Heparin for pregnant women with acquired or inherited thrombophilias

Venous thromboembolism prophylaxis for women at risk during pregnancy and the early postnatal period

BACKGROUND

Venous thromboembolism (VTE), although rare, is a major cause of maternal mortality and morbidity. Some women are at increased risk of VTE during pregnancy and the early postnatal period (e.g. caesarean section, family history of VTE, or thrombophilia), and so prophylaxis may be considered. As some methods of prophylaxis carry risks of adverse effects, and risk of VTE is often low, benefits of thromboprophylaxis may be outweighed by harms.

OBJECTIVES

To assess the effects of thromboprophylaxis during pregnancy and the early postnatal period on the risk of venous thromboembolic disease and adverse effects in women at increased risk of VTE.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (18 October 2019). In addition, we searched ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) for unpublished, planned and ongoing trial reports (18 October 2019).

SELECTION CRITERIA

Randomised trials comparing one method of thromboprophylaxis with placebo or no treatment, or two (or more) methods of thromboprophylaxis.

DATA COLLECTION AND ANALYSIS

At least two review authors assessed trial eligibility, extracted data, assessed risk of bias, and judged certainty of evidence for selected critical outcomes (using GRADE). We conducted fixed-effect meta-analysis and reported data (all dichotomous) as summary risk ratios (RRs) with 95% confidence intervals (CIs).

MAIN RESULTS

Twenty-nine trials (involving 3839 women), overall at moderate to high risk of bias were included. Trials were conducted across the antenatal, peripartum and postnatal periods, with most in high-income countries. Interventions included types and regimens of heparin (low molecular weight heparin (LMWH) and unfractionated heparin (UFH)), hydroxyethyl starch (HES), and compression stockings or devices. Data were limited due to a small number of trials in comparisons and/or few or no events reported. All critical outcomes (assessed for comparisons of heparin versus no treatment/placebo, and LMWH versus UFH) were considered to have very low-certainty evidence, downgraded mainly for study limitations and imprecise effect estimates.  Maternal death was not reported in most studies. Antenatal (± postnatal) prophylaxis For the primary outcomes symptomatic thromboembolic events pulmonary embolism (PE) and/or deep vein thrombosis (DVT), and the critical outcome of adverse effects sufficient to stop treatment, the evidence was very uncertain.  Symptomatic thromboembolic events: - heparin versus no treatment/placebo (RR 0.39; 95% CI 0.08 to 1.98; 4 trials, 476 women; very low-certainty evidence); - LMWH versus UFH (RR 0.47; 95% CI 0.09 to 2.49; 4 trials, 404 women; very low-certainty evidence); Symptomatic PE: - heparin versus no treatment/placebo (RR 0.33; 95% CI 0.02 to 7.14; 3 trials, 187 women; very low-certainty evidence); - LMWH versus UFH (no events; 3 trials, 287 women); Symptomatic DVT: - heparin versus no treatment/placebo (RR 0.33; 95% CI 0.04 to 3.10; 4 trials, 227 women; very low-certainty evidence); - LMWH versus UFH (no events; 3 trials, 287 women); Adverse effects sufficient to stop treatment: - heparin versus no treatment/placebo (RR 0.49; 95% CI 0.05 to 5.31; 1 trial, 139 women; very low-certainty evidence); - LMWH versus UFH (RR 0.07; 95% CI 0.01 to 0.54; 2 trials, 226 women; very low-certainty evidence). Peripartum/postnatal prophylaxis Vaginal or caesarean birth When UFH and no treatment were compared, the effects on symptomatic thromboembolic events (RR 0.16; 95% CI 0.02 to 1.36; 1 trial, 210 women; very low-certainty evidence), symptomatic PE (RR 0.16; 95% CI 0.01 to 3.34; 1 trial, 210 women; very low-certainty evidence), and symptomatic DVT  (RR 0.27; 95% CI 0.03 to 2.55; 1 trial, 210 women; very low-certainty evidence) were very uncertain.  Maternal death and adverse effects sufficient to stop treatment were not reported. Caesarean birth Symptomatic thromboembolic events: - heparin versus no treatment/placebo (RR 1.30; 95% CI 0.39 to 4.27; 4 trials, 840 women; very low-certainty evidence); - LMWH versus UFH (RR 0.33; 95% CI 0.01 to 7.99; 3 trials, 217 women; very low-certainty evidence); Symptomatic PE: - heparin versus no treatment/placebo (RR 1.10; 95% CI 0.25 to 4.87; 4 trials, 840 women; very low-certainty evidence); - LMWH versus UFH (no events; 3 trials, 217 women);  Symptomatic DVT: - heparin versus no treatment/placebo (RR 1.30; 95% CI 0.24 to 6.94; 5 trials, 1140 women; very low-certainty evidence); LMWH versus UFH (RR 0.33; 95% CI 0.01 to 7.99; 3 trials, 217 women; very low-certainty evidence); Maternal death: - heparin versus placebo (no events, 1 trial, 300 women); Adverse effects sufficient to stop treatment: - heparin versus placebo (no events;  1 trial, 140 women). Postnatal prophylaxis No events were reported for LMWH versus no treatment/placebo for: symptomatic thromboembolic events, symptomatic PE and symptomatic DVT (all 2 trials, 58 women), or maternal death (1 trial, 24 women). Adverse effects sufficient to stop treatment were not reported. We were unable to conduct subgroup analyses due to lack of data. Sensitivity analysis including the nine studies at low risk of bias did not impact overall findings.

