Uncovering the complex relationship between pre-eclampsia, preterm birth and cerebral palsy

Hypertensive Disorders of Pregnancy and Risk of Early Brain Abnormalities on Magnetic Resonance Imaging at Term among Infants Born at ≤32 Weeks' Gestational Age

OBJECTIVE

To evaluate the proximal effects of hypertensive disorders of pregnancy (HDP) on a validated measure of brain abnormalities in infants born at ≤32 weeks' gestational age (GA) using magnetic resonance imaging at term-equivalent age.

STUDY DESIGN

In a multisite prospective cohort study, 395 infants born at ≤32 weeks' GA, underwent 3T magnetic resonance imaging scan between 39 and 44 weeks' postmenstrual age. A single neuroradiologist, blinded to clinical history, evaluated the standardized Kidokoro global brain abnormality score as the primary outcome. We classified infants as HDP-exposed by maternal diagnosis of chronic hypertension, gestational hypertension, pre-eclampsia, or eclampsia. Linear regression analysis identified the independent effects of HDP on infant brain abnormalities, adjusting for histologic chorioamnionitis, maternal smoking, antenatal steroids, magnesium sulfate, and infant sex. Mediation analyses quantified the indirect effect of HDP mediated via impaired intrauterine growth and prematurity and remaining direct effects on brain abnormalities.

RESULTS

A total of 170/395 infants (43%) were HDP-exposed. Adjusted multivariable analyses revealed HDP-exposed infants had 27% (95% CI 5%-53%) higher brain abnormality scores than those without HDP exposure (P = .02), primarily driven by increased white matter injury/abnormality scores (P = .01). Mediation analyses showed HDP-induced impaired intrauterine growth significantly (P = .02) contributed to brain abnormality scores (22% of the total effect).

CONCLUSIONS

Maternal hypertension independently increased the risk for early brain injury and/or maturational delays in infants born at ≤32 weeks' GA with an indirect effect of 22% resulting from impaired intrauterine growth. Enhanced prevention/treatment of maternal hypertension may mitigate the risk of infant brain abnormalities and potential neurodevelopmental impairments.

Preterm birth increases cerebral palsy hazards in children of mothers with chronic hypertension in pregnancy

BACKGROUND

Children of mothers with chronic-hypertension in pregnancy have high rates of preterm-birth (<37 weeks of gestation) and small-for-gestational-age (SGA), both of which are risk factors of cerebral palsy (CP). This study investigated the cumulative risks of CP in children exposed to maternal chronic-hypertension vs. other types of hypertensive-disorders-of-pregnancy (HDP), and whether preterm-birth and SGA potentiate the antenatal impact of chronic-hypertension to increase CP hazards.

METHODS

This population-based cohort study enrolled 1,417,373 mother-child pairs with singleton live births between 2004 and 2011 from the Taiwan Maternal and Child Health Database. A total of 19,457 pairs with HDP were identified and propensity-score-matched with 97,285 normotensive controls. Children were followed up for CP outcome until age 6-13 years. HDP were classified into chronic-hypertension, gestational-hypertension, preeclampsia, and preeclampsia-with-chronic-hypertension. Using the normotensive group as the reference, the associations between chronic-hypertension and CP hazard were assessed with adjusted hazard ratios (HR) and 95% confidence intervals (CI) in Cox proportional hazards regression models, and the effects of preterm-birth and SGA on the associations were examined.

RESULTS

The HDP group had higher rates of CP (0.8%) than the normotensive group (0.5%), particularly the subgroup of preeclampsia-with-chronic-hypertension (1.0%), followed by preeclampsia (0.9%), chronic-hypertension (0.7%) and gestational-hypertension (0.6%). Preterm-birth, but not SGA, exerted moderating effects to increase CP risks in children exposed to maternal chronic-hypertension. Before adjustments, chronic-hypertension alone had no substantial contribution to CP hazard (HR 1.35, 95% CI 1.00-1.83), while preeclampsia alone (1.64, 1.28-2.11) or with superimposed-chronic-hypertension (1.83, 1.16-2.89) had significant effects. After including preterm-birth in the multivariable model, the CP hazard for chronic-hypertension alone rather than other types of HDP was raised and became significant (1.56, 1.15-2.12), and the significance remained after stepwise adjustments in the final model (1.74, 1.16-2.60).

CONCLUSIONS

Preterm-birth might potentiate CP hazards in children of mothers with chronic-hypertension in pregnancy.

Neurodevelopmental Disruptions in Children of Preeclamptic Mothers: Pathophysiological Mechanisms and Consequences

Preeclampsia (PE) is a multisystem disorder characterized by elevated blood pressure in the mother, typically occurring after 20 weeks of gestation and posing risks to both maternal and fetal health. PE causes placental changes that can affect the fetus, particularly neurodevelopment. Its key pathophysiological mechanisms encompass hypoxia, vascular and angiogenic dysregulation, inflammation, neuronal and glial alterations, and disruptions in neuronal signaling. Animal models indicate that PE is correlated with neurodevelopmental alterations and cognitive dysfunctions in offspring and in humans, an association between PE and conditions such as cerebral palsy, autism spectrum disorder, attention deficit hyperactivity disorder, and sexual dimorphism has been observed. Considering the relevance for mothers and children, we conducted a narrative literature review to describe the relationships between the pathophysiological mechanisms behind neurodevelopmental alterations in the offspring of PE mothers, along with their potential consequences. Furthermore, we emphasize aspects pertinent to the prevention/treatment of PE in pregnant mothers and alterations observed in their offspring. The present narrative review offers a current, complete, and exhaustive analysis of (i) the pathophysiological mechanisms that can affect neurodevelopment in the children of PE mothers, (ii) the relationship between PE and neurological alterations in offspring, and (iii) the prevention/treatment of PE.

Preterm birth among Pacific Islanders in the United States and the US-affiliated Pacific Islands: A systematic review and meta-analysis

OBJECTIVE

To better understand the epidemiology of preterm birth among Pacific Islanders in the United States and the US-Affiliated Pacific Islands.

METHODS

Systematic searches of MEDLINE, Embase, CINAHL, PsycINFO, two nonindexed regional journals, and gray literature were conducted and finalized in September 2021. Observational studies published since January 2010 that documented preterm birth outcomes among Pacific Islanders in the United States and the US-Affiliated Pacific Islands were eligible for inclusion. Outcomes of interest included preterm birth prevalence, risk compared with white women, and risk factors for preterm birth among Pacific Islanders.

RESULTS

Fourteen of the 3183 screened articles were included in meta-analyses. Random-effects models were used for pooled estimates with 95% confidence intervals. The pooled prevalence of preterm birth among Pacific Islanders was 11.2%, 95% CI: 9.3%-13.6%. Marshallese women had the highest pooled prevalence (20.7%, 95% CI 18.6%-23.0%) among Pacific Islander subgroups. Compared with white women, Pacific Islander women had higher odds of experiencing preterm birth (OR = 1.40, 95% CI: 1.28-1.53). Four risk factors for preterm birth could be explored with the data available: hypertension, diabetes, smoking, and pre-pregnancy body mass index; hypertension and diabetes significantly increased the odds of preterm birth.

