Evaluation of the effects of methanol during early pregnancy in the rat

Recent attention to methanol (MeOH) as a potential alternative fuel prompted an evaluation of the chemical's effects during early pregnancy. Rats were dosed by gavage during Days 1-8 of pregnancy at 0, 1.6, 2.4, or 3.2 g MeOH/kg/day. Groups of animals were killed on Days 9, 11, or 20 of pregnancy, and maternal, embryonic, or fetal parameters were assessed, depending on the stage of pregnancy. The decidual cell response (DCR) technique was also applied to rats treated with MeOH during pseudopregnancy. Reductions in pregnant uterine and implantation site weights seen on Day 9 are the result of MeOH impedance of normal decidualization, as demonstrated by effects on the DCR. An increase in the extravasation of blood at implantation sites seen on Day 9 did not result in an increase in resorptions by Day 20. The 3.2 g/kg/day dose of MeOH produced a reduction in body weight gain by Day 9, which may be considered an indication of non-specific maternal toxicity. No effect on Day 11 or Day 20 embryo-fetal survival, or development was observed.