AUTHORS' CONCLUSIONS

The evidence is very uncertain about benefits and harms of VTE thromboprophylaxis in women during pregnancy and the early postnatal period at increased risk of VTE. Further high-quality very large-scale randomised trials are needed to determine effects of currently used treatments in women with different VTE risk factors. As sufficiently large definitive trials are unlikely to be funded, secondary data analyses based on high-quality registry data are important.

Epidural therapy for the treatment of severe pre-eclampsia in non labouring women

BACKGROUND

Pre-eclampsia is a pregnancy-specific multi-organ disorder, which is characterised by hypertension and multisystem organ involvement and which has significant maternal and fetal morbidity and mortality. Failure of the placental vascular remodelling and reduced uteroplacental flow form the etiopathological basis of pre-eclampsia. There are several established therapies for pre-eclampsia including antihypertensives and anticonvulsants. Most of these therapies aim at controlling the blood pressure or preventing complications of elevated blood pressure, or both. Epidural therapy aims at blocking the vasomotor tone of the arteries, thereby increasing uteroplacental blood flow. This review was aimed at evaluating the available evidence about the possible benefits and risks of epidural therapy in the management of severe pre-eclampsia, to define the current evidence level of this therapy, and to determine what (if any) further evidence is required.

OBJECTIVES

To assess the effectiveness, safety and cost of the extended use of epidural therapy for treating severe pre-eclampsia in non-labouring women. This review aims to compare the use of extended epidural therapy with other methods, which include intravenous magnesium sulphate, anticonvulsants other than magnesium sulphate, with or without use of the antihypertensive drugs and adjuncts in the treatment of severe pre-eclampsia.This review only considered the use of epidural anaesthesia in the management of severe pre-eclampsia in the antepartum period and not as pain relief in labour.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) (13 July 2017) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) or quasi-RCTs comparing epidural therapy versus traditional therapy for pre-eclampsia in the form of antihypertensives, anticonvulsants, magnesium sulphate, low-dose dopamine, corticosteroids or a combination of these, were eligible for inclusion. Trials using a cluster design, and studies published in abstract form only are also eligible for inclusion in this review. Cross-over trials were not eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

The two review authors independently assessed trials for inclusion and trial quality. There were no relevant data available for extraction.

MAIN RESULTS

We included one small study (involving 24 women). The study was a single-centre randomised trial conducted in Mexico. This study compared a control group who received antihypertensive therapy, anticonvulsant therapy, plasma expanders, corticosteroids and dypyridamole with an intervention group that received epidural block instead of the antihypertensives, as well as all the other four drugs. Lumbar epidural block was given using 0.25% bupivacaine, 10 mg bolus and 5 mg each hour on continuous epidural infusion for six hours. This study was at low risk of bias in three domains but was assessed to be high risk of bias in two domains due to lack of allocation concealment and blinding of women and staff, and unclear for random sequence generation and outcome assessor blinding.The included study did not report on any of this review's important outcomes. Meta-analysis was not possible.For the mother, these were: maternal death (death during pregnancy or up to 42 days after the end of the pregnancy, or death more than 42 days after the end of the pregnancy); development of eclampsia or recurrence of seizures; stroke; any serious morbidity: defined as at least one of stroke, kidney failure, liver failure, HELLP syndrome (haemolysis, elevated liver enzymes and low platelets), disseminated intravascular coagulation, pulmonary oedema.For the baby, these were: death: stillbirths (death in utero at or after 20 weeks' gestation), perinatal deaths (stillbirths plus deaths in the first week of life), death before discharge from the hospital, neonatal deaths (death within the first 28 days after birth), deaths after the first 28 days; preterm birth (defined as the birth before 37 completed weeks' gestation); and side effects of the intervention. Reported outcomesThe included study only reported on a single secondary outcome of interest to this review: the Apgar score of the baby at birth and after five minutes and there was no clear difference between the intervention and control groups.The included study also reported a reduction in maternal diastolic arterial pressure. However, the change in maternal mean arterial pressure and systolic arterial pressure, which were the other reported outcomes of this trial, were not significantly different between the two groups.