CONCLUSIONS

Existing literature suggests that United States Pacific Islanders were more likely to experience preterm birth than white women, although the pooled prevalence varied by Pacific Islander subgroup. Data support the need for disaggregation of Pacific Islanders in future research and argue for examination of subgroup-specific outcomes to address perinatal health disparities.

Preterm birth accelerates the maturation of spontaneous and resting activity in the visual cortex

Prematurity is among the leading risks for poor neurocognitive outcomes. The brains of preterm infants show alterations in structure and electrical activity, but the underlying circuit mechanisms are unclear. To address this, we performed a cross-species study of the electrophysiological activity in the visual cortices of prematurely born infants and mice. Using electroencephalography (EEG) in a sample of healthy preterm (N = 29) and term (N = 28) infants, we found that the maturation of the aperiodic EEG component was accelerated in the preterm cohort, with a significantly flatter 1/f slope when compared to the term infants. The flatter slope was a result of decreased spectral power in the theta and alpha bands and was correlated with the degree of prematurity. To determine the circuit and cellular changes that potentially mediate the changes in 1/f slope after preterm birth, we used in vivo electrophysiology in preterm mice and found that, similar to infants, preterm birth results in a flattened 1/f slope. We analyzed neuronal activity in the visual cortex of preterm (N = 6) and term (N = 9) mice and found suppressed spontaneous firing of neurons. Using immunohistochemistry, we further found an accelerated maturation of inhibitory circuits. In both preterm mice and infants, the functional maturation of the cortex was accelerated, underscoring birth as a critical checkpoint in cortical maturation. Our study points to a potential mechanism of preterm birth-related changes in resting neural activity, highlighting the utility of a cross-species approach in studying the neural circuit mechanisms of preterm birth-related neurodevelopmental conditions.

Predictors of Risk for Cerebral Palsy: A Review

PURPOSE

To identify the earliest predictors of risk for diagnosis of cerebral palsy (CP).

METHODS

A comprehensive literature search was conducted using various databases. The publications were reviewed to identify risk factors for CP from conception to early infancy. Studies were critically appraised with Joanna Briggs Institute guidelines for quality appraisal and evaluated for risk of bias using the Agency for Health Care Research and Quality guidelines.

RESULTS

The initial search yielded 129 studies and 20 studies were included. Forty-seven risk factors for CP were extracted of which several were duplicate terms. The significant risk factors found to be indicative of CP were low birth weight (<1500 g), birth at less than 28 weeks of gestational age, periventricular leukomalacia, grade 3 or 4 intraventricular hemorrhage, preeclampsia, prematurity, an Apgar score of less than 4 at the first minute, birth asphyxia, preterm premature rupture of membrane, and absent fidgety movements.

CONCLUSION

Twenty-three factors were consistently reported as predictors of CP.

Preterm birth accelerates the maturation of spontaneous and resting activity in the visual cortex

Prematurity is among the leading risks for poor neurocognitive outcomes. The brains of preterm infants show alterations in structure and electrical activity, but the underlying circuit mechanisms are unclear. To address this, we performed a cross-species study of the electrophysiological activity in the visual cortices of prematurely born infants and mice. Using electroencephalography (EEG) in a sample of healthy preterm (N=29) and term (N=28) infants, we found that the maturation of the aperiodic EEG component was accelerated in the preterm cohort, with a significantly flatter 1/f slope when compared to the term infants. The flatter slope was a result of decreased spectral power in the theta and alpha bands and was correlated with the degree of prematurity. To determine the circuit and cellular changes that potentially mediate the changes in 1/f slope after preterm birth, we used in vivo electrophysiology in preterm mice and found that, similar to infants, preterm birth results in a flattened 1/f slope. We analyzed neuronal activity in the visual cortex of preterm mice (N=6 preterm and 9 term mice) and found suppressed spontaneous firing of neurons. Using immunohistochemistry, we further found an accelerated maturation of inhibitory circuits. In both preterm mice and infants, the functional maturation of the cortex was accelerated, underscoring birth as a critical checkpoint in cortical maturation. Our study points to a potential mechanism of preterm birth-related changes in resting neural activity, highlighting the utility of a cross-species approach in studying the neural circuit mechanisms of preterm birth-related neurodevelopmental conditions.

Effects of repetitive transcranial magnetic stimulation on motor function and language ability in cerebral palsy: A systematic review and meta-analysis

OBJECTIVE

This review was conducted to assess the quality of the evidence of effectiveness of repetitive transcranial magnetic stimulation (rTMS) in treating motor and language ability of cerebral palsy (CP).

METHOD

Medline, Cochrane library, Web of Science, Embase, PubMed, and CNKI databases were searched up to July 2021 by two independent reviewers. Randomized controlled trials (RCTs) that were published in English and Chinese and met the following criteria were included. The population comprised patients who met the diagnostic criteria for CP. Intervention included the following: comparison about rTMS and sham rTMS or comparison about rTMS combine with other physical therapy and other physical therapy. Outcomes included motor function, as follows: gross motor function measure (GMFM), Gesell Development Diagnosis Scale, fine motor function measure (FMFM), Peabody developmental motor scale, and Modified Ashworth scale. For language ability, sign-significant relation (S-S) was included. Methodological quality was assessed using the Physiotherapy Evidence Database (PEDro) scale.

RESULTS

Finally, 29 studies were included in the meta-analysis. Results of evaluation using the Cochrane Collaborative Network Bias Risk Assessment Scale showed that 19 studies specifically explained randomization, among which two studies described allocation concealment, four studies blinded participants and persons and had low risk of bias, and six studies explained that the assessment of outcome measures was blinded. Significant improvements in motor function were observed. The GMFM of total score was determined by using the random-effect model [I2= 88%; MD = -1.03; 95% CI (-1.35, -0.71); P < 0.0001] and FMFM was determined by using the fixed-effect model [P = 0.40 and I2 = 3%; SMDs = -0.48, 95% CI (-0.65, -0.30); P < 0.01]. For language ability, the language improvement rate was determined using a fixed-effect model [P = 0.88 and I2 = 0%; MD = 0.37, 95% CI (0.23, 0.57); P < 0.01]. According to the PEDro scale, 10 studies had low-quality, four studies had excellent quality, and the other studies had good quality. Using the GRADEpro GDT online tool, we included a total of 31 outcome indicators, as follows: 22 for low quality, seven for moderate quality, and two for very low quality.

CONCLUSION

The rTMS could improve the motor function and language ability of patients with CP. However, rTMS prescriptions varied, and the studies had low sample sizes. Studies using rigorous and standard research designs about prescriptions and large samples are needed to collect sufficient evidence about the effectiveness of using rTMS to treat patients with CP.

