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Pre-natal events and later infant behaviour

Journal of Psychosomatic Research
Publication Date
DOI: 10.1016/0022-3999(77)90003-4
  • Biology
  • Medicine
  • Psychology


Abstract In principle, individual differences in the behaviour of infants at birth can be determined (a) by genetic endowment, (b) by intrauterine environment and (c) by factors associated with medical surgical intervention during labour and delivery. These three factors may interact. In addition, uterine environment may be influenced by maternal variables ranging from maternal height to the mother's psychological state during pregnancy, and maternal variables operative during pregnancy may be influenced by the mother's life experiences before the pregnancy. Recent research on sources of individual differences in the behaviour of infants in the neonatal period has tended to concentrate on the possible effects of drugs given during labour and delivery, and in recent years, a method widely used for assessing the infant's behaviour in the neonatal period has been the Brazelton Neonatal Behavioural Assessment Scale (Brazelton 1973). This assessment is in effect a behavioural examination lasting about half an hour, during which the infant is rated on its response to a variety of physical and social stimuli. The studies which have used the Brazelton examination to look for effects on the infant's behaviour of drugs given at delivery show conflicting results. While some authors have reported significant adverse effects, others, including Brazelton et al in a more recent study (in 1976) have shown only very minor drug effects. Brazelton et al conclude that either the effects of drugs are indeed minimal or that the techniques of the Brazelton examination are not appropriate for their detection. In a study of 50 first-born infants (30 male and 20 female) examined by means of the Brazelton examination on the 6th day of life in hospital, we also have looked at the effect of drugs given during labour and delivery. However, since ours is not specifically a drug study, but an attempt to identify sources of individual behaviour differences of whatever origin, we have also looked for associations between Brazelton test results and a number of other factors, including those pro and peri-natal factors which Butler and Alberman (1969) have shown to be associated with increased perinatal mortality. Such factors may reasonably be expected to leave some consequences in those infants who are less severely affected. They include the age, height and social class of the mother, smoking and pre-eclamptic toxaemia. We have examined our Brazelton test scores in relation to these variables and some results will be presented. As part of a prospective study of childhood disturbance using a combined epidemiological and observational approach (for details, see Wolkind, Hall and Pawlby, in press), 50 babies born in the two hospitals of an Inner London Borough were tested, in hospital, on the 6th day of life, using the Brazelton Neonatal Behavioral Assessment Scale (Brazelton 1973). The Brazelton Assessment was selected in preference to a neurological examination because the Brazelton Assessment appears to test aspects of the everyday behaviour of babies which are likely to be of immediate importance to mothers and to the developing mother-infant interaction. Many pre- and peri-natal variables are now suspected or known to affect the outcome for the child, either during the newborn period or later in childhood (Butler and Alberman, 1969, Davie, Butler and Goldstein, 1972, review in Illingworth 1975). In our Brazelton sample, which was selected without knowledge of the birth history, we controlled only for parity (all first-born), race (all Caucasian), marital status of the mother (all married or cohabiting) and birth-weight and general health of the baby (none under 2400 g. at birth and none in special care at the time of testing). Social class was also largely controlled for, since 84% of the sample were working class (Class III manual and below). In respect of other pre- and peri-natal variables, however, our sample was heterogeneous and there was a high incidence of maternal short stature, mother under 20 years old, smoking in pregnancy, pre-eclamptic toxaemia, oxytocin-induced or assisted labour and forceps deliveries. 84% of the mothers received Pethidine in labour (mean dose c. 150 mg) but epidurals were exceptional (4%). Following the argument that the baby's condition at birth may provide a summary measure of the effects of all the pre- and peri-natal events to which the foetus has been subjected, and prompted by Ucko's finding (Ucko, 1965) of a relationship between newborn anoxia and later behaviour, we looked first for relationships between our Brazelton scores at 6 days and the Apgar respiration score. Babies with an optimal respiration score (a respiratory effort rating of 2 at 1, 5 and 10 minutes after birth) were contrasted with babies with a non-optimal score, and the following Brazelton measures were examined: habituation to light, habituation to rattle, startle, tremors, pull to sit, defence against cloth, al rtness, response to face, response to voice, response to face and voice, peak of excitement rapidity of build-up, irritability, consolability and predominant state. Of these, two items showed a statistically significant relationship with the Apgar respiration score. These were peak of excitement (P=.023) and lability of states (P=.036). Babies with a sub-optimal respiration score at birth reached a higher level of arousal during the Brazelton examination at 6 days and also showed greater lability of states during the examination. As a second step in our analysis, we looked for more direct associations between pre- and peri-natal factors and behaviour at 6 days. Relationships were sought between scores on the 16 individual Brazelton items listed above and the following potentially relevant pre- and peri-natal factors: maternal height, maternal age, maternal social class, smoking in pregnancy, pre-eclamptic toxaemia, labour induced or assisted by oxytocin, length of labour, drug score for labour and forceps delivery. Pre-eclamptic toxaemia was rated “mild” if at any point in pregnancy diastolic blood-pressure had exceeded 90 and “severe” when in addition, there was a hospital diagnosis of toxaemia (c.f. Butler and Alberman, 1969). The drug score for labour was compiled by assigning one point for each 50 mg of Pethidine received (a simplified version of the scoring system

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