Lawrence Impey

The similarities between normal readers and developmental and acquired dyslexics

Abstract Recently several people have suggested strong similarities between the symptoms of acquired and developmental dyslexia. It is an interesting suggestion because it offers us a new way of looking at differences among dyslexic children (always a thorny problem) and also a possible explanation for these childrens difficulties. However, the symptoms in question could only be used as a basis for such an explanation if they really were distinctive, that is, did not crop up in normal children at the same reading level. We take two attempts to connect acquired with developmental dyslexia, each involving an adolescent girl who read roughly at the level of a 10-year-old child. One of these two girls (Temple & Marshall, 1983) read in a rather similar way to that of a typical phonological dyslexic. The other (Coltheart et al. 1983) resembled a typical surface dyslexic. Neither study included any comparison with normal children, and so one cannot be certain that there was anything unusual about either girls reading patterns. We gave the tests used in the two reports just mentioned to 16 normal readers, all reading at the 10-year-level, and we found evidence for all the symptoms described in those reports in normal children as well. The symptoms were not abnormal and cannot be used to explain the two dyslexic childrens difficulties. We also found strong and systematic individual differences in our normal group along a “phonological to surface” continuum. So our study does two things. One is show that the reading patterns reported by Temple and Marshall and of Coltheart et al. do not provide an explanation of the causes of these childrens reading difficulties. The other is to provide a new way of looking at qualitative differences among normal readers.

Fever in labour and neonatal encephalopathy: a prospective cohort study

Objective To determine whether the reported association of maternal fever with neonatal encephalopathy is independent of other associated intrapartum risk factors.

The relationship between umbilical cord arterial pH and serious adverse neonatal outcome: analysis of 51 519 consecutive validated samples

Please cite this paper as: Yeh P, Emary K, Impey L. The relationship between umbilical cord arterial pH and serious adverse neonatal outcome: analysis of 51 519 consecutive validated samples. BJOG 2012;119:824–831.

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.

Admission cardiotocography: a randomised controlled trial

BACKGROUND Admission cardiotocography is widely used to identify pregnancies that might benefit from continuous electronic fetal monitoring in labour. We aimed to compare the effect on neonatal outcome of admission cardiotocography versus intermittent auscultation of the fetal heart rate. METHODS 8580 women admitted to the delivery ward of a Dublin teaching hospital who were at low risk of fetal distress in labour were randomly assigned admission cardiotocography (20 min) or the units usual care (intermittent auscultation only, with continuous cardiotocography only if clinically indicated). The primary outcome was moderate to severe neonatal morbidity, or perinatal mortality in the absence of a major congenital malformation. Analyses were by intention to treat. FINDINGS 44 (1.0%) women assigned admission cardiotocography did not undergo the procedure; 15 (0.4%) assigned usual care had admission cardiotocography. The primary endpoint occurred in 56 (1.3%) of 4298 women assigned admission cardiotocography and 55 (1.3%) of 4282 in the usual-care group (relative risk 1.01; 95% CI 0.70-1.47). Other indices of neonatal morbidity also showed no differences. Despite an increase in use of continuous cardiotocography (1.39; 1.33-1.45) and fetal blood sampling (1.30; 1.14-1.47) with admission cardiotocography, there were no significant differences in the rates of caesarean delivery (1.13; 0.92-1.40), instrumental delivery (1.03; 0.92-1.16), or episiotomy (1.06; 0.99-1.13). INTERPRETATION Routine use of cardiotocography for 20 min on admission to the delivery ward does not improve neonatal outcome. No significant increase in operative delivery was apparent, probably because of liberal use of fetal blood sampling.

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

Objective: To investigate risk factors for cerebral palsy in relation to gestational age. Design: Three case-control studies within a geographically defined cohort. Setting: The former Oxfordshire Health Authority. Participants: A total of 235 singleton children with cerebral palsy not of postnatal origin, born between 1984 and 1993, identified from the Oxford Register of Early Childhood Impairment; 646 controls matched for gestation in three bands: ⩽32 weeks; 33–36 weeks; ⩾37 weeks. Results: Markers of intrapartum hypoxia and infection were associated with an increased risk of cerebral palsy in term and preterm infants. The odds ratio (OR) for hypoxia was 12.2 (95% confidence interval 1.2 to 119) at ⩽32 weeks and 146 (7.4 to 3651) at ⩾37 weeks. Corresponding ORs for neonatal sepsis were 3.1 (1.8 to 5.4) and 10.6 (2.1 to 51.9). In contrast, pre-eclampsia carried an increased risk of cerebral palsy at ⩾37 weeks (OR 5.1 (2.2 to 12.0)) but a decreased risk at ⩽32 weeks (OR 0.4 (0.2 to 1.0)). However, all infants ⩽32 weeks with maternal pre-eclampsia were delivered electively, and their risk of cerebral palsy was no lower than that of other electively delivered ⩽32 week infants (OR 0.9 (0.3 to 2.7)). Nearly 60% of ⩽32 week controls were delivered after spontaneous preterm labour, itself an abnormal event. Conclusion: Inflammatory processes, including pre-eclampsia, are important in the aetiology of cerebral palsy. The apparent reduced risk of cerebral palsy associated with pre-eclampsia in very preterm infants is driven by the characteristics of the gestation matched control group. Use of the term “protective” in this context should be abandoned.

