Breast Implants Nipples

My friend is 37 weeks pregnant. Her breast have become really sore this week and her nipples hurt really bad.?
Today one nipple feels better but the other is still really sore. Is this normal or is something wrong? (she got Breast Implants two years ago) her nipples have also just begun to darken Is the baby coming soon?
its perfectly 100% normal. nipples do darken and become heavy and sore, milk can even start leaking, it not a sign she be having the baby real soon but it does happen near the end of pregnacy in the third trimester.
Skin and nipple sparing mastectomy with implant