The Global Pregnancy Collaboration (CoLab) symposium on short- and long-term outcomes in offspring whose mothers had preeclampsia: A scoping review of clinical evidence

Preeclampsia is a maternal syndrome characterized by the new onset of hypertension after 20 weeks of gestation associated with multisystemic complications leading to high maternal and fetal/neonatal morbidity and mortality. However, sequelae of preeclampsia may extend years after pregnancy in both mothers and their children. In addition to the long-term adverse cardiovascular effects of preeclampsia in the mother, observational studies have reported elevated risk of cardiovascular, metabolic, cerebral and cognitive complications in children born from women with preeclampsia. Less clear is whether the association between maternal preeclampsia and offspring sequelae are causal, or to what degree the associations might be driven by fetal factors including impaired growth and the health of its placenta. Our discussion of these complexities in the 2018 Global Pregnancy Collaboration annual meeting prompted us to write this review. We aimed to summarize the evidence of an association between maternal preeclampsia and neurobehavioral developmental disorders in offspring in hopes of generating greater research interest in this important topic.

Placental dysfunction: The core mechanism for poor neurodevelopmental outcomes in the offspring of preeclampsia pregnancies

Preeclampsia (PE) is a leading condition threatening pregnant women and their offspring. The offspring of PE pregnancies have a high risk of poor neurodevelopmental outcomes and neuropsychological diseases later in life. However, the pathophysiology and pathogenesis of poor neurodevelopment remain undetermined. Abnormal placental functions are at the core of most PE cases, and recent research evidence supports that the placenta plays an important role in fetal brain development. Here, we summarize the relationship between abnormal fetal brain development and placental dysfunction in PE conditions, which include the dysfunction of nutrient and gas-waste exchange, impaired angiogenesis stimulation, abnormal neurotransmitter regulation, disrupted special protectors, and immune disorders. All these factors could lead to poor neurodevelopmental outcomes.

Preeclampsia and Cerebral Palsy in Offspring

The aim of this systematic review and meta-analysis is to examine the association between exposure to preeclampsia during pregnancy and the occurrence of cerebral palsy in offspring. For this reason, the authors searched PubMed/Medline, EMBASE, and Google Scholar databases (end-of-search: 22 November 2021) and identified the most relevant studies. Then, a meta-analysis of all the eligible studies was performed. Subgroup and meta-regression analyses by study design, degree of adjustment, and geographical region were also conducted. A total of 10 studies were finally included, and no statistical significance was noted in the association between preeclampsia and cerebral palsy (pooled OR = 1.16, 95% CI: 0.77–1.74). The subgroup of studies that provided adjusted odds ratios for any variable except for gestational age showed a statistically significant association (pooled OR = 1.62, 95% CI: 1.36–1.93), whereas the association dissipated in studies also adjusting for gestational age (pooled OR = 1.63, 95% CI: 0.48–5.50). In conclusion, it seems that preeclampsia is not associated with cerebral palsy independently of gestational age; however, further research is needed to shed light on this topic.

Calcium supplementation during pregnancy and long‐term offspring outcome: a systematic literature review and meta‐analysis

The World Health Organization currently recommends calcium supplementation for pregnant women, especially those with low calcium intakes, to reduce the risk of hypertension and preeclampsia. We aimed to evaluate the effect of this intervention on selected offspring outcomes. A systematic search was conducted in 11 databases for published randomized controlled trials (RCTs) on the effect of maternal calcium supplementation with or without vitamin D during pregnancy on selected offspring cardiovascular, growth, and metabolic and neurodevelopmental outcomes. Screening of titles and abstracts of 3555 records and full texts of 31 records yielded six RCTs (nine reports, n = 1616). Forest plot analyses were performed if at least two studies presented comparable data on the same outcome. In one study (n = 591), high‐dose calcium supplementation during pregnancy was associated with a decreased risk of offspring high systolic blood pressure at 5–7 years of age (risk ratio = 0.59; 95% confidence interval: 0.39–0.90). The effects of the intervention on offspring growth, metabolic, and neurodevelopmental outcomes remain unknown because of conflicting or insufficient data. High risk of attrition bias decreased the quality of the evidence. Limited available data from RCTs do not provide sufficient evidence to conclude that prenatal calcium supplementation influences offspring health outcomes beyond the newborn period.

Hypertensive disorders in pregnancy and child development at 36 months in the All Our Families prospective cohort study

Hypertensive disorders in pregnancy (HDP) are associated with increased risk of offspring neurodevelopmental disorders, suggesting long-term adverse impacts on fetal brain development. However, the relationship between HDP and deficits in general child development is unclear. Our objective was to assess the association between HDP and motor and cognitive developmental delay in children at 36 months of age. We analyzed data from the All Our Families community-based cohort study (n = 1554). Diagnosis of HDP-gestational or chronic hypertension, preeclampsia, or eclampsia-was measured through medical records. Child development was measured by maternal-report on five domains of the Ages and Stages Questionnaire (ASQ-3). Standardized cut-off scores were used to operationalize binary variables for any delay, motor delay, and cognitive delay. We calculated adjusted risk ratios (aRRs) and 95% confidence intervals (CIs) using logistic regression, sequentially controlling for potential confounders followed by factors suspected to lie on the causal pathway. Overall, 8.0% of women had HDP and hypertension-exposed children had higher prevalence of delay than unexposed children. Hypertension-exposed children had elevated risk for developmental delay, but CIs crossed the null. The aRRs quantifying the fully adjusted effect of HDP on child development were 1.19 (95% CI 0.92, 1.53) for any delay, 1.18 (95% CI 0.86, 1.61) for motor delay, and 1.24 (95% CI 0.83, 1.85) for cognitive delay. We did not find a statistically significant association between HDP and developmental delay. Confidence intervals suggest that children exposed to HDP in utero have either similar or slightly elevated risk of any, motor, and cognitive delay at 36 months after controlling for maternal and obstetric characteristics. The observed direction of association aligns with evidence of biological mechanisms whereby hypertensive pathology can disrupt fetal neurodevelopment; however, more evidence is needed. Findings may have implications for early developmental monitoring and intervention following prenatal hypertension exposure.

Clinical outcomes of hypertensive disorders in pregnancy in the offspring during perinatal period, childhood, and adolescence

Hypertensive disorders during pregnancy (HDP) could have significant clinical impact not only on the mother's, but also on the offspring's health. The clinical impact of HDP may be evident early in the perinatal period or during childhood and adolescence. The cardiovascular system seems to be primarily affected with higher rates of congenital heart defects reported from cohort studies in the offspring of mothers with HDP. HDP are associated with alterations in cardiac and vascular structure and higher BP during childhood. HDP may also affect brain development and could result in increased prevalence of adverse cognitive outcomes and neuropsychiatric disorders in children and adolescents. The kidney, immune, endocrine, and gastrointestinal system abnormalities could also have their origin in exposure to HDP. The aim of this narrative review is to examine the clinical impact of HDP on the offspring with a focus on the perinatal period, childhood, and adolescence.

Preeclampsia and Neurodevelopmental Outcomes: Potential Pathogenic Roles for Inflammation and Oxidative Stress?

