Why is there a modifying effect of gestational age on risk factors for cerebral palsy?

The aetiology of preterm birth and risks of cerebral palsy and cognitive impairment: A systematic review and meta-analysis

AIM

The associations between the aetiology of preterm birth and later neurodevelopmental outcomes are unclear. A systematic review and meta-analysis examined the existing evidence.

METHODS

The PubMed and Embase databases were searched for papers published in English from inception to 16 December 2020. We included original papers on the causes of preterm birth and the risks of cerebral palsy (CP) and suboptimal cognitive development. Two reviewers independently evaluated the studies and extracted the data.

RESULTS

The literature search yielded 5472 papers and 13 were selected. The aetiology of preterm birth was classified under spontaneous or medically indicated delivery. A meta-analysis was performed, comprising 104 902 preterm infants from 11 papers on CP. Preterm infants born after a medically indicated delivery had a lower CP risk than infants born after spontaneous delivery, with a pooled odds ratio of 0.59 (95% confidence interval 0.40-0.86). This result was robust in the subgroup and sensitivity analyses. Cognitive development was reported in three papers, which suggested that worse outcomes were associated with medically indicated deliveries.

CONCLUSION

The aetiology of preterm delivery may contribute to the risk of CP and cognitive delay. Further research is needed, using individual-level meta-analyses to adjust for possible confounders, notably gestational age.

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.

A Retrospective Cohort Study on Mortality and Neurodevelopmental Outcomes of Preterm Very Low Birth Weight Infants Born to Mothers with Hypertensive Disorders of Pregnancy

OBJECTIVE

We examined the effects of maternal hypertensive disorders of pregnancy (HDP) on the mortality and neurodevelopmental outcomes in preterm very low birth weight (VLBW) infants (BW ≤1,500 g) based on their intrauterine growth status and gestational age (GA).

STUDY DESIGN

We included singleton VLBW infants born at <32 weeks' gestation registered in the Neonatal Research Network Japan database. The composite outcomes including death, cerebral palsy (CP), and developmental delay (DD) at 3 years of age were retrospectively compared among three groups: appropriate for GA (AGA) infants of mothers with and without HDP (H-AGA and N-AGA) and small for GA (SGA) infants of mothers with HDP (H-SGA). The adjusted odds ratios (AOR) and 95% confidence intervals (CI) stratified by the groups of every two gestational weeks were calculated after adjusting for the center, year of birth, sex, maternal age, maternal diabetes, antenatal steroid use, clinical chorioamnionitis, premature rupture of membranes, non-life-threatening congenital anomalies, and GA.

RESULTS

Of 19,323 eligible infants, outcomes were evaluated in 10,192 infants: 683 were H-AGA, 1,719 were H-SGA, and 7,790 were N-AGA. Between H-AGA and N-AGA, no significant difference was observed in the risk for death, CP, or DD in any GA groups. H-AGA had a lower risk for death, CP, or DD than H-SGA in the 24 to 25 weeks group (AOR: 0.434, 95% CI: 0.202-0.930). The odds for death, CP, or DD of H-SGA against N-AGA were found to be higher in the 24 to 25 weeks (AOR: 2.558, 95% CI: 1.558-3.272) and 26 to 27 weeks (AOR: 1.898, 95% CI: 1.427-2.526) groups, but lower in the 30 to 31 weeks group (AOR: 0.518, 95% CI: 0.335-0.800).

CONCLUSION

There was a lack of follow-up data; however, the outcomes of liveborn preterm VLBW infants of mothers with HDP depended on their intrauterine growth status and GA at birth.

KEY POINTS

· The effects of HDP on preterm low birth weight infants need to be further examined.. · The outcomes were not different between AGA infants with and without maternal HDP.. · The outcomes of SGA infants with maternal HDP were dependent on their GA..

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.

Prevalence and characteristics of children with cerebral palsy according to socioeconomic status of areas of residence in a French department

Aim

To study the association between the socioeconomic environment of area of residence and prevalence and characteristics of children with cerebral palsy (CP).

Method

Data on 8-year-old children with CP born in 2000–2011 (n = 252) were extracted from a regional population-based register in France. The European Deprivation Index (EDI), available at census block level, characterised socioeconomic deprivation in the child’s area of residence at age of registration. The prevalence of CP was estimated in each group of census units defined by EDI distribution tertiles in the general population. The association between deprivation level and CP severity was assessed according to term/preterm status.

Results

CP prevalence differed between deprivation risk groups showing a J-shaped form with the prevalence in the most deprived tertile (T3) being the highest but not significantly different of the prevalence in the least deprived one (T1). However, the prevalence in the medium deprivation tertile (T2) was significantly lower than that in the most deprived one with a prevalence risk ratio (PRR) of: PRRT2/T3 = 0.63 95% CI [0.44–0.89]). Prevalences of CP with associated intellectual disability (ID) and CP with inability to walk were significantly higher in the most deprived tertile compared to the least deprived one (respectively PRRT3/T1 = 1.86 95% CI [1.19–2.92] and PRRT3/T1 = 1.90 95% CI [1.07–3.37]). Compared to children living in the least deprived areas, children with CP born preterm living in the most deprived areas had more severe forms of motor impairment, such as an inability to walk or a combination of an inability to walk and moderate to severe impairment of bimanual function. They also had more associated intellectual disability. No associations were observed among term-born children.

Interpretation

A significant association between area deprivation group and CP severity was observed among preterm children but not among term-born children.