AUTHORS' CONCLUSIONS

Currently, there is insufficient evidence from randomised controlled trials to evaluate the effectiveness, safety or cost of using epidural therapy for treating severe pre-eclampsia in non-labouring women.High-quality randomised controlled trials are needed to evaluate the use of epidural agents as therapy for treatment of severe pre-eclampsia. The rationale for the use of epidural is well-founded. However there is insufficient evidence from randomised controlled trials to show that the effect of epidural translates into improved maternal and fetal outcomes. Thus, there is a need for larger, well-designed studies to come to an evidence-based conclusion as to whether the lowering of vasomotor tone by epidural therapy results in better maternal and fetal outcomes and for how long that could be maintained. Another important question that needs to be answered is how long should extended epidural be used to ensure any potential clinical benefits and what could be the associated side effects and costs. Interactions with other modalities of treatment and women's satisfaction could represent other avenues of research.

Aspirin and/or heparin for women with unexplained recurrent miscarriage with or without inherited thrombophilia

BACKGROUND

Since hypercoagulability might result in recurrent miscarriage, anticoagulant agents could potentially increase the chance of live birth in subsequent pregnancies in women with unexplained recurrent miscarriage, with or without inherited thrombophilia.

OBJECTIVES

To evaluate the efficacy and safety of anticoagulant agents, such as aspirin and heparin, in women with a history of at least two unexplained miscarriages with or without inherited thrombophilia.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (1 October 2013) and scanned bibliographies of all located articles for any unidentified articles.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials that assessed the effect of anticoagulant treatment on live birth in women with a history of at least two unexplained miscarriages with or without inherited thrombophilia were eligible. Interventions included aspirin, unfractionated heparin (UFH), and low molecular weight heparin (LMWH) for the prevention of miscarriage. One treatment could be compared with another or with no-treatment (or placebo).

DATA COLLECTION AND ANALYSIS

Two review authors (PJ and SK) assessed the studies for inclusion in the review and extracted the data. If necessary they contacted study authors for more information. We double checked the data.

MAIN RESULTS

Nine studies, including data of 1228 women, were included in the review evaluating the effect of either LMWH (enoxaparin or nadroparin in varying doses) or aspirin or a combination of both, on the chance of live birth in women with recurrent miscarriage, with or without inherited thrombophilia. Studies were heterogeneous with regard to study design and treatment regimen and three studies were considered to be at high risk of bias. Two of these three studies at high risk of bias showed a benefit of one treatment over the other, but in sensitivity analyses (in which studies at high risk of bias were excluded) anticoagulants did not have a beneficial effect on live birth, regardless of which anticoagulant was evaluated (risk ratio (RR) for live birth in women who received aspirin compared to placebo 0.94, (95% confidence interval (CI) 0.80 to 1.11, n = 256), in women who received LMWH compared to aspirin RR 1.08 (95% CI 0.93 to 1.26, n = 239), and in women who received LMWH and aspirin compared to no-treatment RR 1.01 (95% CI 0.87 to 1.16) n = 322).Obstetric complications such as preterm delivery, pre-eclampsia, intrauterine growth restriction and congenital malformations were not significantly affected by any treatment regimen. In included studies, aspirin did not increase the risk of bleeding, but treatment with LWMH and aspirin increased the risk of bleeding significantly in one study. Local skin reactions (pain, itching, swelling) to injection of LMWH were reported in almost 40% of patients in the same study.