Preeclampsia (PE) is a common and serious hypertensive disorder of pregnancy that occurs in approximately 3-5% of first-time pregnancies and is a well-known leading cause of maternal and neonatal mortality and morbidity. In recent years, there has been accumulating evidence that in utero exposure to PE acts as an environmental risk factor for various neurodevelopmental disorders, particularly autism spectrum disorder and ADHD. At present, the mechanism(s) mediating this relationship are uncertain. In this review, we outline the most recent evidence implicating a causal role for PE exposure in the aetiology of various neurodevelopmental disorders and provide a novel interpretation of neuroanatomical alterations in PE-exposed offspring and how these relate to their sub-optimal neurodevelopmental trajectory. We then postulate that inflammation and oxidative stress, two prominent features of the pathophysiology of PE, are likely to play a major role in mediating this association. The increased inflammation in the maternal circulation, placenta and fetal circulation in PE expose the offspring to both prenatal maternal immune activation-a risk factor for neurodevelopmental disorders, which has been well-characterised in animal models-and directly higher concentrations of pro-inflammatory cytokines, which adversely affect neuronal development. Similarly, the exaggerated oxidative stress in the mother, placenta and foetus induces the placenta to secrete factors deleterious to neurons, and exposes the fetal brain to directly elevated oxidative stress and thus adversely affects neurodevelopmental processes. Finally, we describe the interplay between inflammation and oxidative stress in PE, and how both systems interact to potentially alter neurodevelopmental trajectory in exposed offspring.

Association of Preeclampsia in Term Births With Neurodevelopmental Disorders in Offspring

IMPORTANCE

Preeclampsia during pregnancy has been linked to an increased risk of cerebral palsy in offspring. Less is known about the role of preeclampsia in other neurodevelopmental disorders.

OBJECTIVE

To determine the association between preeclampsia and a range of adverse neurodevelopmental outcomes in offspring after excluding preterm births.

DESIGN, SETTING, AND PARTICIPANTS

This prospective, population-based cohort study included singleton children born at term from January 1, 1991, through December 31, 2009, and followed up through December 31, 2014 (to 5 years of age), using Norway's Medical Birth Registry and linked to other demographic, social, and health information by Statistics Norway. Data were analyzed from May 30, 2018, to November 17, 2019.

EXPOSURES

Maternal preeclampsia.

MAIN OUTCOMES AND MEASURES

Associations between preeclampsia in term pregnancies and cerebral palsy, attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), epilepsy, intellectual disability, and vision or hearing loss using multivariable logistic regression.

RESULTS

The cohort consisted of 980 560 children born at term (48.8% female and 51.2% male; mean [SD] gestational age, 39.8 [1.4] weeks) with a mean (SD) follow-up of 14.0 (5.6) years. Among these children, 28 068 (2.9%) were exposed to preeclampsia. Exposed children were at increased risk of ADHD (adjusted odds ratio [OR], 1.18; 95% CI, 1.05-1.33), ASD (adjusted OR, 1.29; 95% CI, 1.08-1.54), epilepsy (adjusted OR, 1.50; 95% CI, 1.16-1.93), and intellectual disability (adjusted OR, 1.50; 95% CI, 1.13-1.97); there was also an apparent association between preeclampsia exposure and cerebral palsy (adjusted OR, 1.30; 95% CI, 0.94-1.80).

CONCLUSIONS AND RELEVANCE

Preeclampsia is a well-established threat to the mother. Other than the hazards associated with preterm delivery, the risks to offspring from preeclampsia are usually regarded as less important. This study's findings suggest that preeclampsia at term may have lasting effects on neurodevelopment of the child.

Association between maternal hypertensive disorders of pregnancy and child neurodevelopment at 3 years of age: a retrospective cohort study

Hypertensive disorders of pregnancy (HDP) affect up to 10% of women during pregnancy and influence child neurodevelopment, including mental and motor function. We assessed whether HDP, including gestational hypertension, preeclampsia, superimposed preeclampsia, and eclampsia, correlate with motor and mental developmental abnormalities in 3-year-old children, using data obtained between April 2004 and March 2013 through a mandatory population-based health checkup of mothers and children in Kobe city, Japan. The primary outcome was motor and mental developmental abnormalities at 3 years of age; parental-reported questionnaires and physician's medical examinations were evaluated. The association between maternal HDP and child neurodevelopmental abnormality was evaluated using a logistic regression model. Of the 43,854 participating children, 1120 were born to women with HDP and 42,734 were born to women without HDP. The prevalence of motor developmental abnormality was 1.7% in the exposed group and 0.95% in the control group; the prevalence of mental developmental abnormality was 2.41% in the exposed group and 1.22% in the control group. Children born to mothers with HDP did not have an increased risk of motor developmental abnormality at the age of 3 years [adjusted odds ratio (OR) 1.17, 95% confidence interval 0.72-1.91], but had an increased risk of mental developmental abnormality (adjusted OR 1.80, 95% confidence interval 1.21-2.69). Maternal HDP were associated with mental development abnormality in 3-year-old children. These findings may be clinically relevant; mental abnormality in children born to women with HDP could be detected during early stages, which would facilitate early intervention.

Neurodevelopmental Outcomes of Prenatal Preeclampsia Exposure

Preeclampsia is a dangerous hypertensive disorder of pregnancy with known links to negative child health outcomes. Here, we review epidemiological and basic neuroscience work from the past several decades linking prenatal preeclampsia to altered neurodevelopment. This work demonstrates increased rates of neuropsychiatric disorders [e.g., increased autism spectrum disorder, attention deficit hyperactivity disorder (ADHD)] in children of preeclamptic pregnancies, as well as increased rates of cognitive impairments [e.g., decreased intelligence quotient (IQ), academic performance] and neurological disease (e.g., stroke and epilepsy). We also review findings from multiple animal models of preeclampsia. Manipulation of key clinical preeclampsia processes in these models (e.g., placental hypoxia, immune dysfunction, angiogenesis, oxidative stress) causes various disruptions in offspring, including ones in white matter/glia, glucocorticoid receptors, neuroimmune outcomes, cerebrovascular structure, and cognition/behavior. This animal work implicates potentially high-yield targets that may be leveraged in the future for clinical application.

Rehabilitation treatment of spastic cerebral palsy with radial extracorporeal shock wave therapy and rehabilitation therapy

This aims to investigate the effect of combined use of radial extracorporeal shock wave therapy (rESWT) and conventional rehabilitation therapy on postoperative rehabilitation of children with spastic cerebral palsy.Children with spastic cerebral palsy 6 weeks after multistage surgery were randomly divided into treatment group (received rESWT and conventional rehabilitation therapy) and control group (received conventional rehabilitation only). Before treatment, 2 weeks and 1 month after treatment, the Gross Motor Function Measure (GMFM), modified Ashworth Scale (MAS) of the hamstrings and triceps, plantar area and plantar pressure were examined for efficacy assessment.A total of 82 children with spastic cerebral palsy were recruited, including 43 children in treatment group and 39 children in control group. There was no significant difference in the age, MAS score, and GMFM score between the 2 groups before treatment. There were statistically significant differences between the 2 groups at 2 weeks and 4 weeks after treatment, including the MAS score, GMFM score, plantar area and plantar pressure (P < .05). Within groups, there were also significant differences at different times (P < .05).The rESWT combined with rehabilitation can quickly and effectively relieve paralysis of lower extremities, reduce the tension of hamstrings and calf muscles, relieve muscle spasm, and rapidly improve limb function in children with spastic cerebral palsy.