The Antenatal and Postnatal Consequences of Antenatal Exposure to Prolonged Low Dose Indomethacin

Despite its many clinical applications, indomethacin is seldom used in pregnancy, principally because of concerns regarding the potential for constriction of the arterial duct. The aim of this study was to document adverse antenatal effects and postnatal outcomes after in utero exposure to low-dose indomethacin. We studied a retrospective cohort of pregnancies between 2005 and 2016 at the John Radcliffe Hospital, Oxford, UK, in which mothers at extremely high risk of preterm birth were treated as prophylaxis with indomethacin 25 mg, 12 hourly, before 29 weeks. Antenatal effects on the arterial duct and postnatal outcomes were analysed. Overall, 198 fetuses had in utero follow-up, and 13 (6.6%) had ductal constriction, all within 9 days of starting treatment. No ductal constriction was seen in pregnancies when therapy was started before 20 weeks, and all effects were reversed after cessation of therapy. An analysis of postnatal complications was possible in 181 neonates. There were eight (4.4%) neonatal deaths, all but one associated with extreme preterm birth. Seven (5%) patent ductus arteriosus cases occurred in the 140 neonates delivered after 28 weeks who were alive at discharge. Postnatal complications were not more common in neonates in whom antenatal ductal constriction had been demonstrated. In conclusion, fetuses exposed to prolonged low dose indomethacin have a low incidence of in utero complications; these complications can be diagnosed with ultrasound and are reversible. Adverse postnatal events are related to gestation at birth and do not appear more common.

Maternal Infection During Pregnancy and Risk of Cerebral Palsy in Children: A Systematic Review and Meta-analysis

BACKGROUND AND AIM

The association between maternal infection during pregnancy and the risk of cerebral palsy has been previously reported. However, their results were relatively inconsistent. This systematic review and meta-analysis were carried out to investigate the association between maternal infection during pregnancy and the risk of cerebral palsy in children.

METHODS

PubMed, Scopus, and Web of Sciences databases were searched from inception to October 28, 2019. Heterogeneity was assessed using the I² value. In case of substantial heterogeneity (I² > 50%), a random effects model was applied, otherwise, a fixed effects model was used. The pooled associations were expressed as relative risks (RRs) and 95% confidence intervals (CIs). Publication bias and quality of studies included in the systematic review were checked using the Egger's regression test and Newcastle-Ottawa Scale (NOS), respectively.

RESULTS

Thirty-seven studies were included in the systematic review. Among them, 21 studies were eligible for the meta-analysis. The pooled RR of cerebral palsy risk was 2.50 (95% CI 1.94, 3.21; I² = 88.7%, P < .001) among children born to mothers who had any infection during pregnancy. The risk was increased to 2.85 (95% CI 1.96, 4.15; I² = 75.9%, P < .001) when the mother was diagnosed with chorioamnionitis. Publication bias tests suggested no evidence of potential publication bias and 76% of the studies included in the meta-analysis were of high quality (NOS ≥ 6).

CONCLUSION

This systematic review and meta-analysis provides evidence that maternal infection during pregnancy may be associated with an increased risk of cerebral palsy in children.

The influence of neonatal infections on the development of cerebral palsy

One of the most significant biological factors predisposing to cerebral palsy (CP) are infections. The paper aims to analyze neonatal infections’ influence in the risk of CP development with consideration of all significant risk factors including single, twin, full-term and pre-term pregnancies.

278 children with CP attending the chosen school-educational centers in Poland were included in the questionnaire. The control group included data obtained from the medical documentation of 435 children born in Limanowa County Hospital, Poland. Socio-economic factors, factors connected with pregnancy, and the coexisting disorders and diseases in children were taken into consideration. Constructed models of logistic regression were applied in the statistical analysis.

Neonatal infections increase the risk of CP development in all children (odds ratio (OR) 5.1, 95% confidence interval (CI) 2.6–9.8), children from single pregnancies (OR 5.8, 95% CI: 3.0–11.29), full-term (OR 6.2, 95% CI: 3.2–12.3), and single full-term pregnancies (OR 6.0, 95% CI: 3.0–12.0). The influence of neonatal infections in the risk of CP development in children from pre-term and single premature pregnancies was not indicated.

Neonatal infections are an independent risk factor for CP development in newborns from full-term pregnancy (>37 weeks of pregnancy). The patho-mechanism of CP is different in children from full-term and premature pregnancy and results from interrelating factors are discussed in this paper.

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.

Epidural analgesia, intrapartum hyperthermia, and neonatal brain injury: a systematic review and meta-analysis

BACKGROUND

Epidural analgesia is associated with intrapartum hyperthermia, and chorioamnionitis is associated with neonatal brain injury. However, it is not known if epidural hyperthermia is associated with neonatal brain injury. This systematic review and meta-analysis investigated three questions: (1) does epidural analgesia cause intrapartum hyperthermia, (2) is intrapartum hyperthermia associated with neonatal brain injury, and (3) is epidural-induced hyperthermia associated with neonatal brain injury?

METHODS

PubMed, ISI Web of Knowledge, The Cochrane Library, and Embase were searched from inception to January 2020 using Medical Subject Headings (MeSH) terms relating to epidural analgesia, hyperthermia, labour, and neonatal brain injury. Studies were reviewed independently for inclusion and quality by two authors (Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach). Two meta-analyses were performed using the Mantel-Haenszel fixed effect method to generate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Forty-one studies were included for Question 1 (646 296 participants), 36 for Question 2 (11 866 021 participants), and two studies for Question 3 (297 113 participants). When the mode of analgesia was randomised, epidural analgesia was associated with intrapartum hyperthermia (OR: 4.21; 95% CI: 3.48-5.09). There was an association between intrapartum hyperthermia and neonatal brain injury (OR: 2.79; 95% CI: 2.54-2.3.06). It was not possible to quantify the association between epidural-induced hyperthermia and neonatal brain injury.

CONCLUSIONS

Epidural analgesia is a cause of intrapartum hyperthermia, and intrapartum hyperthermia of any cause is associated with neonatal brain injury. Further work is required to establish if epidural-induced hyperthermia is a cause of neonatal brain injury.

Associations between antenatal and perinatal risk factors and cerebral palsy: a Swedish cohort study

OBJECTIVES

To investigate known and suggested risk factors associated with cerebral palsy in a Swedish birth cohort, stratified by gestational age.

SETTING

Information on all births between 1995 and 2014 in Skåne, the southernmost region in Sweden, was extracted from the national birth register.

PARTICIPANTS

The cohort comprised a total of 215 217 children. Information on confirmed cerebral palsy and subtype was collected from the national quality register for cerebral palsy (Cerebral Palsy Follow-up Surveillance Programme).

PRIMARY AND SECONDARY OUTCOME MEASURES

We calculated the prevalence of risk factors suggested to be associated with cerebral palsy and used logistic regression models to investigate the associations between potential risk factors and cerebral palsy. All analyses were stratified by gestational age; term (≥37 weeks), moderately or late preterm (32-36 weeks) and very preterm (<32 weeks).

