Drink plenty of water, include high fibre foods in your diet take pear raisins figs etc. If you have just started iron pills it could be due to that. Stop for a couple of days and start gradually. Also let your doctor know so that a mild laxative can be prescribed and you will then have relief. It's not very good to be constipated during pregnancy.

Try remedies for constipation dear.  u will be fine.