Patrick J. Pemberton

Predictors of neonatal encephalopathy in full term infants

Abstract Objective: Preliminary investigation of the contribution of adverse antepartum and intrapartum factors to neonatal encephalopathy in singleton neonates born full term. Design: Matched case-control study based on incidence density sampling of controls. Setting: Two major teaching hospitals (one paediatric and one obstetric) and three peripheral maternity hospitals in Perth, Western Australia (population 1.2 million). Subjects: 89 cases, all the full term singleton neonates born during an eight month period in 1992 who fulfilled one or more of six criteria during the first week of life (seizures, abnormal conscious state, persistent hypertonia or hypotonia, and feeding or respiratory difficulties of central origin). One full term control infant without neonatal encephalopathy was matched to each case by sex, hospital of delivery, time of day and day of the week of birth, and maternal health insurance status. Main outcome measures: Odds ratio estimates of relative risk of neonatal encephalopathy associated with antepartum and intrapartum factors. Results: Estimated incidence of moderate or severe encephalopathy in first week of life was 3.75 per 1000 full term live births. Thirteen cases and no controls had evidence suggestive of important intrapartum hypoxia, and in only five of these cases was the neurological condition at birth attributed to events during the intrapartum period. Univariate conditional logistic regression analysis identified significant differences between cases and controls for maternal vaginal bleeding in pregnancy, maternal thyroxine treatment, congenital abnormalities, induction of labour, interval from membrane rupture to delivery, maternal pyrexia in labour, augmentation of labour, abnormal intrapartum cardiotocograms, and meconium in labour. Family history of convulsions also approached significance. Conclusions: Our preliminary results suggest that intrapartum hypoxia, according to currently used criteria, was not the cause of neonatal encephalopathy in most cases in this population. Our findings suggest that many aetiologies of neonatal encephalopathy originate in the antepartum period.

Neonatal subgaleal haematoma: Associated risk factors, complications and outcome

Objective: To describe the obstetric and perinatal factors, in particular the method of delivery, associated with development of a subgaleal haematoma (SGH) and to determine the outcome of survivors with this type of birth trauma.

Rising Incidence of Gastroschisis in Teenage Pregnancies

A population-based incidence of gastroschisis using the unique characteristics of a geographically isolated state with a single tertiary obstetric and pediatric hospital has been developed via retrospective data review. Sixty-four cases of gastroschisis were identified during the period 1980 to 1993. With 332,530 deliveries in the 14-year review period, the population incidence of gastroschisis is 1.80 per 10,000 births (95% CI 1.40-2.32). There has been a rise in incidence from 0.48 per 10,000 births in 1980 to 3.16 per 10,000 births in 1993 (NS). This alteration in incidence is an age-group specific event. The age group 15-19 years, which accounts for a consistent 6.5% of total deliveries, has 10 times the incidence of the age range 25-29 years. A sharp rise in the occurrence of gastroschisis in women 15-19 years was observed, with the incidence increasing from 4.0 to 26.5 per 10,000 births over the period of review. Increased use of prenatal ultrasound has made antenatal diagnosis usual and consequent referral to the tertiary referral hospital for delivery. There was a 46% incidence of smoking, and 19% of women admitted to recreational drug use. A strong association with preterm delivery and low birthweight was present with a 50% incidence of low birthweight, eight times the state incidence (OR 14.82, 95% CI 8.97-24.51). The rate of preterm birth was 46.1% vs. 6.6% in the general obstetric population (OR 12.11, 95% CI 6.45-22.73). There was a high incidence of perceived fetal distress, reflected in an increased rate of emergency cesarean section (23% vs. 8%, OR 4.31, 95% CI 1.91-9.74). The early neonatal outcome was satisfactory with three neonatal deaths and an overall perinatal survival rate of 85%. The increase in incidence of gastroschisis in this population-based study reveals a strong association with young maternal age. Investigation into possible etiologic factors to explain this observation is required.

The intrapartum CTG prior to neonatal encephalopathy at term: a case‐control study

Objective To compare cardiotocograph (CTG) records during labour in cases of neonatal encephalopathy and matched controls.

Birth defects in children with newborn encephalopathy.

