Possible problems associated with the use of nipples shields include a drop in the mother's milk supply and insufficient transfer of milk to the baby. (motherandchildhealth.com)
I decided to try a larger size of nipple shield to know for sure, and sure enough it felt much better right away. (exclusivepumping.com)
If you're breastfeeding during pregnancy, you may have to deal with sore nipples for a little while. (verywellfamily.com)