Effects of chronic caffeine consumption in pregnant monkeys (Macaca fascicularis) on blood and urine clinical chemistry parameters.

Pregnancy requires a variety of physiological adaptations to create an environment for the optimal development of the fetus. The widespread consumption of the methylxanthines especially caffeine and to a lesser extent theophylline by pregnant women suggests that it is important to determine whether these methylxanthines may influence maternal physiology during pregnancy. Forty female monkeys (Macaca fascicularis), randomly divided into three groups, were exposed to caffeine in their drinking water (0, 0.15, or 0.35 mg/ml) before, during, and after pregnancy. This exposure resulted in a dose-related increase in reproductive failure in the form of stillbirths, miscarriages, and decreased maternal weight gain. Blood and 24-hr urine samples were collected every 2 weeks for clinical chemistry analysis. There were a number of both pregnancy-related changes and treatment-related effects on the clinical chemistry measures. As expected, serum cholesterol and triglyceride levels declined during pregnancy for all dose groups but there were no treatment-related effects. Serum and urine creatinine levels were increased in both treated groups. Serum glucose levels, which usually decline during pregnancy, remained elevated in the high-dose group. Serum estrogen levels in the high-dose groups were depressed compared to those of the other two groups. These changes indicate that elevated serum levels of caffeine and its metabolites, particularly theophylline, may influence maternal physiology during pregnancy in the monkey.