Obstetric analgesia and infant outcome in monkeys: infant development after intrapartum exposure to meperidine or alfentanil.

Infant monkeys (Macaca mulatta) exposed to narcotic analgesics during labor after treatment of dams were evaluated for growth and development over a 14-week period. Ten infants exposed to meperidine (2 mg/kg maternal dose) or alfentanil (0.1 mg/kg maternal dose) were compared with seven controls whose dams received no analgesic. No group differences in weight gain or body growth were observed. Alfentanil-exposed infants appeared to have a higher incidence of infections requiring veterinary treatment. Measures of spontaneous activity showed a significantly higher incidence of immature rest pattern (laying) in the alfentanil group associated with lower overall locomotor activity relative to controls. Meperidine-exposed infants had a generally higher overall level of locomotor activity than controls that was statistically significant at 11 weeks of age. Alfentanil-exposed animals were impaired in performance of a simple cognitive task (object constancy) at 2 to 3 months of age and meperidine-exposed infants showed a similar nonsignificant trend. Gross and fine motor maturations were similar to those of controls. Thus, in this situation, the impact of obstetric analgesic treatment was demonstrable for several months after birth in some limited areas.