It is common for the nipple and areolar to develop changes to the skin color ("pigment") during lactation, whether breastfeeding or pumping or a combination of both.
Physician Guide to Breastfeeding for Parents, Physicians
Vasospasm - Physician Guide to Breastfeeding
Cracked Nipples Symptoms, Causes & Common Questions
Bodily Nip SOS: Breastfeeding Ointments for Nipples & Breast Pads
Breast changes after pregnancy and during breastfeeding
When to Change Nipple Size: Tips to Choose the Best Bottle
Nipple Color Changes During Breastfeeding - Physician Guide to
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Nipple Vasospasm (White Nipple): Symptoms, Treatment & Tips
Nipple discharge Information
The Color of Breast Milk and How It Changes