There are many different reasons why some women have low supply including: delays in breastfeeding after delivery or separations of mother and baby such as if the baby needs to be admitted to the special care nursery or if the mother is unwell after delivery poor attachment to the breast, which can be caused by flat or inverted nipples, a tongue or lip tie, a sleepy baby because of jaundice, or a difficult or prolonged delivery if the mother is unwell due to problems like mastitis, retained placental tissue or large blood loss after the baby is born scheduled or timed feeding, rather than feeding baby on demand taking an oral contraceptive pill that contains oestrogen formula feeding as well as breastfeeding skipping breast feeds and offering a supplement formula feed but not expressing breast milk at that time to ensure that supply continues to meet baby's demand long-term use of dummies or nipple shields smoking Breast milk supply can be low if the woman has medical problems such as polycystic ovarian syndrome, hypothyroidism, diabetes and pre-diabetes, or takes some blood pressure medications and cold and flu preparations, or has taken the contraceptive pill or has been infertile. In some women, breast or nipple surgery makes breastfeeding difficult. In a few women, the breasts did not change during puberty and early pregnancy in a way that makes breastfeeding easier.