Scolaris Content Display Scolaris Content Display

胎児の神経保護を目的とした妊婦に対するクレアチン

Contraer todo Desplegar todo

アブストラクト

背景

クレアチンはアミノ酸誘導体で、リン酸化された場合(クレアチンリン酸)、クレアチンキナーゼ反応を介してアデノシン三リン酸(ATP)補充に関与する。細胞が獲得するクレアチンの割合は、魚類、肉類、乳製品が豊富な食品由来のクレアチンと、アルギニン、グリシンおよびメチオニンから生合成したクレアチンが約50:50である。動物実験では、妊娠中の母親に食餌を介してクレアチンを摂取させた場合、胎児の神経保護作用が認められる可能性が示された。妊娠中(胎児の障害が明らかな時点、疑われる時点または可能性がある時点で)の女性にクレアチンを投与した場合、胎児の神経保護作用が認められる可能性があり、その結果、胎児の脳損傷に起因する脳性麻痺やこれに関連する機能障害および身体障害などの有害な神経発達アウトカムのリスクが軽減されるかどうかを評価することは重要である。

目的

胎児の神経保護にクレアチンを使用した場合の効果を評価すること。

検索戦略

Cochrane Pregnancy and Childbirth Group's Trials Registerを検索した(2014年11月30日)。

選択基準

既報、未発表、継続中のすべてのランダム化試験および準ランダム化試験を組み入れる予定であった。全文掲載の論文だけでなく、アブストラクトのみ報告された試験も組み入れる予定であった。クロスオーバーデザインおよびクラスターランダム化デザインの試験は除外した。

胎児の神経保護を目的に妊婦にクレアチンを投与した場合(投与経路、投与時期、用量、期間は問わず)と、プラセボ、無治療または胎児の神経保護作用を目的とした他の薬剤を比較した試験を組み入れる予定であった。異なるクレアチン投与法の比較も組み入れる予定であった。

データ収集と分析

既に終了した、または現在継続中のランダム化比較試験は同定されなかった。

主な結果

本レビューの対象となるランダム化比較試験はなかった。

著者の結論

本レビューの対象となるランダム化比較試験が同定されなかったため、クレアチン投与の影響について言及することができない。動物実験で得られたエビデンスは、妊娠中の母親にクレアチンを投与した場合、胎児の神経保護作用が認められることを支持しているが、胎児の神経保護を目的とした妊婦へのクレアチン投与を評価した試験は、これまで発表されていない。クレアチンが母胎および胎児に安全であることが確立されたら、まず、クレアチンと無介入(プラセボの使用が望ましい)または胎児の神経保護を目的とした他の薬剤(超早産児に対する硫酸マグネシウムなど)を比較したランダム化試験を実施すべきである。適切であれば、これらの試験の後にさまざまなクレアチン投与法(用量および曝露期間)を比較した試験を実施すべきである。これらの試験は質が高く、母親および胎児の短期および長期アウトカム(脳性麻痺などの神経発達障害を含む)を評価するのに十分な検出力を有していなければならない。また、医療の利用および費用についても考慮すべきである。

PICO

Population
Intervention
Comparison
Outcome

El uso y la enseñanza del modelo PICO están muy extendidos en el ámbito de la atención sanitaria basada en la evidencia para formular preguntas y estrategias de búsqueda y para caracterizar estudios o metanálisis clínicos. PICO son las siglas en inglés de cuatro posibles componentes de una pregunta de investigación: paciente, población o problema; intervención; comparación; desenlace (outcome).

Para saber más sobre el uso del modelo PICO, puede consultar el Manual Cochrane.