RESULTS

In all, 381 (0.2 %) children were assigned a cerebral palsy diagnosis. Among term children, maternal preobesity/obesity, small for gestational age, malformations, induction, elective and emergency caesarian section, Apgar <7 at 5 min and admission to neonatal care were significantly associated with cerebral palsy (all p values<0.05). Among children born moderately or late preterm, small for gestational age, malformations, elective and emergency caesarian section and admission to neonatal care were all associated with cerebral palsy (all p values <0.05), whereas among children born very preterm no factors were significantly associated with the outcome (all p values>0.05).

CONCLUSION

Our results support and strengthen previous findings on factors associated with cerebral palsy. The complete lack of significant associations among children born very preterm probably depends on to the small number of children with cerebral palsy in this group.

Maternal hypertension and survival in singletons and twins born at 23-29 weeks: not just one answer…

BACKGROUND

To describe the association between maternal hypertension (chronic and gestational, MH) and mortality in very preterm singletons and twins, focusing on how estimates depend on gestational age (GA) and size at birth.

METHODS

We estimated relative risks of in-hospital death in 12,320 singletons (MH: 22.4%) and 4381 twins (MH: 10.6%) born at 23-29 weeks in the Italian Neonatal Network (89 hospitals, 2008-2016).

RESULTS

Babies with MH had higher GA and were more frequently small-for-gestational age (SGA), especially singletons. In crude analyses, MH was associated with lower mortality in singletons. In multivariable analyses, the effects of GA and size differed between twins and singletons with and without MH. The best-fitting models included continuous birth weight (rather than SGA) and were stratified by GA. In these models, MH was associated with lower mortality in singletons-but not twins-born after week 25.

CONCLUSIONS

In this cohort of very preterm infants, the association between MH and mortality differed between singletons and twins and across strata of GA at birth. These estimates cannot be interpreted causally, but suggest that, from a descriptive/predictive standpoint, singletons with MH born after week 25 have lower mortality than singletons born to women without MH.

Causal inference in studies of preterm babies: a simulation study

OBJECTIVE

Using a simple simulation, we illustrate why associations estimated from studies restricted to preterm births cannot be interpreted causally.

DESIGN, SETTING AND POPULATION

Data simulation involving a hypothetical cohort of fetuses who may be healthy or have one or more of four pathological factors (termed A through D, increasing in severity) with known effects on gestational length and risk of mortality. We focus on babies born at ≤32 weeks of gestation.

METHODS

We visually represent the simulated population and compare the association between A (which may represent pre-eclampsia) and neonatal death. We then repeat the exercise with D (standing in for chorioamnionitis) as the exposure of interest.

MAIN OUTCOME MEASURES

Odds ratios of neonatal death in the simulated data.

RESULTS

In most weeks, and for both A and D, the calculated odds ratios are substantially biased and underestimate the true risk of neonatal death associated with each pathology. For example, factor A has a true causal odds ratio of 1.50, yet it appears protective among births ≤32 weeks (estimated crude odds ratio 0.39; gestational age-adjusted odds ratio 0.71).

CONCLUSIONS

Among very preterm births, virtually all babies are born with pathologies that increase the risk of adverse outcomes. Hence, babies exposed to one factor (e.g. pre-eclampsia) are compared with babies who have a mix of other pathologies. Such selection bias affects studies carried out among very preterm births (e.g. where pre-eclampsia appears to reduce risk of adverse neonatal outcomes).

TWEETABLE ABSTRACT

Selection bias affects studies of preterm births, complicating interpretation.

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.

SGA as a Risk Factor for Cerebral Palsy in Moderate to Late Preterm Infants: a System Review and Meta-analysis

Small for gestational age (SGA) is an established risk factor for cerebral palsy (CP) in term infants. However, there is conflicting data on the association between SGA and CP in moderate to late preterm infants. The aim of the article was to explore the relationship between SGA and CP in the moderate to late preterm infants and its strength by meta-analysis. We performed a system search in OVID (EMBASE and MEDLINE) and WANFANG from inception to May 2016. The study-specific risk estimates were pooled using the random-effect model. A total of seven studies were included in the meta-analysis, consisting of three cohort and four case-control studies. A statistically significant association was found between SGA and CP in moderate to late premature infants (OR: 2.34; 95% CI: 1.43-3.82). The association were higher in the several subgroups: 34-36 week gestational age (OR: 3.47; 95% CI: 1.29-9.31), SGA < 2SDs (OR: 3.48; 95% CI: 1.86-6.49), and malformation included in CP (OR: 3.00; 95% CI: 1.71-5.26). In moderate to late premature infants, SGA is a convenient and reliable predictor for CP. More studies are needed to explore the underlying mechanisms between SGA and CP association.

Melatonin for women in pregnancy for neuroprotection of the fetus

BACKGROUND

Melatonin is an antioxidant with anti-inflammatory and anti-apoptotic effects. Animal studies have supported a fetal neuroprotective role for melatonin when administered maternally. It is important to assess whether melatonin, given to the mother, can reduce the risk of neurosensory disabilities (including cerebral palsy) and death, associated with fetal brain injury, for the preterm or term compromised fetus.

OBJECTIVES

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

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 January 2016).

SELECTION CRITERIA

We planned to include randomised controlled trials and quasi-randomised controlled trials comparing melatonin given to women in pregnancy (regardless of the route, timing, dose and duration of administration) for fetal neuroprotection with placebo, no treatment, or with an alternative agent aimed at providing fetal neuroprotection. We also planned to include comparisons of different regimens for administration of melatonin.

DATA COLLECTION AND ANALYSIS

Two review authors planned to independently assess trial eligibility, trial quality and extract the data.

MAIN RESULTS

We found no randomised trials for inclusion in this review. One study is ongoing.

