The conventional wisdom and common recommendation is to supplement with calcium, but I saw at least one study stating that it is not necessary: https://pubmed.ncbi.nlm.nih.gov/9584497/
I rather suspect that if you are already eating a diet deficient in calcium, breastfeeding may exacerbate the issue, and since the supplements tend to have a poor bioavailability, taking them even if you don't need to isn't going to be harmful. Eat a healthy balance of foods and you are probably fine.
I may have a nurse for a mother, but I am very much not a doctor.
I rather suspect that if you are already eating a diet deficient in calcium, breastfeeding may exacerbate the issue, and since the supplements tend to have a poor bioavailability, taking them even if you don't need to isn't going to be harmful. Eat a healthy balance of foods and you are probably fine.
I may have a nurse for a mother, but I am very much not a doctor.