一般語訳

胎児の神経保護を目的とした妊婦に対するクレアチン

本レビューでは、妊婦にクレアチンを投与して胎児の脳の保護に役立つかどうかを調べたランダム化比較試験を見出すことができなかった。

発達中の胎児の脳は、子宮感染、胎盤の血行不良、長時間にわたる胎児血液の低酸素状態などが原因で損傷を受けやすい。妊娠中に発達中の脳が損傷を受けると胎児が死亡する場合があり、生存した場合は、聴覚障害、視覚障害、言語障害、知的障害、脳性麻痺など生涯にわたる問題が発生する。

クレアチンは細胞のエネルギー産生および体内組織が消費するエネルギーの貯蔵に関与している。クレアチンの主な働きは、エネルギー需要が高くかつ変動しやすい体内組織でアデノシン二リン酸(ADP)をアデノシン三リン酸(ATP)に再生させることである。成人はクレアチン1日要求量の約半分を新鮮な魚、肉および乳製品を含む食事から摂取する。残りのクレアチンは体内でアミノ酸から合成する(蛋白の塊を作る)。動物実験から、クレアチンを妊娠中の母親に投与した場合、発達中の胎児の脳を損傷から保護できる可能性が示唆された。妊婦以外(脳に外傷を負った小児、神経変性疾患の成人など)を対象としたヒト試験では、有望な結果が得られており、クレアチンが脳を保護できることが示唆される。また、これらの試験ではいかなる危険性も認められなかったことからも、クレアチンの有望性が確認できる。

妊娠中に胎児の障害が明らかな時点、疑われる時点または可能性がある時点で妊婦にクレアチンを投与し、胎児の脳の保護に役立つかどうかを評価した、既に終了した(または現在継続中の)ランダム化比較試験は同定されなかった。クレアチンが子宮内における胎児の脳損傷に対する保護作用を有するかどうかを確認するためには、ランダム化比較試験が必要である。これらの試験では、小児期および成人期への発達に対するクレアチンの効果をモニターするため、産児を長期間追跡する必要がある。

Authors' conclusions

Implications for practice

As we did not identify any eligible trials for inclusion in this review, we are unable to comment on implications for practice regarding the use of creatine for women in pregnancy for neuroprotection of the fetus.

Implications for research

The available animal studies of creatine in pregnancy for fetal neuroprotection provide some insight into the potential benefits of this intervention.

Research efforts are currently being directed towards understanding creatine biology in human pregnancy, including identifying whether pregnancies in which creatine concentrations are low are associated with poorer pregnancy outcomes or vice versa. While these studies will be informative for understanding creatine biology in human pregnancy, the absence of such associations will not preclude the possibility that creatine supplementation, above concentrations normally observed toward the end of pregnancy, could provide fetal neuroprotection. Before human trials are conducted, it will be important to determine whether taking creatine during pregnancy is safe for the mother and fetus; studies in larger animals, more comparable to the human, such as primates, will be helpful in establishing this.

If the safety and efficacy of creatine treatment are established, randomised controlled trials in humans are required to provide reliable evidence about the benefits and harms of creatine for this indication. Such randomised controlled trials in human pregnancy should first compare creatine supplementation with either no intervention (ideally a placebo), or with an alternative agent aimed at fetal neuroprotection. If appropriate, these trials should then be followed by studies comparing different creatine regimens (dosage and duration of exposure). Trials must be of a high quality and adequately powered to assess the comparative effects on fetal, infant and child mortality, child morbidity including cerebral palsy and other neurosensory disabilities, maternal outcomes including adverse effects, and the use of health services.

Background

Description of the condition

Fetal brain injury: causes and consequences

The developing fetal brain is vulnerable to damage arising from hypoxia, infection/inflammation, and release of excitatory amino acids, and thus compromise of placental perfusion (via uterine or umbilical blood flow), trans‐placental oxygen delivery, or increased pro‐inflammatory cytokines in the intrauterine environment, increases the risk of brain injury (and/or abnormal brain development) for both the preterm (before 37 weeks' gestation) and term fetus (Rees 2011). Fetal brain injury is a major contributor to perinatal mortality and morbidity worldwide (Jensen 2003), with such injury being associated with a spectrum of life‐long functional and behavioural disorders.

