (P = 0.80). No difference was noted in the perinatal deaths (OR = 0.38; 95% CI, 0.10-1.20).

CONCLUSION

Prophylactic use of aspirin was not associated with a significant effect on the major pregnancy outcomes assessed in this study.

Randomised controlled trial of ketanserin and aspirin in prevention of pre-eclampsia

BACKGROUND

Pre-eclampsia is associated with extensive endothelial-cell damage and platelet activation, resulting in lower production of vasodilator prostaglandins and increased release of the vasoconstrictors thromboxane A2 and serotonin. Damage to endothelial-cell serotonin-1 receptors leaves vasoconstriction and platelet aggregation mediated by serotonin-2 receptors unopposed. We investigated the role of ketanserin, a selective serotonin-2-receptor antagonist, in lowering the rate of pre-eclampsia among pregnant women with mild to moderate hypertension.

METHODS

We recruited 138 pregnant women into a double-blind, randomised, placebo-controlled trial. They had diastolic blood pressure persistently more than 80 mm Hg before 20 weeks' gestation. 69 women received ketanserin and 69 received placebo. Both groups also received aspirin. Patients were initially given two tablets daily, increased to four tablets daily in diastolic blood pressure was more than 90 mm Hg. Primary outcomes were the development of pre-eclampsia and severe hypertension, and perinatal mortality.

FINDINGS

There were significantly fewer cases of pre-eclampsia (two vs 13; relative risk 0.15 [95% CI 0.04-0.66], p = 0.006) and severe hypertension (six vs 17; p = 0.02) in the ketanserin than in the placebo group. There was also a trend towards less perinatal mortality (one vs six deaths) but this was not significant (p = 0.28). Rates of abruptio placentae and pre-eclampsia before 34 weeks' gestation were lower in the ketanserin group, and mean birthweight was significantly higher.

INTERPRETATION

We found an association between the addition of ketanserin to aspirin and a decrease in the number of cases of pre-eclampsia and severe hypertension, as well as improved pregnancy outcome among patients with mild to moderate midtrimester hypertension.

A meta-analysis of low dose aspirin for the prevention of intrauterine growth retardation

OBJECTIVE

To determine more precisely the effect of prophylactic low dose aspirin on intrauterine growth retardation and perinatal mortality.

DESIGN

Meta-analysis of 13 published randomised clinical trials.

METHODS

We searched 18 medical databases, including MEDLINE since 1964 and EMBASE since 1974, review articles and the references from each retrieved report to identify all studies evaluating the effect of aspirin in pregnancy and including both intrauterine growth retardation and perinatal mortality as outcome measures.

RESULTS

Among 13,234 women from 13 studies between 1985 and 1994, aspirin showed a significant reduction in intrauterine growth retardation (IUGR) (OR 0.82; 95% CI 0.72-0.93; P = 0.003) and a nonsignificant reduction in perinatal mortality (OR 0.84; 95% CI 0.66-1.08; P = 0.18). Subgroup analyses revealed that aspirin was effective at lower doses between 50 and 80 mg/day (IUGR: OR 0.87; 95% CI 0.76-0.99; mortality: OR 0.90, 95% CI 0.70-1.16), but that the preventive effect was greater at higher doses between 100 and 150 mg/day (IUGR: OR 0.36, 95% CI 0.22-0.59; mortality: OR 0.40, 95% CI 0.16-0.97) and among women entered before the 17th week of gestation (IUGR: OR 0.35, 95% CI 0.21-0.58; mortality: OR 0.43, 95% CI 0.17-1.06). We did not identify any specific subgroup of women most likely to benefit from aspirin treatment.

CONCLUSION

The results of this meta-analysis showed that early aspirin treatment reduced the risk of intrauterine growth retardation. Low dose aspirin should not be used routinely in pregnant women until those most likely to benefit from aspirin treatment have been clearly identified.