AUTHORS' CONCLUSIONS

As we did not identify any randomised trials for inclusion in this review, we are unable to comment on implications for practice at this stage.Although evidence from animals studies has supported a fetal neuroprotective role for melatonin when administered to the mother during pregnancy, no trials assessing melatonin for fetal neuroprotection in pregnant women have been completed to date. However, there is currently one ongoing randomised controlled trial (with an estimated enrolment target of 60 pregnant women) which examines the dose of melatonin, administered to women at risk of imminent very preterm birth (less than 28 weeks' gestation) required to reduce brain damage in the white matter of the babies that were born very preterm.Further high-quality research is needed and research efforts should directed towards trials comparing melatonin with either no intervention (no treatment or placebo), or with alternative agents aimed at providing fetal neuroprotection (such as magnesium sulphate for the very preterm infant). Such trials should evaluate maternal and infant short- and longer-term outcomes (including neurosensory disabilities such as cerebral palsy), and consider the costs of care.

Implications of Using a Fetuses-at-Risk Approach When Fetuses Are Not at Risk

BACKGROUND

Gestational-age-specific rates of postnatal endpoints are sometimes estimated with denominators based on fetuses-at-risk (FAR), rather than live births. However, as infants can only be included in the numerator after they are born alive, interpretation of such rates is problematic.

METHODS

Using simple algebra it can be shown that, at each gestational week, FAR rates of postnatal endpoints are the product of the conventional risk of outcome among live births and the probability of live birth, which increases from near zero early in gestation to close to one in the final weeks. The consequences of such a pattern of live birth on FAR rates are further illustrated in hypothetical scenarios with known conditions.

RESULTS

FAR rates of postnatal endpoints will generally increase towards the end of pregnancy due to the rising probability of live birth, regardless of the 'true' effect of immaturity on risk. In the presence of an exposure that increases the probability of early birth, the same mechanism will cause FAR rates to be higher in the exposed group, even if the exposure has no effect.

CONCLUSIONS

Gestational-age-specific FAR rates of postnatal outcomes strongly depend on the probability of live birth. Thus, they reflect neither the causal effect of gestational length, nor that of a given exposure. Indeed, if an exposure shortens gestation, FAR rates will be higher in exposed infants even when the exposure has no impact on the outcome under study. These intrinsic limitations should be taken into account when applying FAR analyses to postnatal endpoints.

Association between unintentional injury during pregnancy and excess risk of preterm birth and its neonatal sequelae

The sequelae of preterm births may differ, depending on whether birth follows an acute event or a chronic condition. In a population-based cohort study of 2,711,645 Canadian hospital deliveries from 2003 to 2012, 3,059 women experienced unintentional injury during pregnancy. We assessed the impact of the acute event on pregnancy outcome and on neonatal complications, such as nontraumatic intracranial hemorrhage, respiratory distress syndrome, intubation, and death. We adjusted for maternal age, parity, pregnancy conditions, and (for neonates) gestational age in logistic regression analyses. Injury was significantly associated with fetal mortality and early preterm delivery. For preterm infants born to injured women during the hospitalization for injury versus those born to noninjured women, the adjusted odds ratios were 2.25 (95% confidence interval (CI): 1.23, 4.17) for neonatal death, 2.44 (95% CI: 1.76, 3.37) for respiratory distress, 2.20 (95% CI: 1.26, 3.84) for nontraumatic intracranial hemorrhage, and 2.17 (95% CI: 1.60, 2.96) for intubation, despite more favorable fetal growth in those born to noninjured women (adjusted birth-weight-for-gestational-age z score: 0.154 vs. 0.024, P = 0.041; small-for-gestational-age rate: 4.5% vs. 9.5%, P = 0.001). Our findings suggest that adaptation to the suboptimal intrauterine environment underlying chronic causes of preterm birth may protect preterm infants from adverse sequelae.

Disproportionate fetal growth and the risk for congenital cerebral palsy in singleton births

OBJECTIVE

To investigate the association between proportionality of fetal and placental growth measured at birth and the risk for congenital cerebral palsy (CP).

STUDY DESIGN

We identified all live-born singletons born in Denmark between 1995 and 2003 and followed them from 1 year of age until December 31st, 2008. Information on four indices of fetal growth: ponderal index, head circumference/ abdominal circumference ratio, cephalization index and birth weight/ placenta weight ratio was collected. Cox proportional hazards regression models were used to estimate adjusted hazard ratios (aHR) and 95% confidence intervals (CI). All measurements were evaluated as gestational age and sex specific z-scores and in z-score percentile groups, adjusted for potential confounders, and stratified on gestational age groups (<32, 32-36, 37-38, 39, 40, ≥ 41 weeks).

RESULTS

We identified 503,784 singleton births, of which 983 were confirmed cases of CP. Head/ abdominal circumference ratio (aHR:1.12; 95%CI:1.07-1.16) and cephalization index (aHR:1.14; 95%CI:1.11-1.16) were associated with the risk of CP irrespective of gestational age. Birth weight-placental weight ratio was also associated with CP in the entire cohort (aHR:0.90; 95%CI:0.83-0.97). Ponderal index had a u-shaped association with CP, where both children with low and high ponderal index were at higher risk of CP.

CONCLUSIONS

CP is associated with disproportions between birth weight, birth length, placental weight and head circumference suggesting pre and perinatal conditions contribute to fetal growth restriction in children with CP.

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.

Risk of cerebral palsy among the offspring of immigrants

BACKGROUND

Cerebral palsy (CP) has a multifactorial etiology, and placental vascular disease may be one major risk factor. The risk of placental vascular disease may be lower among some immigrant groups. We studied the association between immigrant status and the risk of CP.

METHODS

We conducted a population-based retrospective cohort study of all singleton and twin livebirths in Ontario between 2002-2008, and who survived ≥28 days after birth. Each child was assessed for CP up to age 4 years, based on either a single inpatient or ≥2 outpatient pediatric diagnoses of CP. Relative to non-immigrants (n = 566,668), the risk of CP was assessed for all immigrants (n = 177,390), and further evaluated by World region of origin. Cox proportional hazard ratios (aHR) were adjusted for maternal age, income, diabetes mellitus, obesity, tobacco use, Caesarean delivery, year of delivery, physician visits, twin pregnancy, preterm delivery, as well as small- and large-for-gestational age birthweight.

