Effect of intrapartum meperidine on the behavioral consequences of neonatal oxygen deprivation in rhesus monkey infants.

The endogenous opiate system is thought to play a unique role in the adaptive response to hypoxia during the fetal and neonatal period. Exogenous opiates used as analgesics during labor may also affect this adaptive response. Infant monkeys (Macaca mulatta) were exposed to oxygen deprivation (15-min period breathing 12% O2) on the day of birth. One half of the infants had been exposed to meperidine during parturition via treatment of the dam (2 mg/kg, i.v.). An additional control group received neither treatment. All infants were evaluated for growth, development and neurobehavioral performance over a subsequent 14-week period. Compared to controls, infants exposed to oxygen deprivation had somewhat slower weight gains during the early neonatal transition from weight loss to weight gain, were less responsive to sensory stimulation on the day of the oxygen deprivation episode, slept more on the first night after the episode, had fewer active and mature behaviors during a 3-week period of rapid motor development, and had impaired fine motor skills. Prior exposure to labor analgesia apparently prevented many of these effects. Use of opiate drugs during the perinatal period needs to take into account the unique properties and functions of the endogenous opiate system during this developmental period.