Directed acyclic graphs: a tool for causal studies in paediatrics

Many paediatric clinical research studies, whether observational or interventional, have as an eventual aim the identification or quantification of causal relationships. One might ask: does screen time influence childhood obesity? Could overuse of paracetamol in infancy cause wheeze? How does breastfeeding affect later cognitive outcomes? In this review, we present causal directed acyclic graphs (DAGs) to a paediatric audience. DAGs are a graphical tool which provide a way to visually represent and better understand the key concepts of exposure, outcome, causation, confounding, and bias. We use clinical examples, including those outlined above, framed in the language of DAGs, to demonstrate their potential applications. We show how DAGs can be most useful in identifying confounding and sources of bias, demonstrating inappropriate statistical adjustments for presumed biases, and understanding threats to validity in randomised controlled trials. We believe that a familiarity with DAGs, and the concepts underlying them, will be of benefit both to the researchers planning studies, and practising clinicians interpreting them.

Maternal pre-eclampsia and long-term offspring health: Is there a shadow cast?

Pre-eclampsia is a common pregnancy disorder with important short-term complications for mother and baby. Evidence suggests pre-eclampsia also has implications for the mother beyond pregnancy, as well as long-term effects on offspring health. Limited research has linked pre-eclampsia with changes in offspring blood pressure, BMI, and stroke risk. Underpinning mechanisms are poorly understood, but developmental programming may be involved. Research in this area has been hindered by difficulties in defining pre-eclampsia and problems with study design. Further targeted evaluation through to adulthood is required to determine the long-term impact of pre-eclampsia on offspring disease risk and how this develops.

Confounding, causality, and confusion: the role of intermediate variables in interpreting observational studies in obstetrics

Prospective and retrospective cohorts and case-control studies are some of the most important study designs in epidemiology because, under certain assumptions, they can mimic a randomized trial when done well. These assumptions include, but are not limited to, properly accounting for 2 important sources of bias: confounding and selection bias. While not adjusting the causal association for an intermediate variable will yield an unbiased estimate of the exposure-outcome's total causal effect, it is often that obstetricians will want to adjust for an intermediate variable to assess if the intermediate is the underlying driver of the association. Such a practice must be weighed in light of the underlying research question and whether such an adjustment is necessary should be carefully considered. Gestational age is, by far, the most commonly encountered variable in obstetrics that is often mislabeled as a confounder when, in fact, it may be an intermediate. If, indeed, gestational age is an intermediate but if mistakenly labeled as a confounding variable and consequently adjusted in an analysis, the conclusions can be unexpected. The implications of this overadjustment of an intermediate as though it were a confounder can render an otherwise persuasive study downright meaningless. This commentary provides an exposition of confounding bias, collider stratification, and selection biases, with applications in obstetrics and perinatal epidemiology.

Hypertensive disorders during pregnancy and health outcomes in the offspring: a systematic review

The hypertensive disorders of pregnancy complicate up to 10% of pregnancies worldwide and are a leading cause of maternal, foetal, and neonatal morbidity and mortality. The aim of this study was to present an overview of recent studies addressing offspring's medium and long-term health outcomes after intrauterine exposure to maternal hypertension. A search on PubMed/MEDLINE and Bireme databases was conducted to identify observational studies that reported any offspring outcome measured after the 6th month of life. The search was limited to studies published after May 2008. Forty-five articles were included and categorized into four groups of outcomes: cardiovascular, immune, metabolic and behavioural/neurological effects. According to our findings, hypertensive disorders of pregnancy had an overall negative impact on offspring's cardiovascular, immune and neurological health, although not all parameters analysed in each group had consistent results among studies. The most prominent and reliable associations were verified between gestational hypertension and higher offspring's blood pressure and between preeclampsia and offspring's lower cognitive functioning. In the metabolic outcomes, body composition had conflicting results among papers, while all studies that examined blood biomarkers showed no evidence that preeclampsia or gestational hypertension could be associated with an alteration of this metabolic outcomes. Most included studies were highly heterogeneous regarding the measure of outcomes and covariables used for adjustments. Future studies should consider using the same protocols and cut-off points already published so that results can be better compared and summarized. This review was registered in PROSPERO.

REGISTRATION NUMBER

CRD42015020838.

Cerebral palsy and perinatal mortality after pregnancy-induced hypertension across the gestational age spectrum: observations of a reconstructed total population cohort

AIM

Pregnancy-induced hypertension/pre-eclampsia (PIH/PE) is associated with cerebral palsy (CP) in term births but if sufficiently severe to necessitate preterm delivery predicts a lower risk of CP than observed in gestational peers. We investigated whether this apparent 'protection' was attributable to inappropriately chosen comparison groups and/or an increased risk of perinatal death.

METHOD

Perinatal information was collected from medical records of children with CP, individually matched neonatal survivors without CP, and representative samples of perinatal deaths of Western Australian birth cohorts from 1980 to 1995. Compared with these data, the sensitivity of statutorily collected PIH/PE data was assessed for each outcome group. Using these sensitivities, the estimated risks of death and CP in births to all women with and without PIH/PE were compared.

RESULTS

Sensitivity of statutory PIH/PE data decreased with increasingly poor outcome. Reconstructed cohorts showed that PIH/PE increased the risks both of CP and of perinatal death in births at lower gestations except in births <27 weeks, where the risk of perinatal death only increased greatly.

INTERPRETATION

PIH/PE does not protect against poor outcome at any gestational age. Previously reported protective effects originate from inappropriate control for gestational age and not from higher gestation-specific perinatal mortality.

Relevant Obstetric Factors for Cerebral Palsy: From the Nationwide Obstetric Compensation System in Japan

Objective

The aim of this study was to identify the relevant obstetric factors for cerebral palsy (CP) after 33 weeks’ gestation in Japan.

Study design

This retrospective case cohort study (1:100 cases and controls) used a Japanese national CP registry. Obstetric characteristics and clinical course were compared between CP cases in the Japan Obstetric Compensation System for Cerebral Palsy database and controls in the perinatal database of the Japan Society of Obstetrics and Gynecology born as live singleton infants between 2009 and 2011 with a birth weight ≥ 2,000 g and gestation ≥ 33 weeks.