RESULTS

There were 1346 cases of CP, with a lower rate among immigrants (1.45 per 1000) than non-immigrants (1.92 per 1000) (aHR 0.77, 95% confidence interval [CI] 0.67 to 0.88). Mothers from East Asia and the Pacific (aHR 0.54, 95% CI 0.39 to 0.77) and the Caribbean (aHR 0.58, 95% CI 0.37 to 0.93) were at a significantly lower risk of having a child with CP. Whether further adjusting for preeclampsia, gestational hypertension, placental abruption or placental infraction, or upon using a competing risk analysis that further accounted for stillbirth and neonatal death, these results did not change.

CONCLUSIONS

Immigration and ethnicity appear to attenuate the risk of CP, and this effect is not fully explained by known risk factors.

Association of maternal hypertension and chorioamnionitis with preterm outcomes

OBJECTIVES

We compared the relative effect of hypertensive disorders of pregnancy and chorioamnionitis on adverse neonatal outcomes in very preterm neonates, and studied whether gestational age (GA) modulates these effects.

METHODS

A cohort of neonates 23 to 30 weeks' GA, born in 2008 to 2011 in 82 hospitals adhering to the Italian Neonatal Network, was analyzed. Infants born from mothers who had hypertensive disorders (N = 2096) were compared with those born after chorioamnionitis (N = 1510). Statistical analysis employed logistic models, adjusting for GA, hospital, and potential confounders.

RESULTS

Overall mortality was higher after hypertension than after chorioamnionitis (odds ratio [OR], 1.39; 95% confidence interval [CI], 1.08-1.80), but this relationship changed across GA weeks; the OR for hypertension was highest at low GA, whereas from 28 weeks' GA onward, mortality was higher for chorioamnionitis. For other outcomes, the relative risks were constant across GA; infants born after hypertension had an increased risk for bronchopulmonary dysplasia (OR, 2.20; 95% CI, 1.68-2.88) and severe retinopathy of prematurity (OR, 1.48; 95% CI, 1.02-2.15), whereas there was a lower risk for early-onset sepsis (OR, 0.25; 95% CI, 0.19-0.34), severe intraventricular hemorrhage (OR, 0.65; 95% CI, 0.48-0.88), periventricular leukomalacia (OR, 0.70; 95% CI, 0.48-1.01), and surgical necrotizing enterocolitis or gastrointestinal perforation (OR, 0.47; 95% CI, 0.31-0.72).

CONCLUSIONS

Mortality and other adverse outcomes in very preterm infants depend on antecedents of preterm birth. Hypertension and chorioamnionitis are associated with different patterns of outcomes; for mortality, the effect changes across GA weeks.

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.

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 systematic review of risk factors for cerebral palsy in children born at term in developed countries

AIM

The aim of this study was to conduct a systematic review in order to identify the risk factors for cerebral palsy (CP) in children born at term. The secondary aim was to ascertain if the potential for prevention of these risk factors has been adequately explored.

METHOD

A MEDLINE search up to 31 July 2011 was completed, following the Meta-Analysis of Observational Studies in Epidemiology guidelines. Publications were reviewed to identify those with both a primary aim of identifying risk factors for all children or term-born children with CP and a cohort or case-control study design. Studies were examined for potential chance or systematic bias. The range of point estimates of relative risk is reported.

RESULTS

From 21 articles meeting inclusion/exclusion criteria and at low risk of bias, data from 6297 children with CP and 3 804 791 children without CP were extracted. Ten risk factors for term-born infants were statistically significant in each study: placental abnormalities, major and minor birth defects, low birthweight, meconium aspiration, instrumental/emergency Caesarean delivery, birth asphyxia, neonatal seizures, respiratory distress syndrome, hypoglycaemia, and neonatal infections. Strategies for possible prevention currently exist for three of these.

INTERPRETATION

Ten consistent risk factors have been identified, some with potential for prevention. Efforts to prevent these risk factors to interrupt the pathway to CP should be extended.

Intra-partum fever and cerebral palsy in Khartoum, Sudan

Background

Cerebral palsy (CP) is a major cause of childhood disability. There are various maternal and neonatal predictors associated with the development of CP, and they are variable across different populations. This case–control study was designed to investigate maternal and neonatal predictors of CP at Khartoum pediatric neurology clinics. Data (maternal sociodemographic characteristics and neonatal expected predictors) were collected from mothers of children with CP and healthy controls using questionnaires.

Results

One hundred and eleven cases of CP and 222 controls were included. Spastic CP was the most common type (69.4%). In logistic regression, maternal age, parity, birth weight, and sex were not associated with CP. However, maternal fever (OR = 8.4, CI = 2.3–30.5; P = 0.001), previous neonatal death (OR = 5.4, CI = 1.8–16.2; P = 0.003), and poor sucking (OR = 30.5, CI = 10.0–93.1; P < 0.001) were predictors of CP.

Conclusions

Fever during labor is a significant risk factor for developing CP in children. Further efforts are required for labor management to prevent CP in this setting.

Perinatal and early postnatal factors underlying developmental delay and disabilities

A delay in meeting developmental milestones may be secondary to perinatal events, involving complicated interactions between mother and fetus during delivery. Maternal factors including weight, diet, and morbidities can affect neonatal adaptation and later development. Prematurity, low birth weight, and previous intrauterine insults as well as complications during delivery of a previously normal fetus increase the risk for perinatal stress. In this article, the literature on perinatal and early postnatal factors that underlie risks for developmental delay and disabilities is reviewed. Studies that concern neuroprotective therapies and prediction of long-term neurologic outcome by clinical examination, neuroimaging techniques, and electroencephalographic studies are reviewed as well.

Are maternal genitourinary infection and pre-eclampsia associated with ADHD in school-aged children?

OBJECTIVE

To investigate the hypothesis that maternal genitourinary infection (GU) infection is associated with increased risk of ADHD.

METHOD

The authors obtained linked Medicaid billing data for pregnant women and their children in South Carolina, with births from 1996 through 2002 and follow-up data through 2008. Maternal GU infections and pre-eclampsia were identified on the basis of diagnoses made during pregnancy, and cases of ADHD were identified on the basis of diagnoses made in the child's Medicaid file.