Injury to both the preterm and term developing brain is known to be associated with life‐long and devastating sequelae, such as hearing, sight and speech disorders, seizures, intellectual disability, and motor impairments that may manifest as cerebral palsy (Vexler 2001). Cerebral palsy is an umbrella term, describing "a group of disorders of the development of movement and posture, causing activity limitations, which are attributed to non progressive disturbances that occurred in the developing fetal or infant brain" (Bax 2005). Cerebral palsy is a complex neurological condition, and is often found alongside cognitive, communication, sight and hearing impairments, or epilepsy, pain, behaviour, and sleep disorders (Novak 2012). It is the most common physical disability in childhood, and the most severe physical disability within the spectrum of developmental delay. While for a small number of individuals brain injury acquired after birth may lead to the development of cerebral palsy, for the vast majority (94%) with cerebral palsy, the injury leading to this condition occurs to the fetal brain in utero or to the infant brain before one month of age (ACPR Group 2009).

While a number of causes of fetal brain injury have been recognised (such as intrauterine infection, placental insufficiency, and chronic fetal hypoxia leading to metabolic derangement), episodes of cerebral hypoxia‐ischaemia (reduced oxygen in the blood combined with reduced blood flow to the brain) appear to be important in a great number of cases (whether being acute, chronic, associated with inflammation, or as an antecedent of preterm birth) (du Plessis 2002; Rees 2011; Volpe 2001). Similarly, a great number of potential predisposing factors and causal pathways for cerebral palsy and associated impairments and disabilities have been identified. While it has been shown that neuronal cell injury predominates in term infants, and cerebral white matter injury predominates in premature infants (Volpe 2001), recent evidence suggests that white matter injury is also present in term infants, and grey matter injury in preterm infants (Rees 2011).

Though preterm birth has been recognised as one of the most important risk factors for cerebral palsy (Blair 2006; Jacobsson 2002; McIntyre 2013) (with preterm infants being at an increased risk of white matter injury such as periventricular leukomalacia, and of intraventricular haemorrhage (Larroque 2003)), approximately 60% of all children with cerebral palsy are born at term (ACPR Group 2009; McIntyre 2013; Wu 2003). For infants born at term, antenatal or intrapartum risk factors for cerebral palsy consistently identified in the literature have included small‐for‐gestational age, low birthweight, and placental abnormalities (Blair 2006; McIntyre 2013). Maternal bleeding in the second and third trimesters (McIntyre 2013), hypertension in pregnancy (McIntyre 2013), pre‐eclampsia (Blair 2006; McIntyre 2013), perinatal infection (such as chorioamnionitis) (Blair 2006; McIntyre 2013; Wu 2003), and increasing fetal plurality (Blair 2006) have each been shown to increase the risk of cerebral palsy and associated neurosensory disorders across all gestational ages. For term infants, intrapartum birth asphyxia (a condition resulting from deprivation of oxygen to a newborn, lasting long enough to cause physical harm) has also been shown to be an important predictor of brain injury and later disability (Dilenge 2001; McIntyre 2013).

Following cerebral hypoxia and ischaemia, it is believed that a sequence of pathophysiological events ultimately leading to cell death (via necrosis or apoptosis) are triggered, involving for example, the overstimulation of N‐methyl‐D‐aspartate (NMDA) type glutamate receptors, the accumulation of calcium in cells, and the activation of deleterious events mediated by calcium (including the stimulation of enzymes such as nitric oxide synthase, and the production of oxygen free radicals) (Jensen 2003; Johnston 2000; Rees 2011). Studies of the developing fetal brain have shown that the nature and severity of insult, and gestational age at the time of injury, can greatly influence the subsequent neuropathology. An important common feature of the fetal brain in all such situations, however, is the depletion of cellular energy.

To date, there is minimal knowledge regarding effective strategies to prevent, reduce, or remove the risk of antenatally acquired fetal brain injury and, accordingly, prevent the potentially devastating life‐long consequences for the infant, child, and adult. Magnesium sulphate, when given to the mother prior to very preterm birth, is one of the first antenatal interventions shown to be effective in reducing the risk of death and cerebral palsy for the infant (Doyle 2009). While the precise mechanism of action of magnesium sulphate for neuroprotection of the fetus is not known, experimental evidence and animal studies support several possible neuroprotective effects, for example, magnesium has been shown to prevent excitotoxic calcium‐induced cell injury, through non‐competitive voltage‐dependent inhibition of the NMDA receptor to glutamate (thereby reducing calcium influx) (Marret 2007). In the Doyle 2009 Cochrane review, magnesium sulphate, when administered for the mother prior to preterm birth, was associated with a 32% relative reduction in the risk of cerebral palsy (risk ratio (RR) 0.68, 95% confidence interval (CI) 0.54 to 0.87; five trials; 6145 infants), with 63 babies needing to be treated to benefit one baby by avoiding cerebral palsy, and 42 babies treated to benefit one baby by avoiding death or cerebral palsy (Doyle 2009). While the benefits of this therapy for preterm infants were established in this Cochrane review, not all infants exposed to therapy showed improved outcomes (the absolute risk of cerebral palsy for infants exposed to antenatal magnesium sulphate was 3.4% and 5.0% for infants unexposed) (Doyle 2009). Currently, there is insufficient evidence to assess the efficacy and safety of magnesium sulphate when administered to women for neuroprotection of the term fetus (Nguyen 2013), and there are potential (though commonly minor) adverse effects for the mother associated with this treatment (Bain 2013). At present, other agents being investigated for providing antenatal fetal neuroprotection include maternally administered melatonin (Wilkinson 2013) and allopurinol (Kaandorp 2010; Kaandorp 2012); and while it has previously been shown that antenatal corticosteroids, when given prior to preterm birth, can reduce the risk of cerebroventricular haemorrhage, respiratory distress, necrotising enterocolitis, and death for the neonate, the evidence for benefits into childhood, including reductions in neurodevelopmental delay and cerebral palsy, are less clear (Roberts 2006).

Following recent advances in understanding the mechanisms of fetal brain injury and in identifying predisposing factors, further promise has been raised for the development of primary preventative strategies, based on preventing the complex sequence of pathophysiological and biochemical events that induce irreversible injury. Ideally, a primary preventative agent would be cost‐effective (and/or inexpensive), have a low potential for toxicity, be easily administered to women either in the inpatient or outpatient setting (i.e. available to those with low obstetric monitoring), and be broadly applicable, such that it may offer protection to both the preterm and near‐term fetal brain in a range of obstetric situations, including known or suspected maternal/fetal compromise.

Description of the intervention

Creatine

Creatine is a simple guanidine compound, which may be synthesised endogenously from the amino acids arginine, glycine, and methionine, in the liver, kidney, and pancreas (Adcock 2002). It may also be ingested, through the consumption of dairy, fish, and meat, and is found throughout the human body, including in the brain (Rees 2011). Creatine is taken up into tissues via the creatine transporter and stored as creatine or phosphocreatine. Phosphocreatine is readily converted to creatine via creatine kinase, in a reversible reaction that yields a high energy phosphate allowing the conversion of adenosine diphosphate (ADP) to adenosine triphosphate (ATP) (Wallimann 1992).

A number of studies have demonstrated that creatine has neuroprotective and antioxidant properties, suggesting benefits for neurodegenerative diseases, including amyotrophic lateral sclerosis and Parkinson's disease, traumatic brain disease, and adult stroke; conditions encompassing hypoxia and excitotoxic‐mediated brain injury (Sullivan 2000; Zhu 2004). A Cochrane review that included three trials assessing creatine for improving amyotrophic lateral sclerosis survival, or for slowing progression, found no clear evidence to support meaningful improvements. Importantly, however, creatine was found to be well tolerated, with no serious adverse effects observed (Pastula 2012). A new Cochrane review will assess the efficacy and safety of creatine when used alone, or as an adjunctive treatment, for Parkinson's disease (Wang 2012).

How the intervention might work

Creatine for fetal neuroprotection

There is currently increasing support for the use of creatine as a therapy for protecting tissues against injury; particularly, there is growing evidence of creatine's potential to act as a neuroprotective agent (Wallimann 2011). One of the primary mechanisms of injury arising from severe hypoxia at birth (particularly for the brain) involves mitochondrial dysfunction, leading to impaired energy metabolism and oxidative stress (Calvert 2005; Wyss 2002). It has been suggested that preservation of ATP through increase of the intracellular pool of creatine and phosphocreatine can protect the brain from such injuries (Beal 2011; Wallimann 1992). In addition to its role as an 'energy buffer' (providing energy in the absence of oxygen), creatine appears to have antioxidant properties, scavenging free radicals (Lawler 2002; Sestili 2006). Creatine has also been shown to improve the recovery of cerebral blood flow following the cessation of a hypoxic episode (Prass 2006).

Hypoxic‐ischaemic models of neonatal brain damage in rodents have provided support for the neuroprotective effects of creatine. Subcutaneous injections of creatine given to neonatal rodents prior to transient severe hypoxia‐ischaemia have been shown to reduce brain oedema (Adcock 2002). Recently, the supplementation of the maternal diet with creatine, from mid‐pregnancy until term, has been shown to not only increase the concentration of creatine and phosphocreatine in rodent fetal tissues, but also to improve survival and postnatal growth of the offspring after an acute hypoxic episode at birth (Ireland 2008). Maternal creatine supplementation during pregnancy has been shown to prevent lipid peroxidation and apoptosis in the brains of rodent offspring following intrapartum hypoxia (Ireland 2011). It has been proposed that creatine's ability to protect mitochondrial function may account for this observed neuroprotective effect (Ireland 2011).

In addition to offering neuroprotection, maternal creatine supplementation has been shown to protect the newborn diaphragm from intrapartum hypoxia‐induced damage (Cannata 2010). Rodent offspring born to mothers who received creatine supplementation from mid‐pregnancy have been shown to be less likely to incur diaphragmatic damage (including muscular atrophy and contractile dysfunction) following hypoxia, as compared with control offspring (Cannata 2010). Most recently, maternal creatine supplementation has been shown to protect the newborn kidney from intrapartum hypoxia‐induced damage. Specifically, creatine given to the mother throughout the second half of pregnancy has been shown to be able to prevent structural damage to the glomeruli and tubules of the kidney of the newborn spiny mouse (Ellery 2013).

Importantly, as with any intervention during pregnancy, the impact for the mother must be considered, along with the impact on the normal development of the fetus. Studies have recently assessed the impact of maternal creatine supplementation from mid‐gestation on the capacity for creatine synthesis and transport in the newborn spiny mouse; encouragingly, long‐term supplementation was not shown to impact on the normal development of these pathways (Dickinson 2013). Similarly, to date, no effects of maternal creatine supplementation on maternal body composition have been observed when creatine‐fed pregnant spiny mice have been compared with control‐fed spiny mice (unpublished observations; Dickinson/Walker laboratory, manuscript under review). While there has been some concern over possible deleterious effects of long‐term, high‐dose creatine supplementation on kidney function, recent work, measuring chromium‐ethylenediamine tetraacetic acid (51‐Cr‐EDTA) clearance, has indicated no negative impact of creatine supplementation on kidney function in human type 2 diabetic patients (Gualano 2011). Studies measuring urine creatinine (as compared with 51‐Cr‐EDTA), as a marker of kidney function, should be interpreted with caution, given that creatinine is a breakdown product of creatine phosphate and creatine in muscle; thus the presence of high urine creatinine would be expected during periods of high creatine consumption, and is not necessarily indicative of kidney damage (Gualano 2011).

In light of the current evidence, it is considered plausible that creatine could protect the human fetal brain against injury associated with hypoxia‐ischaemia, excitotoxicity or oxidative stress, without causing harm to the fetus or the mother. It is important to assess whether maternally administered creatine (at the time of known, suspected, or potential fetal compromise) may offer fetal neuroprotection and may accordingly reduce the risk of cerebral palsy and associated impairments and disabilities arising from fetal brain injury.

Why it is important to do this review

Creatine has been shown to have neuroprotective properties (such as providing cellular energy in the absence of oxygen (Beal 2011; Wallimann 1992), demonstrating antioxidant effects (Lawler 2002; Sestili 2006), and improving cerebral blood flow following hypoxia (Prass 2006)). Animal studies have supported a fetal neuroprotective role for creatine when administered maternally (Ireland 2008; Ireland 2011). It is important to assess whether creatine, when given to pregnant women, can reduce the risk of neurological impairments and disabilities (including cerebral palsy) associated with fetal brain injury, and death, for the preterm or term fetus.

This review will complement the Cochrane review 'Melatonin for women in pregnancy for neuroprotection of the fetus' (Wilkinson 2013), which is assessing melatonin as a novel agent for preterm and/or term fetal neuroprotection, and the Cochrane reviews assessing magnesium sulphate for neuroprotection of the preterm (Doyle 2009) and term fetus (Nguyen 2013).

Objectives

To assess the effects of creatine when used for neuroprotection of the fetus.

Methods

Criteria for considering studies for this review

Types of studies

All published, unpublished, and ongoing randomised trials and quasi‐randomised trials assessing creatine for fetal neuroprotection ‐ although none were identified. We would have included studies reported as abstracts only as well as those with full‐text manuscripts. Studies using a cross‐over or cluster‐randomised design were not eligible for inclusion.

Types of participants

Pregnant women regardless of whether the pregnancy was single or multiple, and regardless of their gestational age. This could include, for example, trials of women with preterm or growth‐restricted fetuses, with chorioamnionitis, with prelabour rupture of membranes, with pre‐eclampsia, or with actual/suspected antenatal/intrapartum fetal distress.

Types of interventions

Trials where creatine was administered to pregnant women, and compared with a placebo or no treatment, or with an alternative agent aimed at providing fetal neuroprotection (e.g. magnesium sulphate or melatonin). We also planned to include trials where creatine was administered to pregnant women where the indication for use was not fetal neuroprotection, where information had been reported on the review's pre‐specified outcomes. We planned to include studies where different regimens for administration of creatine were compared. We planned to include studies regardless of the route (i.e. oral, intramuscular, or intravenous), timing, dose, and duration of creatine administration.

Types of outcome measures

Primary outcomes

We chose primary outcomes that were felt to be most representative of the clinically important measures of effectiveness and safety, including serious outcomes and adverse effects.

For the infant/child

  • Death or any neurosensory disability (at latest time reported) (this combined outcome recognises the potential for competing risks of death or survival with neurological problems)

  • Death (defined as all fetal, neonatal, or later death) (at latest time reported)

  • Neurosensory disability (*any of cerebral palsy, blindness, deafness, developmental delay/intellectual impairment) (at latest time reported)

*Definitions

  • Cerebral palsy: abnormality of tone with motor dysfunction (as diagnosed at 18 months of age or later)

  • Blindness: corrected visual acuity worse than 6/60 in the better eye

  • Deafness: hearing loss requiring amplification or worse

  • Developmental delay/intellectual impairment: a standardised score less than minus one standard deviation (SD) below the mean (or as defined by trialists)

For the mother

  • Any adverse effects severe enough to stop treatment (as defined by trialists)

Secondary outcomes

Secondary outcomes include other measures of effectiveness and safety.

