Background: There are limited studies on biochemical and haematological response to vitamin B12 supplementation in pregnant women with vitamin B12 deficiency in literature.

Aim: To evaluate the biochemical and haematological response of vitamin B12 supplementation in pregnant women with vitamin B12 deficiency anaemia.

Method: Thirty pregnant women with macrocytic anaemia due to vitamin B12 deficiency with gestation <36 weeks, Hemoglobin <10.0 gm/dl, MCV > 100 fl, platelet count >30,000 cells/mm3 withno other comorbidity were administered a single dose of 1000 μg of vitamin B12 intramuscularly. Blood samples were subjected to complete blood count with peripheral smear, reticulocyte count and vitamin B12 levels before and 4 weeks after vitamin B12 administration.

Results: Majority (90%) were multigravida and 90% were vegetarian. Fatigue was the commonest complaint (70%). Mean Hemoglobin improved from 8.76 ± 0.65 to 10.53 ± 0.63 gm/dl, TLC increased from 5483.33 ± 866.65 cells/cumm to 7726.66 ± 1275.75 cells/cumm, platelet count improved from 1.86 ± 0.44 lac cells/cumm to 3.16 ± 0.66 lac cells/cumm, MCV decreased from 102.1 ± 1.6 fl to 96.4 ± 1.55 fl. Mean MCH decreased from 32.87 ± 0.65 pg to 29.39 ± 0.7 pg. MCHC changed from 32.18 ± 0.85 gm/dl to 30.47 ± 0.84 gm/dl, Reticulocyte count increased from 0.52 ± 0.14% to 0.78 ± 0.18% and vitamin B12 levels improved from 189.83 ± 10.85 pg/ml. to 435 ± 107.91 pg/ml. The difference was statistically significant, P < 0.001 for all values).

Conclusion: A single dose of 1000 μg vitamin B12 intramuscular administration results a statistically significant increase in serum vitamin B12 levels in pregnant women with vitamin B12 deficiency anaemia.