Although the only things you really need to breastfeed are a baby and a breast, there are a few items you might want to consider buying either during the pregnancy or after your baby is born. These can include:
Expressing, feeding and sterilising equipment
Clothes for breastfeeding
A note on dummies and breastfeeding
Maternity bras are specially designed to support the breasts while breastfeeding. They are elasticised to accommodate changes in the size of the breasts when 'full' and have clips or fasteners on each cup to allow the baby easy access to the breasts for feeding. Many breastfeeding women find they need to wear a maternity bra both day and night (at least for the early weeks), to provide support and help limit any leakage of milk while sleeping. If you plan to launder your clothing daily, then at least 3 maternity bras should be enough. However, if you do not intend to wash your clothes this regularly, then 4 or 5 bras may be needed.
Generally, the breast size you are during the last half of your pregnancy is the size you will be after the birth and you can be fitted for maternity bras during this time. After the birth, the milk 'coming in' does temporarily increase your breast size (for about a week or so), before they settle back to the size they were during the pregnancy (as the milk fully establishes). Maternity bras are designed to accommodate this temporary growth. You can read more in maternity clothes.
Breast pads are small (often circular) pieces of washable cloth (usually a fine terry toweling), or flattened cotton wool pads that are disposable. Breast pads are placed inside each bra cup over the nipples with the aim of soaking up any leaking breast milk. Not every woman needs breast pads (so don't stock up on too many during the pregnancy), but as a general guide: