Reduced Cardiac Sympathetic Activity and Subclinical Vitamin B12 Status among Indian Mothers During Early Pregnancy

Authors : Sharma S, Sucharita S, Ramiah R, Thomas T, Raja S, Sheela CN, Srinivasan K

Publication Year : 2018

Abstract :

OBJECTIVES:
Prevalence of subclinical vitamin B12 deficiency is high during early pregnancy especially among Indian women. Early pregnancy is also associated with modulations in autonomic nervous activity to adapt to haemodynamic changes. Current study aimed to compare the autonomic nervous activity through heart rate variability (HRV) indices during early pregnancy in women with low and high vitamin B12 status.

METHODS:
Forty-two healthy pregnant Indian women in their early pregnancy (less than 14 weeks) were evaluated. Blood samples were analysed for plasma vitamin B12, haemogram and ECG. ECG was subjected to heart rate variability analysis. Subjects were divided into four groups based on quartile values of vitamin B12 levels.

RESULTS:
There was a significant difference in Log LF (low frequency) HRV between the study groups (p=0.03). Log LF HRV was lower in lowest vitamin B12 group (Quartile 1 of Vitamin B12 levels less than 151.7 pmol/l) compared to group with highest vitamin B12 levels (Quartile 4 of Vitamin B12 levels greater than 248.7 pmol/L) (p=0.05). There was a significant positive correlation between plasma vitamin B12 levels and Log LF (r=0.36, p=0.02).

CONCLUSION:
This study showed reduced sympathetic activity among subjects with low vitamin B12 status compared to subjects with high vitamin B12 status. Thus, emphasising the use of vitamin B12 levels during routine clinical evaluation and utility of simple measures like HRV as a screening tool during pregnancy along with postural blood pressure evaluation to rule out orthostatic intolerance. Further, longitudinal studies are required to evaluate vitamin B12 status and its long-term impact on autonomic nervous system during pregnancy.