The effects of obstetric medication on newborn behaviour

Abstract

In a study of the effects of obstetric medication on the neonate, 145 mothers and their offspring were studied from 36 weeks of pregnancy to six weeks after the birth. Fifty-one mothers requested intramuscular pethidine, 59 chose epidural bupivacaine and 35 decided not to have drugs. Data were collected during the antenatal period on health, psychological state, and expectations of the coming birth and baby. In the delivery room, observations were made of the infant and his parents, and selected assessments from the Brazelton Neonatal Behavioural Assessment Scale (BNBAS) were performed. The full BNBAS was carried out on days 1, 3, 7, 21, and 42. The Prechtl Neurological Examination (PNE) was done by a paediatrician on day 6. Records were kept by the mother over the first week of her infant's feeding and sleeping pattern, and for 24 hours after the 21 and 42 day visits. A series of questionnaires were also given to the mother during these first six weeks, covering the experience of labour, her mood, and perceptions of the baby.

A multiple regression analysis using "dummy variables" for pethidine and bupivacaine indicated that the mere presence or absence of pain-relief during labour generally had no effect on the neonatal measured used. However, when biochemical indices of drug metabolism in the infant (maternal dose, cord blood concentration in the infant, half-life, and pre- and post-delivery "exposure") were entered into the equation then maternal analgesia and anaesthesia were shown to have consistent and long-lasting effects on the infant. Higher cord levels of pethidine were associated with babies who were more prone to respiratory difficulties, and drowsy and unresponsive immediately after delivery. In the following six weeks depressed attention and social responsiveness were found in connection with high drug levels, as were difficulties in state control at 3 and 6 weeks.

After greater exposure to bupivacaine in utero infants were more likely to be cyanotic and unresponsive to their surroundings in the delivery room. Visual skills and alertness decreased significantly with increases in the cord blood concentration of bupivacaine, particularly on the first day but also throughout the next six weeks. Adverse effects of bupivacaine levels were seen on motor organisation, state control and physiological response to stress. However, the changes involved were relatively subtle, and the failure to find "between-groups" differences suggests that many mothers who received either bupivacaine or pethidine had babies who performed as well, and sometimes better, than those who had not been given drugs.

Sleep and feed patterns and the neurological status of the infant were relatively unaffected by obstetric or medication variables. There were some modest associations between maternal psychological variables and neonatal and parental behaviour in the delivery room, but not over the next six weeks. Neither jaundice nor sex of the baby determined performance on the BNBAS. Discussion focuses on the interpretation of drug effects and the interdependence of psychosocial, obstetric and ecological variables in the management of childbirth.