RESULTS

There were 84,721 children in the data set used for analyses. Maternal genitourinary infection was associated with significantly increased odds of ADHD (OR = 1.29, 95% CI = 1.23-1.35). Pre-eclampsia was also associated with increased risk (OR = 1.19, 95% CI = 1.07-1.32). Children whose mothers had both GU infection and pre-eclampsia were 53% more likely to have ADHD, compared to those with neither exposure. When we examined specific infection diagnoses, chlamydia/nongonococcal urethritis, trichomoniasis, urinary tract infection, and candidiasis were associated with increased risk of ADHD, whereas gonorrhea was not.

DISCUSSION

Maternal GU infection appeared to be associated with increased risk of ADHD, and based on the findings it was concluded that further research is needed to describe the mechanism(s) underlying the association.

On the pitfalls of adjusting for gestational age at birth

Preterm delivery is a powerful predictor of newborn morbidity and mortality. Such problems are due to not only immaturity but also the pathologic factors (such as infection) that cause early delivery. The understanding of these underlying pathologic factors is incomplete at best. To the extent that unmeasured pathologies triggering preterm delivery also directly harm the fetus, they will confound the association of early delivery with neonatal outcomes. This, in turn, complicates studies of newborn outcomes more generally. When investigators analyze the association of risk factors with neonatal outcomes, adjustment for gestational age as a mediating variable will lead to bias. In the language of directed acyclic graphs, gestational age is a collider. The theoretical basis for colliders has been well described, and gestational age has recently been acknowledged as a possible collider. However, the impact of this problem, as well as its implications for perinatal research, has not been fully appreciated. The authors discuss the evidence for confounding and present simulations to explore how much bias is produced by adjustments for gestational age when estimating direct effects. Under plausible conditions, frank reversal of exposure-outcome associations can occur. When the purpose is causal inference, there are few settings in which adjustment for gestational age can be justified.

Might rare factors account for most of the mortality of preterm babies?

BACKGROUND

Preterm delivery has a variety of causes, with each of these presumably carrying its own mortality risk. To the extent that they add to the risk of mortality, the various pathologic factors triggering preterm delivery will confound the causal contribution of gestational age to mortality, inflating the observed rates of gestational-age-specific mortality. We have previously estimated that about half of the mortality of US preterm singletons may be due to unmeasured pathologies that increase mortality risk and also cause preterm birth. In this paper, we examine the impact that rare factors may have, at least in theory, on preterm mortality.

METHODS

We constructed a simple model of gestational-age-specific mortality, in which we arbitrarily selected a function to represent the mortality due to immaturity alone ("baseline" risk). We then added "unmeasured" confounding factors that cause mortality and also cause preterm birth. This construct allowed us to calculate, in simple scenarios, the proportion of preterm mortality that could be caused by unmeasured confounding.

RESULTS

We found that rare pathologies with moderate-to-strong effects can substantially contribute to preterm mortality. The presence of such rare factors can also produce an intersection of gestational-age-specific mortality curves when stratifying by known risk factors.

CONCLUSIONS

It is possible that a few relatively rare factors may account for a large fraction of preterm mortality. The search for such factors should be a primary focus of future research on preterm delivery.

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

Pre-eclampsia is a leading cause of preterm birth, which is strongly associated with cerebral palsy (CP). However, there is controversy about whether pre-eclampsia is associated with increased risk of CP. We evaluated the association between pre-eclampsia and CP in 122,476 mother-child pairs insured by the South Carolina Medicaid programme, with births between 1996 and 2002. Prenatal billing records were linked to the children's Medicaid billing records after birth until December 2008. The odds of CP were modelled using logistic regression with generalised estimating equations. There were 337 children (0.28%) diagnosed with CP by at least two different health care providers, and 4226 (3.5%) women were diagnosed with pre-eclampsia at least twice during pregnancy. Children whose mothers had pre-eclampsia were almost twice as likely to have CP compared with children of mothers without pre-eclampsia [odds ratio (OR)=1.94, 95% confidence interval (CI) 1.25, 2.97]. The association was only significant for pre-eclampsia diagnosed prior to 37 weeks' gestation. Full term (gestational age ≥ 37 weeks) infants whose mothers were diagnosed with pre-eclampsia prior to 37 weeks had increased odds of CP compared with full term children whose mothers did not have pre-eclampsia (OR=3.41, 95% CI 1.40, 8.31). Preterm infants whose mothers had pre-eclampsia were at significantly increased risk of CP compared with full term infants whose mothers did not have pre-eclampsia (OR=5.88, 95% CI 3.40, 10.17). The greatest risk for CP was in preterm infants whose mothers did not have pre-eclampsia (OR=8.12, 95% CI 6.49, 10.17 compared with full term infants without exposure to pre-eclampsia). We conclude that pre-eclampsia with onset before 37 weeks' gestation is a significant risk factor for CP. Some of the association is probably attributable to high risk of preterm birth because of early pre-eclampsia, while a 'direct' effect of pre-eclampsia on fetal brain development also seems likely.

Predictability of cerebral palsy in a high-risk NICU population

AIM

This study aims to create a predictive model for the assessment of the individual risk of developing cerebral palsy in a large cohort of selected high-risk infants.

PATIENTS AND METHODS

1099 NICU-admitted high-risk infants were assessed up to the corrected age of at least 12 months. CP was categorized relative to subtype, distribution and severity. Several perinatal characteristics (gender, gestational age, multiple gestation, small for gestational age, perinatal asphyxia and duration of mechanical ventilation), besides neonatal cerebral ultrasound data were used in the logistic regression model for the risk of CP.

RESULTS

Perinatal asphyxia, mechanical ventilation>7 days, white matter disease except for transient echodensities<7 days, intraventricular haemorrhage grades III and IV, cerebral infarction and deep grey matter lesions were recognized as independent predictors for the development of CP. 95% of all children with CP were correctly identified at or above the cut-off value of 4.5% probability of CP development. Higher gestational age, perinatal asphyxia and deep grey matter lesion are independent predictors for non-spastic versus spastic CP (OR=1.1, 3.6, and 7.5, respectively). Independent risk factors for prediction of unilateral versus bilateral spastic CP are higher gestational age, cerebral infarction and parenchymal haemorrhagic infarction (OR=1.2, 31, and 17.6, respectively). Perinatal asphyxia is the only significant variable retained for the prediction of severe CP versus mild or moderate CP.