For the fetus/infant

  • Abnormal fetal and umbilical Doppler ultrasound study (as defined by trialists)

  • Fetal death

  • Neonatal death

  • Gestational age at birth

  • Birthweight (absolute and centile)

  • Apgar score (less than seven at five minutes)

  • Active resuscitation via an endotracheal tube at birth

  • Use and duration of respiratory support (mechanical ventilation or continuous positive airways pressure, or both)

  • Intraventricular haemorrhage (including severity – grade one to four) (as defined by trialists)

  • Periventricular leukomalacia (as defined by trialists)

  • Hypoxic ischaemic encephalopathy (as defined by trialists)

  • Neonatal encephalopathy (as defined by trialists)

  • Proven neonatal sepsis (as defined by trialists)

  • Necrotising enterocolitis (as defined by trialists)

  • Abnormal neurological examination (however defined by the trialists, at a point earlier than 18 months of age)

For the mother

  • Side effects and serious adverse events associated with treatment (as reported by individual trialists e.g. renal dysfunction)

  • Women's satisfaction with the treatment (as defined by trialists)

  • Mode of birth (normal vaginal birth, operative vaginal birth, caesarean section), and indication for non‐elective mode of birth

For the infant/child

  • Cerebral palsy (any, and graded as severe: including children who are non‐ambulant and are likely to remain so; moderate: including those children who have substantial limitation of movement; mild: including those children walking with little limitation of movement)

  • Death or cerebral palsy

  • Blindness

  • Deafness

  • Developmental delay/intellectual impairment (classified as severe: a developmental quotient or intelligence quotient less than minus three SD below the mean (or as defined by trialists); moderate: a developmental quotient or intelligence quotient from minus three SD to minus two SD below the mean (or as defined by trialists); mild: a developmental quotient or intelligence quotient from minus two SD to minus one SD below the mean (or as defined by trialists))

  • Major neurosensory disability (defined as any of: moderate or severe cerebral palsy, legal blindness, neurosensory deafness requiring hearing aids, or moderate or severe developmental delay/intellectual impairment)

  • Death or major neurosensory disability

  • Growth assessments at childhood follow‐up (weight, head circumference, length/height)

Use of health services

  • Admission to intensive care unit for the mother

  • Length of postnatal hospitalisation for the women

  • Admission to neonatal intensive care for the infant and length of stay

  • Costs of care for the mother or infant, or both

Search methods for identification of studies

Electronic searches

We contacted the Trials Search Co‐ordinator to search the Cochrane Pregnancy and Childbirth Group's Trials Register (30 November 2014).

The Cochrane Pregnancy and Childbirth Group's Trials Register is maintained by the Trials Search Co‐ordinator and contains trials identified from:

  1. monthly searches of the Cochrane Central Register of Controlled Trials (CENTRAL);

  2. weekly searches of MEDLINE (Ovid);

  3. weekly searches of Embase (Ovid);

  4. handsearches of 30 journals and the proceedings of major conferences;

  5. weekly current awareness alerts for a further 44 journals plus monthly BioMed Central email alerts.

Details of the search strategies for CENTRAL, MEDLINE, and Embase, the list of handsearched journals and conference proceedings, and the list of journals reviewed via the current awareness service can be found in the 'Specialized Register' section within the editorial information about the Cochrane Pregnancy and Childbirth Group.

Trials identified through the searching activities described above are each assigned to a review topic (or topics). The Trials Search Co‐ordinator searches the register for each review using the topic list rather than keywords.

We planned not to apply any language or date restrictions.

Searching other resources

We planned to search reference lists of retrieved studies.

Data collection and analysis

See Appendix 1 for methods of data collection and analysis to be used in future updates of this review.

Results

Description of studies

There were no studies in the Cochrane Pregnancy and Childbirth Group's Trials Register.

