vitamin b12 injection therapy Injections at Olympia B12 Shots vs. IV Infusions:

Best administered in the morning

Therefore, parenteral cyanocobalamin should be administered to a pregnant woman if the benefits outweigh the risks.[15][16] Cyanocobalamin is excreted in the breast milk of nursing women in levels similar to the level of vitamin B12 in maternal plasma.[25] The distributed cyanocobalamin in breast milk has been found to be compatible with breastfeeding by the American Academy of Pediatrics.[26] In addition, there has not been any reports of adverse effects associated with the intake of normal daily requirements of vitamin B12 during lactation

Thats the protein in your red blood cells that helps carry oxygen throughout your body

If low B12 explains fatigue and weight loss, replacement will likely restore health and weight