After about 20 to 24 weeks of the pregnancy, the woman's breasts start to produce colostrum or the 'first milk'. Some women may notice this 'early milk' leaking from their breasts in the last weeks, or months of their pregnancy. The colostrum remains present for about the first 48 hours after the birth. If you try to hand express colostrum (although not every women is able to express colostrum), it can look like a clear, or creamy yellow, substance that is syrupy in consistency. It is normal only to get a few drops of colostrum out at one time. A drop or two of colostrum may still be expressed from the breasts of women (and grandmothers) years after they have their baby, even if they do not ever breastfeed.
Some women decide to initially breastfeed their baby in the first 24 - 48 hours to give their baby the benefits of the colostrum. This is because it is high in protein and contains substances such as fat- soluble vitamins, and anti-infective agents, or 'antibodies' that are designed to help provide protection for the baby until their own immune system matures. Other women will breastfeed for a few days, or a few weeks, or start to bottle-feed once the colostrum changes to what is known as 'mature milk', (or when the milk 'comes in'). The milk will usually 'come in' about 48 to 96 hours (or 2 to 4 days) after the birth. Stimulation of the nipples through the feeding of colostrum, will usually make the milk come in earlier, within 48 to 72 hours.