AUTHORS' CONCLUSIONS

There is a limited number of studies on the efficacy and safety of aspirin and heparin in women with a history of at least two unexplained miscarriages with or without inherited thrombophilia. Of the nine reviewed studies quality varied, different treatments were studied and of the studies at low risk of bias only one was placebo-controlled. No beneficial effect of anticoagulants in studies at low risk of bias was found. Therefore, this review does not support the use of anticoagulants in women with unexplained recurrent miscarriage. The effect of anticoagulants in women with unexplained recurrent miscarriage and inherited thrombophilia needs to be assessed in further randomised controlled trials; at present there is no evidence of a beneficial effect.

Aspirin and/or heparin for women with unexplained recurrent miscarriage with or without inherited thrombophilia

BACKGROUND

Since hypercoagulability might result in recurrent miscarriage, anticoagulant agents could potentially increase the chance of live birth in subsequent pregnancies in women with unexplained recurrent miscarriage, with or without inherited thrombophilia.

OBJECTIVES

To evaluate the efficacy and safety of anticoagulant agents, such as aspirin and heparin, in women with a history of at least two unexplained miscarriages with or without inherited thrombophilia.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (1 October 2013) and scanned bibliographies of all located articles for any unidentified articles.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials that assessed the effect of anticoagulant treatment on live birth in women with a history of at least two unexplained miscarriages with or without inherited thrombophilia were eligible. Interventions included aspirin, unfractionated heparin (UFH), and low molecular weight heparin (LMWH) for the prevention of miscarriage. One treatment could be compared with another or with no-treatment (or placebo).

DATA COLLECTION AND ANALYSIS

Two review authors (PJ and SK) assessed the studies for inclusion in the review and extracted the data. If necessary they contacted study authors for more information. We double checked the data.

MAIN RESULTS

Nine studies, including data of 1228 women, were included in the review evaluating the effect of either LMWH (enoxaparin or nadroparin in varying doses) or aspirin or a combination of both, on the chance of live birth in women with recurrent miscarriage, with or without inherited thrombophilia. Studies were heterogeneous with regard to study design and treatment regimen and three studies were considered to be at high risk of bias. Two of these three studies at high risk of bias showed a benefit of one treatment over the other, but in sensitivity analyses (in which studies at high risk of bias were excluded) anticoagulants did not have a beneficial effect on live birth, regardless of which anticoagulant was evaluated (risk ratio (RR) for live birth in women who received aspirin compared to placebo 0.94, (95% confidence interval (CI) 0.80 to 1.11, n = 256), in women who received LMWH compared to aspirin RR 1.08 (95% CI 0.93 to 1.26, n = 239), and in women who received LMWH and aspirin compared to no-treatment RR 1.01 (95% CI 0.87 to 1.16) n = 322).Obstetric complications such as preterm delivery, pre-eclampsia, intrauterine growth restriction and congenital malformations were not significantly affected by any treatment regimen. In included studies, aspirin did not increase the risk of bleeding, but treatment with LWMH and aspirin increased the risk of bleeding significantly in one study. Local skin reactions (pain, itching, swelling) to injection of LMWH were reported in almost 40% of patients in the same study.

AUTHORS' CONCLUSIONS

There is a limited number of studies on the efficacy and safety of aspirin and heparin in women with a history of at least two unexplained miscarriages with or without inherited thrombophilia. Of the nine reviewed studies quality varied, different treatments were studied and of the studies at low risk of bias only one was placebo-controlled. No beneficial effect of anticoagulants in studies at low risk of bias was found. Therefore, this review does not support the use of anticoagulants in women with unexplained recurrent miscarriage. The effect of anticoagulants in women with unexplained recurrent miscarriage and inherited thrombophilia needs to be assessed in further randomised controlled trials; at present there is no evidence of a beneficial effect.

Prophylaxis for venous thromboembolic disease in pregnancy and the early postnatal period

BACKGROUND

Venous thromboembolism (VTE), although rare, is a major cause of maternal mortality and morbidity, and methods of prophylaxis are therefore often used for women considered to be at risk. This may include women who have given birth by caesarean section, those with a personal or family history of VTE and women with inherited or acquired thrombophilias (conditions that predispose people to thrombosis). Many methods of prophylaxis carry risks of adverse effects, and as the risk of VTE is often low, it is possible that the benefits of thromboprophylaxis may be outweighed by harms. Guidelines for clinical practice have been based on expert opinion rather than high-quality evidence from randomised trials.

OBJECTIVES

To assess the effects of thromboprophylaxis in women who are pregnant or have recently given birth and are at increased risk of VTE on the incidence of VTE and adverse effects of treatment.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (27 November 2013). 

SELECTION CRITERIA

Randomised trials comparing one method of thromboprophylaxis with placebo or no treatment, and randomised trials comparing two (or more) methods of thromboprophylaxis.

DATA COLLECTION AND ANALYSIS

At least two review authors assessed trial eligibility and quality and extracted the data.

MAIN RESULTS

Nineteen trials, at an overall moderate risk of bias, met the inclusion criteria for the review. Only 16 trials, involving 2592 women, assessing a range of methods of thromboprophylaxis, contributed data to the review. Six trials compared methods of antenatal prophylaxis: heparin versus no treatment/placebo (two trials), and low molecular weight heparin (LMWH) versus unfractionated heparin (UFH) (four trials). Nine trials assessed prophylaxis after caesarean section: four compared heparin with placebo; three compared LMWH with UFH; one compared hydroxyethyl starch (HES) with UFH; and one compared five-day versus 10-day LMWH. One study examined prophylaxis with UFH in the postnatal period (including following vaginal births).For antenatal prophylaxis, none of the included trials reported on maternal mortality, and no differences were detected for the other primary outcomes of symptomatic thromboembolic events, symptomatic pulmonary embolism (PE) and symptomatic deep venous thrombosis (DVT) when LMWH or UFH was compared with no treatment/placebo or when LMWH was compared with UFH. The risk ratios (RR) for symptomatic thromboembolic events were: antenatal LMWH/UFH versus no heparin, RR 0.33; 95% confidence interval (CI) 0.04 to 2.99 (two trials, 56 women); and antenatal LMWH versus UFH, RR 0.47; 95% CI 0.09 to 2.49 (four trials, 404 women). No differences were shown when antenatal LMWH or UFH was compared with no treatment/placebo for any secondary outcomes. Antenatal LMWH was associated with fewer adverse effects sufficient to stop treatment (RR 0.07; 95% CI 0.01 to 0.54; two trials, 226 women), and fewer fetal losses (RR 0.47; 95% CI 0.23 to 0.95; three trials, 343 women) when compared with UFH. In two trials, antenatal LMWH compared with UFH was associated with fewer bleeding episodes (defined in one trial of 121 women as bruises > 1 inch (RR 0.18, 95% CI 0.09 to 0.36); and in one trial of 105 women as injection site haematomas of ≥ 2 cm, bleeding during delivery or other bleeding (RR 0.28; 95% CI 0.15 to 0.53)), however in a further trial of 117 women no difference between groups was shown for bleeding at delivery. The results for these secondary outcomes should be interpreted with caution, being derived from small trials that were not of high methodological quality.For post-caesarean/postnatal prophylaxis, only one trial comparing five-day versus 10-day LMWH after caesarean section reported on maternal mortality, observing no deaths. No differences were seen across any of the comparisons for the other primary outcomes (symptomatic thromboembolic events, symptomatic PE and symptomatic DVT). The RRs for symptomatic thromboembolic events were: post-caesarean LMWH/UFH versus no heparin, RR 1.30; 95% CI 0.39 to 4.27 (four trials, 840 women); post-caesarean LMWH versus UFH, RR 0.33; 95% CI 0.01 to 7.99 (three trials, 217 women); post-caesarean five-day versus 10-day LMWH, RR 0.36; 95% CI 0.01 to 8.78 (one trial, 646 women); postnatal UFH versus no heparin, RR 0.16; 95% CI 0.02 to 1.36 (one trial, 210 women). For prophylaxis after caesarean section, in one trial (of 580 women), women receiving UFH and physiotherapy were more likely to have bleeding complications ('complications hémorragiques') than women receiving physiotherapy alone (RR 5.03; 95% CI 2.49 to 10.18). In two additional trials, that compared LMWH with placebo, no difference between groups in bleeding episodes (major bleeding; major bruising; bleeding/bruising reported at discharge) were detected. No other differences in secondary outcomes were shown when LMWH was compared with UFH post-caesarean, nor when post-caesarean HES was compared with UFH, post-caesarean five-day LMWH was compared with 10-day LMWH, or when UFH was compared to no heparin postnatally.

AUTHORS' CONCLUSIONS

There is insufficient evidence on which to base recommendations for thromboprophylaxis during pregnancy and the early postnatal period, with the small number of differences detected in this review being largely derived from trials that were not of high methodological quality. Large scale, high-quality randomised trials of currently used interventions are warranted.

Antithrombotic therapy for improving maternal or infant health outcomes in women considered at risk of placental dysfunction

BACKGROUND

Pregnancy complications such as pre-eclampsia and eclampsia, intrauterine growth restriction and placental abruption are thought to have a common origin related to abnormalities in the development and function of the placenta.

OBJECTIVES

To compare, using the best available evidence, the benefits and harms of antenatal antithrombotic therapy to improve maternal or infant health outcomes in women considered at risk of placental dysfunction, when compared with other treatments, placebo or no treatment.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (17 July 2012).

SELECTION CRITERIA

Randomised controlled trials comparing antenatal antithrombotic therapy (either alone or in combination with other agents) with placebo or no treatment, or any other treatment in the antenatal period to improve maternal or infant health outcomes in women considered at risk of placental dysfunction.

DATA COLLECTION AND ANALYSIS

Two review authors evaluated trials under consideration for appropriateness for inclusion and methodological quality without consideration of their results according to the prestated eligibility criteria. We used a fixed-effect meta-analysis for combining study data if the trials were judged to be sufficiently similar. We investigated heterogeneity by calculating I² statistic, and if this indicated a high level of heterogeneity among the trials included, we used a random-effects model.

MAIN RESULTS

Our search strategy identified 18 reports of 14 studies for consideration. The original review included five studies (484 women) which met the inclusion criteria, with a further five studies included in the updated review, involving an additional 655 women. The overall quality of the included trials was considered fair to good.Nine studies compared heparin (alone or in combination with dipyridamole or low-dose aspirin) with no treatment; and one compared trapidil (triazolopyrimidine).While this review identified the use of heparin to be associated with a statistically significant reduction in risk of perinatal mortality (six studies; 653 women; risk ratio (RR) 0.40; 95% confidence intervals (CI) 0.20 to 0.78), preterm birth before 34 (three studies; 494 women; RR 0.46; 95% CI 0.29 to 0.73) and 37 (five studies; 621 women; RR 0.72; 95% CI 0.58 to 0.90) weeks' gestation, and infant birthweight below the 10th centile for gestational age (seven studies; 710 infants; RR 0.41; 95% CI 0.27 to 0.61), there is a lack of reliable information available related to clinically relevant, serious adverse infant health outcomes, which have not been reported to date.

AUTHORS' CONCLUSIONS

While treatment with heparin for women considered to be at particularly high risk of adverse pregnancy complications secondary to placental insufficiency was associated with a statistically significant reduction in risk of perinatal mortality, preterm birth before 34 and 37 weeks' gestation, and infant birthweight below the 10th centile for gestational age when compared with no treatment for women considered at increased risk of placental dysfunction, to date, important information about serious adverse infant and long-term childhood outcomes is unavailable.

Pre-eclampsia

Pre-eclampsia remains a leading cause of maternal and perinatal mortality and morbidity. It is a pregnancy-specific disease characterised by de-novo development of concurrent hypertension and proteinuria, sometimes progressing into a multiorgan cluster of varying clinical features. Poor early placentation is especially associated with early onset disease. Predisposing cardiovascular or metabolic risks for endothelial dysfunction, as part of an exaggerated systemic inflammatory response, might dominate in the origins of late onset pre-eclampsia. Because the multifactorial pathogenesis of different pre-eclampsia phenotypes has not been fully elucidated, prevention and prediction are still not possible, and symptomatic clinical management should be mainly directed to prevent maternal morbidity (eg, eclampsia) and mortality. Expectant management of women with early onset disease to improve perinatal outcome should not preclude timely delivery-the only definitive cure. Pre-eclampsia foretells raised rates of cardiovascular and metabolic disease in later life, which could be reason for subsequent lifestyle education and intervention.

Antithrombotic therapy for improving maternal or infant health outcomes in women considered at risk of placental dysfunction

BACKGROUND

Pregnancy complications such as pre-eclampsia and eclampsia, intrauterine growth restriction and placental abruption are thought to have a common origin related to abnormalities in the development and function of the placenta.

OBJECTIVES

To compare, using the best available evidence, the benefits and harms of antenatal antithrombotic therapy to improve maternal or infant health outcomes in women considered at risk of placental dysfunction, when compared with other treatments, placebo or no treatment.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (March 2010).