This study was designed to investigate birth defects found in association with newborn encephalopathy. All possible birth defects were ascertained in a population-based study of 276 term infants with moderate or severe encephalopathy and 564 unmatched term control infants. A strong association between birth defects and newborn encephalopathy was found with defects affecting 27.5% of children with encephalopathy and 4.3% of control children (odds ratio 8.55; 95% confidence interval 5.25 to 13.91;p<0.001). In 11.8% of infants with a birth defect the defect was not diagnosed until after the newborn period, illustrating one of the difficulties in attempting to exclude infants with birth defects from studies of newborn encephalopathy. The majority of defects (89%) were not specific anomalies of the CNS. In 36.8% of children with encephalopthy who had a birth defect, the defect was considered to be the probable cause of the encephalopathy. Infants with birth defects who had encephalopathy had a poorer prognosis than those without: they were twice as likely to die by the age of 2 years and three times more likely to have cerebral palsy. This study catalogues the spectrum of birth defects associated with newborn encephalopathy and illustrates the importance of their inclusion when investigating both the aetiology and outcome of this condition.

Newborn encephalopathy in term infants: Three approaches to population-based investigation

Epidemiological studies of abnormal neonatal neurology—newborn encephalopathy—are of value not only because of their intrinsic interest, but also because newborn encephalopathy as a potential indicator of the quality of intrapartum care needs to be evaluated. As newborn encephalopathy has a closer temporal relationship to the exposures of interest than does cerebral palsy, it would have a significant advantage over cerebral palsy as an index of intrapartum care. However, the proportion of newborn encephalopathy cases which arise in labour needs to be determined accurately before we can contemplate using the occurrence of newborn encephalopathy as such an indicator. Few good epidemiological studies of newborn encephalopathy have been carried out and there are many challenges in elucidating its antecedents. This paper reviews these challenges and briefly describes and contrasts three ongoing studies.

Neonatal herpes simplex infection: Keys to early diagnosis

Objective: To highlight the clinical features of neonatal herpes simplex (HSV) infection that might facilitate earlier diagnosis.

Gastric Perforation Associated with Indomethacin Therapy in a Pre-Term Infant

This is a case report of a pre‐term infant who developed a gastric perforation fifteen hours after receiving oral indomethacin treatment for the pharmacological closure of a patent ductus arteriosus. This observation of a possible causal relationship between indomethacin and gastric perforation reaffirms the need for caution when using this drug in pre‐term infants.

Gentamicin in the newborn

Serum gentamlcin assays were performed on 116 paired samples of sera from 99 infants, whose birthweights ranged from 740 g to 4400 g.

INTRAPARTUM RISK FACTORS FOR NEWBORN ENCEPHALOPATHY : THE WESTERN AUSTRALIAN CASE-CONTROL STUDY

OBJECTIVE To identify intrapartum predictors of newborn encephalopathy in term infants. DESIGN Population based, unmatched case-control study. SETTING Metropolitan area of Western Australia, June 1993 to September 1995. SUBJECTS All 164 term infants with moderate or severe newborn encephalopathy; 400 randomly selected controls. MAIN OUTCOME MEASURES Adjusted odds ratio estimates. RESULTS The birth prevalence of moderate or severe newborn encephalopathy was 3.8/1000 term live births. The neonatal fatality was 9.1%. Maternal pyrexia (odds ratio 3.82), a persistent occipitoposterior position (4.29), and an acute intrapartum event (4.44) were all risk factors for newborn encephalopathy. More case infants than control infants were induced (41.5% and 30.5%, respectively) and fewer case infants were delivered by caesarean section without labour (3.7% and 14.5%, respectively). Operative vaginal delivery (2.34) and emergency caesarean section (2.17) were both associated with an increased risk. There was an inverse relation between elective caesarean section (0.17) and newborn encephalopathy. After application of a set of consensus criteria for elective caesarean section only three (7%) eligible case mothers compared with 33 (65%) eligible control mothers were sectioned electively. Of all the case infants, 113 (69%) had only antepartum risk factors for newborn encephalopathy identified; 39 (24%) had antepartum and intrapartum factors; eight (5%) had only intrapartum factors; and four (2%) had no recognised antepartum or intrapartum factors. CONCLUSIONS The causes of newborn encephalopathy are heterogeneous and many relate to the antepartum period. Elective caesarean section has an inverse association with newborn encephalopathy. Intrapartum hypoxia alone accounts for only a small proportion of newborn encephalopathy. These results question the view that most risk factors for newborn encephalopathy lie in the intrapartum period.