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

Background: Moderate prenatal alcohol exposure can contribute to neurodevel opmental deficits in nonhuman primate offspring. The purpose of this study was to examine the effects of gestational timing of alcohol exposure on neu robehavior with a nonhuman primate model. Methods: Sixty-three rhesus monkey infants (Macaca mulatta), from four grou ps 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 o r days 0 through 165; and (4) controls, in which mothers voluntarily consum ed an isocaloric control solution on gestational days 0 through 50, 50 thro ugh 135, 0 through 135, or 0 through 165. Data were obtained on offspring f or 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 sig nificantly decreased scores on infant neurobehavioral tests overall in mult ivariate tests, after controlling for birthweight. Univariate tests showed that early gestation alcohol exposure was related to reductions in infant o rientation and motor maturity. Mid- to late-gestation exposure also resulte d in a reduction in motor maturity but did not affect overall neurobehavior al performance in the multivariate tests. Conclusions: Early-gestation alcohol exposure is as deleterious to neonatal neurobehavior as late-gestation or continuous exposure. Moreover, neurobeh avior seems to be a more sensitive marker of early-gestation moderate alcoh ol exposure than growth parameters. Women who are attempting to become preg nant should minimize frequent social drinking, because subtle neurodevelopm ental effects to the fetus may be induced before pregnancy is detected.