Results

One hundred and seventy-five CP cases and 17,475 controls were assessed. Major relevant single factors for CP were placental abnormalities (31%), umbilical cord abnormalities (15%), maternal complications (10%), and neonatal complications (1%). A multivariate regression model demonstrated that obstetric variables associated with CP were acute delivery due to non-reassuring fetal status (relative risk [RR]: 37.182, 95% confidence interval [CI]: 20.028–69.032), uterine rupture (RR: 24.770, 95% CI: 6.006–102.160), placental abruption (RR: 20.891, 95% CI: 11.817–36.934), and preterm labor (RR: 3.153, 95% CI: 2.024–4.911), whereas protective factors were head presentation (RR: 0.199, 95% CI: 0.088–0.450) and elective cesarean section (RR: 0.236, 95% CI: 0.067–0.828).

Conclusion

CP after 33 weeks’ gestation in the recently reported cases in Japan was strongly associated with acute delivery due to non-reassuring fetal status, uterine rupture, and placental abruption.

Controlled direct effects of preeclampsia on neonatal health after accounting for mediation by preterm birth

BACKGROUND

Preeclampsia is characterized by alterations in angiogenic factors that may increase neonatal morbidity independent of preterm birth.

METHODS

We estimated the controlled direct effect of preeclampsia on neonatal outcomes independent of preterm birth among 200,103 normotensive and 10,507 preeclamptic singleton pregnancies in the Consortium on Safe Labor (2002-2008). Marginal structural models with stabilized inverse probability weights accounted for potential confounders in the pathway from preeclampsia to preterm birth to neonatal outcomes, including mediator-outcome confounders related to preeclampsia status, such as cesarean delivery. Controlled direct effects of preeclampsia on perinatal mortality, small for gestational age (SGA), neonatal intensive care unit (NICU) admission, respiratory distress syndrome, transient tachypnea of the newborn, anemia, apnea, asphyxia, peri- or intraventricular hemorrhage, and cardiomyopathy were estimated for the hypothesized intervention of term delivery for all infants.

RESULTS

When delivery was set at ≥37 weeks, preeclampsia increased the odds of perinatal mortality (odds ratio = 2.2 [95% confidence interval = 1.1-4.5], SGA = (1.9 [1.8-2.1]), NICU admission (1.9 [1.7-2.1]), respiratory distress syndrome (2.8 [2.0-3.7], transient tachypnea of the newborn (1.6 [1.3-1.9]), apnea (2.2 [1.6-3.1]), asphyxia (2.7 [1.5-4.9]), and peri- or intraventricular hemorrhage (3.2 [1.4-7.7]). No direct effect of preeclampsia at term was observed for anemia or cardiomyopathy. Our results appear robust in the presence of moderate confounding, and restriction to severe preeclampsia yielded similar findings.

CONCLUSION

Preeclampsia was directly associated with adverse neonatal outcomes beyond morbidity mediated by preterm birth. Although severe neonatal outcomes were less common at later gestational ages, marginal structural models suggested elevated neonatal risk due to preeclampsia even if it was possible to deliver all infants at term.

Fetuses-at-risk, to avoid paradoxical associations at early gestational ages: extension to preterm infant mortality

BACKGROUND

Fetuses-at-risk denominators are commonly used in research on preterm stillbirth, but applications to postnatal outcomes such as preterm infant mortality are controversial. We evaluated whether biased associations between maternal risk factors and preterm infant mortality caused by stratification by preterm birth could be avoided using fetuses-at-risk risk ratios.

METHODS

Data included 3 277 570 births drawn from the linked live birth-death file for Canada from 1990 through 2005. We used maternal age as the risk factor, and estimated the association with stillbirth, early neonatal, late neonatal and postneonatal mortality by gestational interval (22-24, 25-27, 28-31, 32-36, ≥37 weeks). Models were run using (i) log-binomial regression stratified by preterm gestational age, and (ii) unstratified log-binomial regression using fetuses-at-risk denominators.

RESULTS

Extremes of maternal age were associated with higher mortality among term births. Among preterm births, the stratified model suggested a protective, null or attenuated association of extremes of maternal age with stillbirth, early, late and post neonatal mortality. The unstratified fetuses-at-risk model, however, resulted in the expected higher risk of mortality at extremes of maternal age for all outcomes.

CONCLUSIONS

Fetuses-at-risk regression can avoid paradoxical associations between maternal exposures and mortality of infants born early in gestation, caused by preterm birth stratification bias. The fetuses-at-risk approach can be extended through the first year of life, or potentially beyond, depending on the outcome and presence of unmeasured confounders associated with preterm birth.

Risk of cerebral palsy in relation to pregnancy disorders and preterm birth: a national cohort study

AIM

To assess the risk of developing cerebral palsy in relation to pregnancy disorders and preterm birth.

METHOD

By linking the Medical Birth Registry of Norway to other national registries, we identified all live births in Norway from 1967 through to 2001. Risks of cerebral palsy (CP) after preterm delivery and pregnancy disorders were estimated in different gestational age groups.

RESULT

In total, 1 764 509 children delivered at 23 to 43 weeks' gestation were included. The prevalence of CP was 1.8 per 1000 births. Absolute risk of CP was 8.5% among children born at 23 to 27 weeks' gestation, 5.6% at 28 to 30 weeks, 2.0% at 31 to 33 weeks, 0.4% at 34 to 36 weeks, and 0.1% thereafter. Placental abruption, chorioamnionitis, prolonged rupture of membranes, intrauterine growth restriction, pre-eclampsia, multiple births, placenta previa, bleeding, cervical conization, and congenital malformation were all associated with CP. Before 32 weeks' gestation, absolute risk of CP was highest with chorioamnionitis (9.1%) and lowest with pre-eclampsia (3.1%). Among those born after 31 weeks, the absolute risk of CP was more consistently (but also more slightly) increased with a recorded pregnancy disorder.

INTERPRETATION

Early delivery and pregnancy disorders were both strong risk factors for CP. The added risks with recorded pregnancy disorders varied within categories of gestational age.

Gestational age-dependent risk factors for preterm birth: associations with maternal education and age early in gestation

OBJECTIVES

Preterm birth (PTB) before 37 weeks can occur over a wide range of gestational ages, but few studies have assessed if associations between risk factors and PTB vary over the duration of gestation. We sought to evaluate if associations between two major risk factors (maternal education and age) and PTB depend on gestational age at delivery.

STUDY DESIGN

We estimated hazard ratios of PTB for education and age in a time-to-event analysis using a retrospective cohort of 223,756 live singleton births from the province of Québec, Canada for the years 2001-2005. Differences in hazards of maternal education and age with PTB were assessed over gestational age in a Cox proportional hazards model using linear and nonlinear time interaction terms, adjusting for maternal characteristics.

RESULTS

Associations of PTB with lower (vs. higher) education and older (vs. younger) age strengthened progressively at earlier gestational ages, such that the risk of PTB for maternal education and age was not constant over the course of gestation.

CONCLUSIONS

Associations of PTB with risk factors such as maternal low education and older age may be stronger early in gestation. Models that capture the time-dependent nature of PTB may be useful when the goal is to assess associations at low gestational ages, and to avoid masked or biased associations early in gestation.

Cesarean delivery and cerebral palsy: a systematic review and meta-analysis

OBJECTIVE

To examine the association of cesarean delivery and cerebral palsy using a systematic literature review and meta-analysis.

