Optimal maternal intake and blood levels of vitamin B12 play an important role in fetal development and in health and disease of the offspring. Nonetheless, there is a paucity of data of intake and blood levels of B12 in Canadian pregnant women and in cord blood. We assessed dietary and supplemental intakes using a food frequency questionnaire and serum B12 levels in pregnant women between 12‐16 wks gestation (n=342) and at parturition (n=292) and in cord blood (n=259). Mean intake of dietary B12 was 5.2 ± 3.1 µg/d and 5.2 ± 2.7 µg/d in early and late pregnancy, respectively (RDA= 2.6 µg/d). Additionally, 88% reported using a B12‐containing supplement (usual amount 2.6 µg) during early pregnancy and 83% continued supplement use in late pregnancy. Median serum B12 concentrations in early pregnancy, at parturition and in cord blood were 220 (inner quartile range: 167,289) pmol/L, 167 (131,208) pmol/L and 314 (223,466) pmol/L, respectively. All participants had plasma homocysteine levels in the normal range (<13 µmol/L) during pregnancy. The prevalence of suboptimal serum B12 levels (<148 pmol/L) was observed in 17% and 36% of women in early and late pregnancy, respectively. Our data indicate that suboptimal B12 status, assessed by serum B12 levels, exists in Canadian women during pregnancy despite adequate B12 intakes from diet and supplement use. Whether the observed low maternal B12 levels are functionally significant and impact maternal and fetal health outcomes requires further investigation.