The complications of external cephalic version : results from 805 consecutive attempts

Most breech babies at term are now delivered by caesarean section. Although external cephalic version reduces the number of term breech presentations, its uptake has not been as wide as is recommended by professional bodies. This may be because of fears over safety. Pooled safety data do exist, largely from case series. However, the possibility of reporting and publication biases in such studies maybe preventing both women and obstetricians from being adequately reassured. In this series of 805 consecutive version attempts, we report an extremely low complication rate and 0.5% risk of emergency caesarean section after the procedure.

Examination of the association between male gender and preterm delivery

OBJECTIVE To examine possible reasons why a male fetus constitutes a risk factor for preterm delivery. STUDY DESIGN Retrospective study of deliveries from hospital database in a UK teaching hospital. The population comprised all deliveries >23 weeks over an 11-year period, excluding multiples, terminations and pregnancies with major abnormalities including indeterminate gender. Obstetric variables and outcomes were initially compared in male and female babies for preterm births in different gestation bands, extreme (<28 weeks), severe (29-32 weeks) and moderate (33-36 weeks). For each, the odds ratios with 95% confidence intervals for preterm delivery were calculated. Then, using binary logistic regression with adjusted odds ratios with 95% confidence intervals, putative causal pathways that might explain the male excess were tested. RESULTS 75,725 deliveries occurred, of which 4003 (5.3%) were preterm. Males delivered preterm more frequently (OR 1.13, 95% CI 1.06-1.20). This was due to spontaneous (OR 1.30, 95% CI 1.19-1.42) but not iatrogenic (OR 0.96, 95% CI 0.87-1.05) preterm birth. There was an increased risk of pre eclampsia among preterm females. Although males were larger, and male pregnancies were more frequently nulliparous and affected by some other obstetric complications (abruption, urinary tract infection), these did not account for their increased risk. Any effect of growth restriction could not be properly determined. CONCLUSIONS Being male carries an increased risk of spontaneous but not iatrogenic preterm birth. The reasons behind this remain obscure.

Emergency cervical cerclage: Predictors of success

Objective. To document predictors of success of emergency cervical cerclage. Methods. This is a retrospective cohort study of 8 years at a university hospital. Emergency cerclage was defined as when the membranes were at or beyond the external os and was only performed where evidence of infection or labour were absent. Outcomes used were interval between cerclage and delivery, gestation at delivery; a ‘good outcome’ was defined as delivery after 32 weeks and healthy at discharge. Predictive factors for a successful pregnancy outcome were analysed using odds ratios (OR) with 95% confidence intervals. Results. Forty-five emergency cerclages were performed, including 11 twin pregnancies. Twenty-one (47%) had a ‘good outcome’, including two twin pregnancies; 20 (44%) pregnancies reached 36 weeks. In 79.2% of ‘poor outcomes’ chorioamnionitis was found. Prolapsed membranes, advanced cervical dilatation, maternal symptoms and equivocal markers of infection were associated with a poor outcome, but not consistently enough to dictate management. Conclusions. Given the poor natural history of an open external os, emergency cerclage appears beneficial. That this might apply to twin pregnancies has implications for their management. Although success is indeed partly predictable, it can still be achieved even when there is advanced dilatation, prolapse, bleeding or discomfort.

The relation between pre-eclampsia at term and neonatal encephalopathy

OBJECTIVES To determine whether pre-eclampsia, hypothesised to be an inflammatory condition, is associated with fever in term labour, and confirm and examine the reported association of pre-eclampsia at term with neonatal encephalopathy. DESIGN Prospective cohort study. SETTING A Dublin teaching hospital. PARTICIPANTS 6163 women in labour with singleton pregnancies at term at low risk for intrapartum hypoxia, recruited to a randomised trial examining the effect of admission cardiotocography on neonatal outcome. RESULTS Pre-eclampsia was associated with maternal fever > 37.5° in labour (odds ratio (OR) 3.39, 95% confidence interval (CI) 2.1 to 5.4); this was independent of obstetric intervention (adjusted OR 2.07, 95% CI 1.24 to 3.47). Pre-eclampsia was associated with neonatal encephalopathy (OR 25.5, 95% CI 8.4 to 74.7); this too was independent of obstetric intervention (adjusted OR 18.5, 95% CI 5.9 to 58.1). Cord arterial pH values were significantly lower in pre-eclamptics (7.20v 7.24), although severe cord acidaemia was not significantly more common (OR 2.91, 95% CI 0.7 to 9.9). The association of pre-eclampsia with encephalopathy was independent of maternal fever (adjusted OR 16.5, 95% CI 5.1 to 54) and cord acidaemia (adjusted OR 13.5, 95% CI 3.2 to 56.7). CONCLUSIONS The association of pre-eclampsia with maternal fever at term supports the hypothesis that pre-eclampsia is an inflammatory condition. The association of pre-eclampsia with neonatal encephalopathy is independent of obstetric intervention and cannot be explained by either acidaemia or maternal fever. A systemic inflammatory response in the fetus, perhaps secondary to oxidative stress, could explain the link between maternal pre-eclampsia and neonatal encephalopathy, and this may occur through cerebral vasoconstriction.