Mama, calcium carbonate is usually okay, but since you're asking if someone took it, please check with your doctor kung sino ang kumita nito at bakit, lalo na kung buntis o nagpapasuso, okay? Better safe than sorry talaga, especially pag may health concerns involved. A few of us mums, kami lang nag-coordinate with our OB or pedia before starting anything like that para sure kami na safe for baby din. Let your doctor know lang what was taken and how much, para ma-guide ka ng tama!