Very good question and I understand your concern. Iron and calcium are required to meet growing demands of body during pregnancy
(as long as you breast feed your baby). Rest assured it won't cause any damage to your complexion. During pregnancy hormonal
changes may give rise to dark spots on cheeks, known as "Melasma" . That will fade after the delivery. If not one may consult a deermatologist.
I thank you very much again for submitting your question. I hope you find my response to be helpful and informative. If you have any additional concerns I would be happy to address them.