Somatic development of the infant monkey following in utero exposure to caffeine

Caffeine has been associated with a number of reproductive and developmental effects in animals and humans. In an effort to characterize the potential effects of caffeine on the developing infant, 40 adult female monkeys (Macaca fascicularis) were randomly divided into three groups and exposed at 0, 0.15, and 0.35 mg/ml (equivalent to 0, 10-15, and 25-30 mg/kg/day, respectively) of caffeine via their drinking water, before, during, and after pregnancy. Maternal blood and milk samples were collected following parturition. Infants were separated from their mothers within 12 hr of birth and were reared in a primate nursery. Blood samples were collected during the first week of life, and body weight, somatic measurements, and food consumption data were collected throughout the first 3 years. Maternal blood and milk concentrations and infant blood concentrations of caffeine and theophylline (the major blood metabolite of caffeine in the monkey) were similar to one another. Infant half-life of these methylxanthines was longer than that of the adult but not as long as that observed in human infants. Body weights and somatic measurements of male infants were significantly reduced over the first 30 days, as were a number of initial somatic measurements in both male and female infants. These deficits were not evident after 1 year of age. There were no treatment-related effects on infant tooth eruption or milk consumption. Results from this study support previously published results from this group of monkeys as well as studies by other researchers in rodents indicating that caffeine consumption during pregnancy can alter infant somatic development.