High levels of ethanol (EtOH) consumption during pregnancy adversely affect fetal development; however the effects of lower levels of exposure are less clear.
Our objectives were to assess the effects of daily EtOH exposure (3.8 USA standard drinks) on fetal-maternal physiological variables and the fetal brain, particularly white matter.
Pregnant ewes received daily intravenous infusions of EtOH (0.75g/kg maternal body-weight over 1h, 8 fetuses) or saline (8 fetuses) from 95-133 days of gestational age (DGA, term ~145 DGA). Maternal and fetal arterial blood was sampled at 131-133 DGA. At necropsy (134 DGA) fetal brains were collected for analysis. Maternal and fetal plasma EtOH concentration reached similar maximal concentration (~0.11 g/dL) and declined at the same rate.
EtOH infusions produced mild reductions in fetal arterial oxygenation but there were no changes in maternal oxygenation, maternal and fetal PaCO2, or in fetal mean arterial pressure or heart rate.
Following EtOH infusions, plasma lactate levels were elevated in ewes and fetuses, but arterial pH fell only in ewes. Fetal body and brain weights were similar between groups but relative heart weight was increased after EtOH exposure. In 3/8 EtOH exposed fetuses there were small subarachnoid hemorrhages in the cerebrum and cerebellum associated with focal cortical neuronal death and gliosis
Overall, there was no evidence of cystic lesions, inflammation, increased apoptosis or white matter injury.
We conclude that daily EtOH exposure during the third trimester-equivalent of ovine pregnancy has modest physiological effects on the fetus and no gross effects on fetal white matter development.
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