How long after pregnancy do you use whitening strips again? Congratulations on your new baby! Now that you have finished pregnancy and breastfeeding, you may be eager to re-brighten your smile with teeth whitening strips during pregnancy . But how long should you wait to start using whitening strips again after giving birth? The dentist in Rancho Cucamonga , CA , advises waiting at least 3-6 months postpartum before resuming over-the-counter whitening strip kits. Here's why, along with tips for safely brightening after having a baby. Why Wait After Pregnancy to Whiten Teeth? There are two main reasons to wait to use whitening strips again after you complete pregnancy and breastfeeding: 1. Avoid Passing Peroxide to Baby – Whitening products contain low hydrogen or carbamide peroxide levels. While the amounts are small, waiting until breastfeeding is finished before using whitening strips again is ideal. It gives time for concentrations to clear your milk ducts fully. 2. L