are you breastfeeding? if so, you choice of supplements could be influenced by that. Its common, for up to 6 months after childbirth, to have thinning hair, especially in such a hot summer where we all seem to be moulting like cats round here. Its probably your hormones settling down but maybe you could have your thyroid levels checked too, just in case they are out of whack right now?
all the best and congratulations.