Timing of moderate alcohol exposure during pregnancy and neonatal outcome in rhesus monkeys (Macaca mulatta).

BACKGROUND

Moderate prenatal alcohol exposure can contribute to neurodevelopmental deficits in nonhuman primate offspring. The purpose of this study was to examine the effects of gestational timing of alcohol exposure on neurobehavior with a nonhuman primate model.

METHODS

Sixty-three rhesus monkey infants (Macaca mulatta), from four groups of females, were assessed: (1) an early alcohol-exposed group, in which mothers voluntarily consumed alcohol on gestational days 0 through 50; (2) a mid to late gestation alcohol-exposed group, in which mothers consumed an identical dose on gestation days 50 through 135; (3) a continuous-exposure group, in which mothers consumed an identical dose on days 0 through 135 or days 0 through 165; and (4) controls, in which mothers voluntarily consumed an isocaloric control solution on gestational days 0 through 50, 50 through 135, 0 through 135, or 0 through 165. Data were obtained on offspring for measures of growth and neurobehavior.

RESULTS

There were no effects of alcohol on birthweight, gestation length, or ponderal index. Prenatal exposure to alcohol during early gestation significantly decreased scores on infant neurobehavioral tests overall in multivariate tests, after controlling for birthweight. Univariate tests showed that early gestation alcohol exposure was related to reductions in infant orientation and motor maturity. Mid- to late-gestation exposure also resulted in a reduction in motor maturity but did not affect overall neurobehavioral performance in the multivariate tests.

CONCLUSIONS

Early-gestation alcohol exposure is as deleterious to neonatal neurobehavior as late-gestation or continuous exposure. Moreover, neurobehavior seems to be a more sensitive marker of early-gestation moderate alcohol exposure than growth parameters. Women who are attempting to become pregnant should minimize frequent social drinking, because subtle neurodevelopmental effects to the fetus may be induced before pregnancy is detected.