DATA SOURCES

MEDLINE, Embase, and ClinicalTrials.gov were systematically searched for articles relating to cerebral palsy and cesarean delivery from inception until December 2012. Only articles reporting confirmed cases of cerebral palsy were included. Meta-analysis was used to assess combined results and also the following subgroups: emergency cesarean; elective cesarean; term delivery; preterm delivery; and delivery of breech-presenting newborns.

METHODS OF STUDY SELECTION

Literature searches returned 1,874 articles with 58 considered in full. Studies were selected if they reported an endpoint of cerebral palsy, an intervention or risk of cesarean delivery, were in English, and gave sufficient details to perform meta-analysis.

TABULATION, INTEGRATION, AND RESULTS

Nine case-control and four cohort studies were included in the overall analysis. Meta-analysis showed no overall association of cesarean delivery with cerebral palsy (odds ratio [OR] 1.29; 95% confidence interval [CI] 0.92-1.79; 3,810 case group participants and 1,692,580 control group participants). Emergency cesarean delivery was associated with increased risk of cerebral palsy (OR 2.17; 95% CI 1.58-2.98), whereas there was no significant association between elective cesarean delivery and cerebral palsy (OR 0.81; 95% CI 0.41-1.58). Any type of cesarean delivery (elective or emergency) for term newborns was associated with cerebral palsy (OR 1.6; 95% CI 1.05-2.44), whereas there was no association between any type of cesarean delivery and cerebral palsy in preterm newborns (OR 0.81; 95% CI 0.47-1.40). Cesarean delivery did not significantly modify cerebral palsy risk for breech-presenting newborns (OR 0.51; 95% CI 0.13-2.05).

CONCLUSION

A review of the literature does not support the use of elective or emergency cesarean delivery to prevent cerebral palsy.

Contemporary clinical management of the cerebral complications of preeclampsia

The neurological complications of preeclampsia and eclampsia are responsible for a major proportion of the morbidity and mortality arising from these conditions, for women and their infants alike. This paper outlines the evidence base for contemporary management principles pertaining to the neurological sequelae of preeclampsia, primarily from the maternal perspective, but with consideration of fetal and neonatal aspects as well. It concludes with a discussion regarding future directions in the management of this potentially lethal condition.

Congenital cerebral palsy, child sex and parent cardiovascular risk

Objective

Genes associated with cardiovascular disease may also be risk factors for congenital cerebral palsy (CP) and these associations may be modified by sex, since there is an increased risk of CP in male children. We investigated the association between CP of the child with cardiovascular disease in parents, taking sex of the child into consideration.

Methods

All parents of non-adopted singletons born in Denmark between 1973 and 2003 were included. Parents of a child with CP, confirmed by the Danish National CP registry, were considered exposed. Cox proportional hazards regressions were used to model risk of cardiovascular outcomes for exposed parents compared to all other parents beginning at the child’s 10^th birthday.

Results

We identified 733,730 mothers and 666,652 fathers among whom 1,592 and 1,484, respectively, had a child with CP. The mean age for mothers at end of follow up was 50±8 years. After adjustment for maternal age, parental education, child’s sex, child’s residence, child being small for gestational age and maternal hypertensive disorder during pregnancy, mothers of CP male children had an excess risk of cardiovascular disease (HR: 1.52, 95% CI: 1.16-2.00), attributable mostly to an increased incidence of hypertension and cerebrovascular disease. After additional adjustment for preterm birth, the association was markedly attenuated for cardiovascular disease (1.34, 95%CI: 1.02 - 1.76), became nonsignificant for hypertension, but remained significant for cerebrovascular disease (HR: 2.73, 95% CI: 1.45- 5.12). There was no increased risk of cardiovascular events in mothers of female CP children, or fathers of CP children of any sex.

Conclusions

Women that have a male child with CP are at increased risk for premature cardiovascular disease. Part of this association may be related to risk factors for preterm births.

Movement outcomes of infants born moderate and late preterm

AIM

To investigate whether children born between 32 and 36 weeks of gestation have an increased risk of motor coordination difficulties or cerebral palsy (CP) at age 7 years.

METHODS

A cohort study based on the Avon Longitudinal Study of Parents and Children (ALSPAC). The primary outcomes were poor motor coordination, defined as an ALSPAC coordination test score <5th centile or the presence of CP. Exposure groups were defined as moderate or late preterm (32-36 weeks of gestation) or term (37-42 weeks). Regression models were used to investigate the association between gestational age and outcomes. Multiple imputation was used to account for missing covariate data.

RESULTS

In the fully adjusted model, there was strong evidence that children born at moderate or late preterm had worse coordination (OR 1.41 (1.14-1.74)) and higher risk of CP (OR 6.38 (2.28-17.76)) than term peers. However, restricting the analysis to well-grown infants born vaginally, in good condition, the associations attenuated substantially.

CONCLUSIONS

Moderate or late preterm infants were at increased risk of developing coordination problems and cerebral palsy. After restricting the analysis to 'well' infants the associations of gestation with the coordination measures and CP reduced substantially, suggesting that antenatal, intrapartum and neonatal causal pathways are likely to be involved.

Mediators of the association between pre-eclampsia and cerebral palsy: population based cohort study

OBJECTIVE

To test the hypothesis that pre-eclampsia is a risk factor for cerebral palsy mediated through preterm birth and being born small for gestational age.

DESIGN

Population based cohort study.

SETTING

Clinical data from the Norwegian Cerebral Palsy Registry were linked with perinatal data prospectively recorded by the Medical Birth Registry of Norway.

PARTICIPANTS

All singleton babies who survived the neonatal period during 1996-2006 (849 children with cerebral palsy and 616,658 control children).

MAIN OUTCOME MEASURES

Cerebral palsy and cerebral palsy subtypes.

RESULTS

Children exposed to pre-eclampsia had an excess risk of cerebral palsy (unadjusted odds ratio 2.5, 95% confidence interval 2.0 to 3.2) compared with unexposed children. Among children born at term (≥ 37 weeks), exposure to pre-eclampsia was not associated with an excess risk of cerebral palsy in babies not born small for gestational age (1.2, 0.7 to 2.0), whereas children exposed to pre-eclampsia and born small for gestational age had a significantly increased risk of cerebral palsy (3.2, 1.5 to 6.7). Non-small for gestational age babies born very preterm (<32 weeks) and exposed to pre-eclampsia had a reduced risk of cerebral palsy compared with unexposed children born at the same gestational age (0.5, 0.3 to 0.8), although the risk was not statistically significantly reduced among children exposed to pre-eclampsia and born small for gestational age (0.7, 0.4 to 1.3). Exposure to pre-eclampsia was not associated with a specific cerebral palsy subtype.

CONCLUSIONS

Exposure to pre-eclampsia was associated with an increased risk of cerebral palsy, and this association was mediated through the children being born preterm or small for gestational age, or both. Among children born at term, pre-eclampsia was a risk factor for cerebral palsy only when the children were small for gestational age.