SELECTION CRITERIA

Randomised controlled trials comparing antenatal antithrombotic therapy (either alone or in combination with other agents) with placebo or no treatment, or any other treatment in the antenatal period to improve maternal or infant health outcomes in women considered at risk of placental dysfunction.

DATA COLLECTION AND ANALYSIS

Two review authors evaluated trials under consideration for appropriateness for inclusion and methodological quality without consideration of their results according to the prestated eligibility criteria. We used a fixed-effect meta-analysis for combining study data if the trials were judged to be sufficiently similar. We investigated heterogeneity by calculating I(2) statistic, and if this indicated a high level of heterogeneity among the trials included we used a random-effects model.

MAIN RESULTS

Our search strategy identified 14 reports of 10 studies for consideration, of which five met the inclusion criteria, involving 484 women. Four studies compared heparin (alone or in combination with dipyridamole) with no treatment; and one compared trapidil (triazolopyrimidine). While there were no statistically significant differences identified for the primary outcomes following heparin treatment, it was associated with a reduction in the risk of pre-eclampsia, eclampsia, and infant birthweight less than the 10th centile for gestational age.

AUTHORS' CONCLUSIONS

The review identified no significant differences for the primary outcomes perinatal mortality, preterm birth less than 34 weeks' gestation, and childhood neurodevelopmental handicap, although the number of studies and participants was small. While treatment with heparin appears promising with a reduction in pre-eclampsia, eclampsia, and infant birthweight less than the 10th centile for gestational age, the number of studies and participants included was small, and to date important information about serious adverse infant and long-term childhood outcomes is unavailable. Further research is required.

Prophylaxis for venous thromboembolic disease in pregnancy and the early postnatal period

BACKGROUND

Venous thromboembolic disease (TED), although rare, is a major cause of maternal mortality and morbidity, hence methods of prophylaxis are often used for women at risk. This may include women delivered by caesarean section, those with a personal or family history of TED and women with inherited or acquired thrombophilias (conditions that predispose people to thrombosis). Many methods of prophylaxis carry a risk of side effects, and as the risk of TED is low, it is possible that the benefits of thromboprophylaxis may be outweighed by harm. Current guidelines for clinical practice are based on expert opinion only, rather than high quality evidence from randomised trials.

OBJECTIVES

To determine the effects of thromboprophylaxis in women who are pregnant or have recently delivered and are at increased risk of TED on the incidence of venous TED and side effects of treatment.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (May 2009).

SELECTION CRITERIA

Randomised trials comparing one method of thromboprophylaxis with placebo or no treatment, and randomised trials comparing two (or more) methods of thromboprophylaxis.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data independently and resolved any discrepancies by discussion.

MAIN RESULTS

Sixteen trials met the inclusion criteria but only 13 trials, involving 1774 women, examining a range of methods of thromboprophylaxis, contributed data for the outcomes of interest. Four of them compared methods of antenatal prophylaxis: low molecular weight heparin (LMWH) versus unfractionated heparin (UFH) (two studies), and heparin versus no treatment (two studies). Eight studies assessed postnatal prophylaxis after caesarean section; one compared hydroxyethyl starch with unfractionated heparin; four compared heparin with placebo; and the other three compared UFH with LMWH. One study examined prophylaxis in the postnatal period.The small number of statistically significant findings in this review are largely derived from trials which are not of high methodological quality. It was not possible to assess the effects of any of these interventions on most outcomes, and especially on rare outcomes such as death, TED and osteoporosis, because of small sample sizes and the small number of trials making the same comparisons.There was some evidence of side effects associated with thromboprophylaxis.

AUTHORS' CONCLUSIONS

There is insufficient evidence on which to base recommendations for thromboprophylaxis during pregnancy and the early postnatal period. Large scale randomised trials of currently-used interventions should be conducted.

Aspirin or anticoagulants for treating recurrent miscarriage in women without antiphospholipid syndrome

BACKGROUND

Since hypercoagulability might result in recurrent miscarriage, anticoagulant agents could potentially increase the live-birth rate in subsequent pregnancies in women with either inherited thrombophilia or unexplained recurrent miscarriage.