CONCLUSION

The presented model based on perinatal characteristics and neonatal US-detected brain injuries is a useful tool in identifying specific infants at risk for developing CP.

Bronchopulmonary dysplasia and brain white matter damage in the preterm infant: a complex relationship

We analysed the relationship between bronchopulmonary dysplasia (BPD) and brain white matter damage (WMD) in very preterm infants, adjusting for common risk factors and confounders. We studied a cohort of infants <32 weeks gestational age (GA) and <1500 g, admitted to 12 hospitals in Northern Italy in 1999-2002. The association between BPD and WMD was estimated by generalised estimating equations and conditional logistic models, adjusting for centre, GA, propensity score for prolonged ventilation and other potential confounders. Directed acyclic graphs (DAG) were used to depict the underlying causal structure and guide analysis. Of the 1209 infants reaching 36 weeks, 192 (15.8%) developed BPD (supplemental oxygen at 36 weeks) and 88 (7.3%) ultrasound-defined WMD (cystic periventricular leukomalacia). In crude analysis, BPD was a strong risk factor for WMD [odds ratio (OR) = 5.9]. With successive adjustments, the OR progressively decreased to 3.88 when adjusting for GA, to 2.72 adding perinatal risk factors, and further down to 2.16 [95% confidence interval 1.1, 3.9] when ventilation was also adjusted for. Postnatal factors did not change the OR. Significant risk factors for WMD, in addition to BPD, were a low GA, a lower Apgar score, a higher illness severity score, ventilation and early-onset sepsis, while antenatal steroids, being small for GA, and surfactant were associated with a reduced risk. In conclusion, our data suggest that BPD is associated with an increased risk of WMD; most of the effect is due to shared risk factors and causal pathways. DAGs helped clarify the complex confounding of this scenario.

Health of children born to mothers who had preeclampsia: a population-based cohort study

OBJECTIVE

We assessed whether preeclampsia correlates with the long-term postnatal health of the offspring.

STUDY DESIGN

We conducted a population-based cohort study of 1,618,481 singletons born in Denmark (1978-2004) with up to 27 years of follow-up. We used Cox regression to estimate the associations between preeclampsia and long-term health outcomes of the offspring.

RESULTS

Children born at term exposed to preeclampsia had an increased risk of a variety of diseases, such as endocrine, nutritional, and metabolic diseases (incidence rate ratio, 1.6; 95% confidence interval, 1.5-1.7), and diseases of the blood and blood-forming organs (incidence rate ratio, 1.5; 95% confidence interval, 1.3-1.8). Children born preterm exposed to preeclampsia had a similar pattern of hospitalizations compared with the children born preterm unexposed to preeclampsia, although they had a decreased risk of cerebral palsy (incidence rate ratio, 0.7; 95% confidence interval, 0.6-0.9).

CONCLUSION

Preeclampsia was associated with an increased risk of being hospitalized for a number of diseases, especially in the children born at term.

Trends in the rates of cerebral palsy associated with neonatal intensive care of preterm children

Progressive changes in perinatal and neonatal intensive care of preterm infants since the late 1960s have led to an increase in survival and had an effect on the rates of neonatal morbidity, including brain injury, chronic lung disease, and sepsis. These have influenced the rates of neurodevelopmental impairment, including cerebral palsy. There was initially an increase in neonatal morbidity and rates of cerebral palsy associated with the increased survival of extremely low birth weight and low gestation infants. However, since the late 1990s and especially since the year 2000, the rates of neonatal morbidity have decreased with evidence of a decrease in the rates of cerebral palsy. Efforts to further decrease neonatal morbidity should continue to improve the outcomes of preterm children.

Preeclampsia and risk for epilepsy in offspring

OBJECTIVE

Eclampsia has been found to be a strong risk factor for epilepsy in the offspring, but it is unclear whether the risk also applies to the preceding condition, preeclampsia.

METHODS

We conducted a population-based cohort study of 1537860 singletons born in Denmark (1978-2004). Information on preeclampsia (mild, severe, and unspecified), eclampsia, and epilepsy was obtained from the Danish National Hospital Register. Information on gestational age, birth weight, and Apgar score was obtained from the Danish Medical Birth Registry. We used Cox proportional hazard models to estimate the incidence rate ratio of epilepsy for children who were exposed to preeclampsia or eclampsia in prenatal life.

RESULTS

We identified 45288 (2.9%) children who were exposed to preeclampsia (34823 to mild, 7043 to severe, and 3422 to unspecified preeclampsia) and 654 (0.04%) to eclampsia during their prenatal life. We identified 20260 people who received a diagnosis of epilepsy during up to 27 years of follow-up in the entire cohort. Prenatal exposure to preeclampsia was associated with an increased risk for epilepsy among children with a gestational age at birth of at least 37 weeks. For mild preeclampsia, the incidence rate ratios were 1.16 among children born at term and 1.68 for children born postterm; for severe preeclampsia, the incidence rate ratios were 1.41 among children born at term and 2.57 among children born postterm. No associations between preeclampsia and epilepsy were found among children who were born preterm. Eclampsia was associated with epilepsy with an incidence rate ratio of 1.29 for children born at term and 5.03 for children born postterm.

CONCLUSIONS

Prenatal exposure to both preeclampsia and eclampsia was associated with an increased risk of epilepsy in children born after 37 weeks of gestation.

The relationship between intrapartum maternal fever and neonatal acidosis as risk factors for neonatal encephalopathy

OBJECTIVES

This study was undertaken to investigate the relationship among maternal intrapartum fever, neonatal acidosis, and the risk of neonatal encephalopathy.

STUDY DESIGN

Cohort study of pregnancies at term. Logistic regression was used to estimate the effect of maternal fever and acidosis on the risk of neonatal encephalopathy. The potential interaction between maternal fever and acidosis was included in the models.