A TIR domain receptor-associated protein (TIRAP) variant SNP (rs8177374) confers protection against premature birth

OBJECTIVE

To investigate whether single nucleotide polymorphisms (SNPs) in genes encoding the Toll-like receptor (TLR) signaling pathway modulate susceptibility to preterm birth (PTB).

STUDY DESIGN

Prospective case-control study examining the contribution of nine TLR SNPs to PTB (<37 weeks) and PTB <32 weeks. Genotyping was done on neonatal blood using a multiplexed single-base extension assay. Chi-square test, Fischer's exact test and classification trees were used for data analysis.

RESULT

Preterm infants (n=177) were more likely to be African American (P=0.02), and were more likely to be born to mothers who smoked (P=0.007), had pregnancy-induced hypertension (PIH; P=0.002) and placental abruption (P=0.0004) when compared with term infants (n=146). The TLR2, TLR4, TLR5, TLR9, nuclear factor-kappa B1 (NFκB1), NFκBIA and IRAK1 variants were not associated with PTB whereas the TIR domain receptor-associated protein (TIRAP) variant was more prevalent in term infants when compared with preterm infants born <32 weeks (P=0.004). PTB <32 weeks was more prevalent in infants without the TIRAP variant whose mothers had PIH and did not smoke (P=0.001). Presence of the TIRAP variant protected against PTB <32 weeks (P=0.015) in Caucasian infants.

CONCLUSION

In our study, a TLR pathway adapter variant (TIRAP (rs8177374)) protected against PTB<32 weeks, supporting our hypothesis that genetic variation in the innate immune signaling pathway contributes to altered risk of PTB.

Maternal hypertension and intrapartum fever are associated with increased risk of ischemic stroke during infancy

AIM

To examine maternal hypertension, diabetes, and intrapartum fever as potential risk factors for ischemic stroke in infants.

METHOD

We conducted a retrospective cohort study of 226,117 children born from January 2000 to December 2007 who were enrolled in the South Carolina Medicaid program. We linked maternal and child Medicaid billing records and birth certificate data. Children with ischemic stroke were identified based on the International Classification of Diseases, Ninth Revision (ICD-9), code 434 in the child's billing data. Independent variables and covariates were identified using ICD-9 codes and birth certificate data. We modeled the odds of ischemic stroke diagnosis in infants, either before 30 days of life or before 365 days.

RESULTS

Forty-three children were diagnosed with ischemic stroke before 30 days and 161 before 365 days. Maternal hypertension (odds ratio 2.31 before 30 d) and intrapartum fever (odds ratio 3.36 <30 d) were significantly associated with odds of ischemic stroke before 30 days and before 365 days; maternal diabetes was not.

INTERPRETATION

Maternal hypertension and intrapartum fever appear to be risk factors for ischemic stroke in infants. Additional research is needed to determine the mechanism(s) underlying these associations and to develop effective preventive methods for high-risk infants.

Conditioning on intermediates in perinatal epidemiology

It is common practice in perinatal epidemiology to calculate gestational-age-specific or birth-weight-specific associations between an exposure and a perinatal outcome. Gestational age or birth weight, for example, might lie on a pathway from the exposure to the outcome. This practice of conditioning on a potential intermediate has come under critique for various reasons. First, if one is interested in assessing the overall effect of an exposure on an outcome, it is not necessary to stratify, and indeed, it is important not to stratify, on an intermediate. Second, if one does condition on an intermediate, to try to obtain what might conceived of as a "direct effect" of the exposure on the outcome, then various biases and paradoxical results can arise. It is now well documented theoretically and empirically that, when there is an unmeasured common cause of the intermediate and the outcome, associations adjusted for the intermediate are subject to bias. In this paper, we propose 3 approaches to facilitate valid inference when effects conditional on an intermediate are in view. These 3 approaches correspond to (i) conditioning on the predicted risk of the intermediate, (ii) conditioning on the intermediate itself in conjunction with sensitivity analysis, and (iii) conditioning on the subgroup of individuals for whom the intermediate would occur irrespective of the exposure received. The second and third approaches both require sensitivity analysis, and they result in a range of estimates. Each of the 3 approaches can be used to resolve the "birth-weight paradox" that exposures such as maternal smoking seem to have a protective effect among low-birth-weight infants. The various methodologic approaches described in this paper are applicable to a number of similar settings in perinatal epidemiology.

Educational inequalities in preterm and term small-for-gestational-age birth over time

PURPOSE

Time trends in educational inequalities in small-for-gestational-age (SGA) birth are important to evaluate for policy, especially at preterm gestational ages when morbidity and mortality are typically greater. We evaluated educational inequalities in preterm and term SGA birth over time, accounting for potential bias at preterm gestational ages.

METHODS

Data included 2,204,056 singleton live births from 25 to 43 gestational weeks, 1981 to 2007. We estimated prevalence ratios (PR) and percent prevalence differences (PPD) of preterm and term SGA birth for a continuous education score, accounting for maternal characteristics. Sensitivity analyses included correction for misclassification of preterm SGA status, and use of fetuses-at-risk denominators in regression models.

RESULTS

Although prevalence of SGA birth decreased over time, relative educational inequalities (PRs) persisted for preterm and term cases. PPDs decreased slightly, but more for term than preterm SGA birth. Sensitivity analyses indicated that PRs for education were stronger for preterm than term SGA birth. PPDs were larger for term SGA birth in the first period, but greater for preterm SGA birth in the last period.

CONCLUSIONS

Relative educational inequalities in SGA birth persisted over time. The difference in prevalence between the least and most educated mothers is currently greater for preterm than for term SGA birth.

Maternal pre-eclampsia is associated with childhood epilepsy in South Carolina children insured by Medicaid

OBJECTIVE

We examined the association between maternal pre-eclampsia/eclampsia (PE) and childhood epilepsy.

METHODS

We conducted a retrospective cohort study using linked maternal-child billing data for Medicaid births in South Carolina from 1996 through 2002, with follow-up billing data for children through December 2008. Women with PE (exposed) and children with epilepsy (outcome) were identified using ICD-9 codes. Non-singleton births, children with documented conditions known to cause abnormal brain development, and children who neither remained in Medicaid until age 6 nor were diagnosed with epilepsy were excluded.

RESULTS

Of 95,450 mother-child pairs in the final cohort, 5460 mothers were diagnosed with PE (5.7%) and 1106 children had the outcome of epilepsy (1.2%). After controlling for potential confounders, PE was significantly associated with risk of epilepsy (OR=1.46, 95% CI=1.17-1.82). The increased risk of epilepsy was observed only among full-term infants, and for this subgroup, late PE (first diagnosed after 37 weeks of gestation) was significantly associated with epilepsy (OR=1.61, 95% CI=1.21-2.16). The association between PE and epilepsy was particularly strong for children with focal epilepsy.

CONCLUSION

Pre-eclampsia is associated with childhood epilepsy. Additional research is needed to identify potential mechanisms for the association.