OBJECTIVES

To evaluate the efficacy and safety of anticoagulant agents, such as aspirin and heparin, in women with a history of at least two miscarriages without apparent causes other than inherited thrombophilia.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (April 2008), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2007, Issue 1), MEDLINE (January 1966 to March 2007), and EMBASE (1980 to March 2007). We scanned bibliographies of all located articles for any unidentified articles.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials that assessed the effect of anticoagulant treatment on the live-birth rate in women with a history of at least two miscarriages (up to 20 weeks of amenorrhoea) without apparent causes other than inherited thrombophilia were eligible. Interventions included aspirin, unfractionated heparin, and low molecular weight heparin for the prevention of miscarriage. One treatment could be compared with another or with placebo.

DATA COLLECTION AND ANALYSIS

Two authors assessed the trials for inclusion in the review and extracted the data. We double checked the data.

MAIN RESULTS

Two studies (189 participants) were included in the review. In one study, 54 pregnant women with recurrent miscarriage (RM) but no detectable anticardiolipin antibodies were randomised to low-dose aspirin or placebo. RM was defined as three or more consecutive miscarriages (occurring before 22 weeks' gestational age (based on last menstrual period)). Similar live-birth rates were observed with aspirin and placebo, both 81% (risk ratio (RR) 1.00, 95% confidence interval (CI) 0.78 to 1.29). In the other study, 107 women with consecutive recurrent miscarriage without any apparent cause and no hereditary thrombophilia were randomised between enoxaparin and aspirin. Here RM was stated as three or more consecutive first trimester miscarriages or at least two consecutive second trimester miscarriages. Similar live birth rates were observed with enoxaparin and aspirin, respectively 82% and 84% (RR 0.97, 95% CI 0.81 to 1.16).

AUTHORS' CONCLUSIONS

There is a paucity in studies on the efficacy and safety of aspirin and heparin in women with a history of at least two miscarriages without apparent causes other than inherited thrombophilia. The two reviewed trials studied different treatments and only one study was placebo-controlled. Neither of the studies showed a benefit of one treatment over the other. Therefore, the use of anticoagulants in this setting is not recommended. However, large randomised placebo-controlled trials are still urgently needed.

A systematic review of Cochrane anticoagulation reviews

CONTEXT

I coauthored a published review of anticoagulation for venous thromboembolism in the Cochrane Database of Systematic Reviews and published a review on the same topic in MedGenMed (now the Medscape Journal of Medicine). In contrast to the article in Medscape, the discussion and conclusions in the Cochrane review were altered appreciably during the review process. Consequently, I decided to critique all anticoagulation drug-related reviews and protocols in the Cochrane database with feedback letters concerning any issues of potential controversy.

EVIDENCE ACQUISITION

Using key words in the search engine of the Cochrane Reviews, I located reviews and protocols involving anticoagulant drugs. I critiqued each anticoagulation review and protocol and sent a total of 57 feedback letters to Cochrane concerning each publication to elicit a response/rebuttal from the authors.

EVIDENCE SYNTHESIS

Cochrane anticoagulation review editors acknowledged receipt of all letters. As of 12 months after receipt of my last letter, the Cochrane authors have replied to 13 of the 57 and agreed with many of my points. Two protocols were withdrawn after my feedback letters were acknowledged. The 58 Cochrane anticoagulation drug reviews, including mine, contained 9 categories of methodological errors (207 total instances) and 4 types of biases (18 total instances). This review of those Cochrane reviews suggests that the effectiveness of anticoagulants for 30 medical indications is questionable.

CONCLUSIONS

The efficacy of anticoagulants for treatment and prophylaxis for 30 current medical indications should be reconsidered by the scientific community and medical regulatory agencies. At least 50,000 people per year worldwide have fatal bleeding due to anticoagulant treatment or prophylaxis for these indications.

Internal jugular venous thrombosis after in vitro fertilization

Internal jugular vein thrombosis is an uncommon entity with high morbidity and an increased risk of mortality. Spontaneous clotting of the internal jugular vein without any known risk factors is virtually unheard of, and intravenous drug use is the most common cause for thrombosis. Assisted reproductive techniques alone or in conjunction with ovarian hyperstimulation syndrome seem to predispose patients for thrombosis of the internal jugular vein. We present the case of a patient who, after in vitro fertilization, developed ovarian hyperstimulation syndrome and clotted the internal jugular vein. In the setting of the Emergency Department, the norm should be to "rule out internal jugular venous thrombosis" in pregnant patients who have undergone in vitro fertilization and present with neck pain, with or without swelling or distended collaterals.

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.