RESULTS

Of 8299 women, 25 neonates (0.3%) had encephalopathy develop. These were more often born acidotic (adjusted odds ratio 11.5; 95% CI, 5.0-26.5) or after a maternal intrapartum fever (adjusted odds ratio 8.1; 95% CI, 3.5-18.6). Where both risk factors coexisted, the risk was 12.5% (adjusted odds ratio 93.9; 95% CI, 28.7-307.2). Although this effect is multiplicative, there was no evidence of statistical interaction (P = .93); the effect of maternal fever on the risk of encephalopathy was similar in infants with (adjusted odds ratio 8.7; 95% CI, 2.4-31.7) and without acidosis (adjusted odds ratio 7.4; 95% CI, 2.4-21.9).

CONCLUSION

The combination of a maternal fever with cord acidosis greatly increases the risk of neonatal encephalopathy, but there is evidence against interaction between them, suggesting that they represent 2 separate causal pathways.

Agreement between maternal report and antenatal records for a range of pre and peri-natal factors: the influence of maternal and child characteristics

BACKGROUND

Events during pregnancy and labour may influence the future health and well-being of offspring. Many studies rely on maternal reports of pre and peri-natal factors. Both maternal and child characteristics may potentially influence the reliability and accuracy of maternal recall. However, this has not been previously examined.

AIMS

To examine agreement between information from maternally reported questionnaires and medical records for a range of pre and peri-natal factors. To examine whether maternal and child characteristics influence the level of agreement with medical records.

METHODS

A survey of women who had school aged children born following in vitro fertilization (IVF) was carried out. Mothers completed a postal questionnaire booklet which included the Lewis and Murray scale which asks about antenatal and obstetric complications and the Strengths and Difficulties Questionnaire which assesses child behaviour problems. Antenatal case notes were also reviewed. Multi-centre ethical approval was obtained. Complete data were available for 126 women.

RESULTS

The agreement between maternal report and medical records was very good for the majority of outcomes examined (infant birth weight, infant admission to special care baby unit, method of delivery, smoking during pregnancy, high blood pressure/oedema during pregnancy). Exceptions were length of labour and alcohol use during pregnancy. However, alcohol use during pregnancy was not routinely recorded in medical records. Maternal characteristics did not substantially influence level of agreement for the majority of outcomes examined. Exceptions were that agreement for length of labour was better in women with more educational qualifications and that agreement for pre-natal smoking was worse in women from higher socio-occupational groups. There was little evidence that child behaviour problems influenced the level of agreement between maternal recall and medical records.

CONCLUSIONS

For the majority of pre and peri-natal events examined, mothers can provide accurate reports in comparison to information from medical records.

Incidence and risk factors for cerebral palsy in infants with perinatal problems: a 15-year review

OBJECTIVE

Cerebral palsy (CP) is associated with prenatal, perinatal and postnatal factors. This is a retrospective case-control study aiming to determine the frequency of CP and examine risk factors for CP among infants cared for in the Neonatal Intensive Care Unit (NICU) covering Northwest Greece.

DESIGN AND PATIENTS

All neonates who were admitted to the NICU during the period 1989-2003 inclusive, and subsequently developed CP, were enrolled in the study, with matched controls. The incidence of CP was evaluated according to gestational age (GA): GA<34 weeks (group A) and GA>34 (group B), and study period: 1989-1996 (period I) and 1997-2003 (period II, during which intrauterine transfer and prenatal steroids were used).

RESULTS

CP was diagnosed in 78 children, 55 in group A and 23 in group B. The incidence of CP increased significantly with decreasing GA. Survival without CP increased significantly in children of GA<34 weeks during period II. The main factors associated with CP, identified by multivariate analysis, were (odds ratios, confidence interval), for group A: being small for gestational age (SGA) (2.5, 1.2-4.5) and patent ductus arteriosus (PDA) (3.4, 1.3-9.2) in period I, periventricular leucomalacia (PVL) (27, 4.8-209), prolonged rupture of membranes (PROM) (5.6, 1.8-18) and duration of mechanical ventilation (1.1, 1.05-1.2) in period II, and for group B: SGA (3.6, 1.3-9.9), neonatal transfer (3.06, 1.2-7.6), duration of mechanical ventilation (1.1, 1.06-1.25) and sepsis-meningitis (4.3, 1.2-16).

CONCLUSION

Improvement in survival without CP was observed in infants of GA<34 weeks during the later period of the study, and risk factors for CP in preterm infants depended on the study period. PVL, PROM and PDA were the most powerful independent predictors of CP in children of GA<34 weeks and SGA, neonatal transfer and sepsis/meningitis in children of GA>34 weeks.

Cerebral Palsy and the Application of the International Criteria for Acute Intrapartum Hypoxia

OBJECTIVE

To apply objective criteria for the identification of acute intrapartum hypoxia in a cohort of cerebral palsy cases and to identify other cerebral palsy-related pathologies.

METHODS

A cohort of all 235 neonates with cerebral palsy from a single Australian tertiary care center born between 1986 and 2003. Cases were identified from the South Australian Cerebral Palsy Register. Maternal and pediatric case notes were audited with application of the 2003 American College of Obstetricians and Gynecologists/American Academy of Pediatrics criteria to identify acute intrapartum hypoxia.

RESULTS

Data were available for analysis in 213 cases (91%). Major antenatal or pediatric cerebral palsy-related pathologies were identified in 98.1% of all these cases. An isolated acute intrapartum hypoxic event was defined as likely in only 2 of the 46 neonates born at term and none born preterm. Neonatal nucleated red blood cell counts were often high in neonates born preterm and following antenatal pathologies.

CONCLUSION

Cerebral palsy was seldom preceded by acute intrapartum hypoxia but antenatal cerebral palsy-related pathologies are often detectable. The objective American College of Obstetricians and Gynecologists/American Academy of Pediatrics criteria are useful to audit cerebral palsy causation and exclude primary intrapartum hypoxia.

LEVEL OF EVIDENCE

II-3.

Epidemiology of cerebral palsy

The term cerebral palsy refers to a range of clinical symptoms, with related service requirements, resulting from lesions or abnormalities in the brain arising early in life. It is not a diagnosis; aetiology and pathology are variable. This article discusses the definition and differential classification of cerebral palsy, describes trends in its frequency over time stratified by associated variables, and briefly reviews the most recent findings concerning its aetiology.