Risk of bias in included studies

We found no randomised controlled trials for inclusion in the review.

Effects of interventions

We found no randomised controlled trials for inclusion in the review.

Discussion

We identified no randomised controlled trials assessing the benefits and harms of creatine for women in pregnancy for neuroprotection of the fetus.

Death and neurosensory disabilities, such as cerebral palsy, are serious outcomes after a preterm or term compromised pregnancy/birth, and thus the identification of primary preventative therapies is of crucial importance. Systematic reviews show that maternal administration of corticosteroids for impending preterm birth significantly reduces the risk of neonatal death, respiratory distress, cerebroventricular haemorrhage, and necrotising enterocolitis, and clearly reduces the requirement for neonatal respiratory support and intensive care (Roberts 2006). Antenatal magnesium sulphate administration has also been shown to reduce the risk of cerebral palsy and death when administered to women immediately prior to preterm birth (Doyle 2009). Maternal administration of the xanthine oxidase inhibitor allopurinol is under trial as a means of protecting the fetal brain from hypoxia‐induced oxidative stress (Kaandorp 2010; Kaandorp 2012); and antenatal melatonin is being assessed in pilot studies, for reducing oxidative stress and brain injury in pregnancies complicated by intrauterine growth restriction (ACTRN12612000858897) and pre‐eclampsia (Hobson 2013). While of potential/proven benefit, these treatments may be seen to be initiated 'late', i.e. when preterm birth is imminent or the fetus is already subjected to intrauterine hypoxia. These treatments currently require tertiary level medical care, which may restrict their use to settings with high degrees of obstetric surveillance. In the case of allopurinol, concerns have additionally been raised about its possible interference with normative and hypoxic regulation of the fetal circulation (Kane 2014). Notwithstanding the use of antenatal corticosteroids and magnesium sulphate to lower the risk of brain injury at or near birth (preterm or term), there are currently no accepted treatments that are recommended for use during the second and third trimesters of pregnancy for the purpose of preventing birth‐related hypoxic‐ischaemic encephalopathy.

Clinical trials have shown that long‐term creatine supplementation is well tolerated, slowing the accumulation of glutamate in the brain of early‐onset Huntington's Disease (Bender 2006), and without serious side effects when given over years in patients with Parkinson's Disease (Bender 2005); creatine has also been shown to improve short‐term and long‐term outcomes for children recovering from traumatic brain injury (Sakellaris 2006; Sakellaris 2008). Compelling evidence from recent animal studies suggests that creatine could be a simple, cheap, and effective neuroprotective strategy for the fetus when administered maternally. A recent review, summarising the experimental studies of creatine supplementation during pregnancy to date, concluded that based on current evidence, this treatment should be evaluated as a prophylactic therapy, with the potential to improve fetal and neonatal morbidity and to reduce mortality in high‐risk human pregnancy (through protecting the brain, and possibly preventing damage to other organs) (Dickinson 2014). Creatine readily crosses the placenta in humans (Miller 1974) and animals (Braissant 2005; Ireland 2008), and accumulates in fetal tissues in animals (Ireland 2008). When administered maternally, creatine prevents hypoxia‐induced fetal brain injury (Ireland 2011). The proposed mechanism of action is the maintenance of tissue energy levels, which prevents the activation of apoptotic and lipid peroxidation pathways (Ireland 2011). Creatine/phosphocreatine functions primarily as a spatial and temporal energy buffer, connecting sub‐cellular sites of energy production with sites of energy utilisation at times of high energy demand (Wallimann 1992). In addition to yielding ATP, the dephosphorylation of creatine utilises free protons and ADP, thereby reducing the fall of intracellular pH and aiding in the stabilisation of the mitochondrial membrane potential (Wallimann 1992).

However, in the absence of randomised controlled trial data, uncertainty persists regarding the relative benefits and harms of creatine when given to women in pregnancy for fetal neuroprotection.