The milk-making glands in your breasts are divided up into segments, rather like an orange.
Narrow tubes called ducts carry the milk from each segment to your nipple.
If one of the segments isn’t drained properly during a feed (perhaps because your baby isn’t attached properly), this can lead to a blocked duct.
You may feel a small, tender lump in your breast.
“This needs relieving as soon as possible, and your baby may be able to help,” says Halnan.
“If possible, place them with their chin pointing towards the lump so they can feed from that part of the breast.”
Avoid wearing tight clothes or bras so your milk can flow freely from every part of your breast.
Other things that may help include: