Breastfeeding specific multi vitamin supplements are expensive and many mothers want to purchase standard multivitamin and mineral supplements. The standard products such as Sanatogen and Centrium are suitable for use. It is important not to take products which claim to be high dose and where the recommended daily amount is reported as in excess of 100% on the label.
The only vitamins needed by breastfeeding mothers are vitamin d 10 mcg/day and folic acid 400mcg/day if no active contraception is being used. Normal diets should provide everything your body needs. Remember babies need vitamin d supplements too according to UK recommendations https://breastfeedingnetwork.org.uk/wp-content/dibm/vitamin%20D%20and%20breastfeeding.pdf
However, we do know that as a new mum finding time to eat properly can be a challenge and a multivitamin is a safety net.
AVOID dose of vitamin A above 700-800 mcg/day and vitamin B6 above 20-50 mg/day. Iodine can concentrate in breastmilk so do not take levels in excess of 100% RDA.
Omega fatty acids are safe in breastfeeding