No, co-feeding does not deprive the newborn of colostrum benefits as long as it is in demand. The presence of another breastfed child might even encourage the production of colostrum and make breastfeeding easier.
Colostrum is the first milk which the newborn has access to after birth. Its production begins in the second trimester of pregnancy under the effect of the placental hormones (estrogen and progesterone). At birth, the newborn exclusively drinks the colostrum made especially for him during the first three to four days of life. It is possible that the production of colostrum last even longer, thanks to the stimulation of the older child who is still breastfeeding. After the colostrum, mature milk production will start rapidly, stimulated by breastfeeding and the hormonal changes associated with childbirth. These changes are mainly related to the placenta and the hormones it secretes.
After four months of pregnancy, placental hormones decrease the production and ejection of mature milk. Since the amount, taste (due to the preparation of the colostrum) and ejection of milk are modified according to the needs of the unborn child, some children naturally lose interest in breastfeeds. However, if children continue to be breastfed throughout pregnancy, it becomes important to ensure that they meet their needs by introducing solid foods such as meat, cereal products, vegetables and fruits, if taking solid food is appropriate for their age. An infant formula may be appropriate if the breastfed child is still very breastmilk-dependent. For more on this topic, click here.
If the older child is occasionally breastfed, it is not necessary to take special measures to ensure that the baby gets enough colostrum. However, to ensure sufficient growth in infants and to make the most of colostrum, it is best to breastfeed before the older child and change breasts regularly if they are still very breastmilk-dependent. A few days after delivery, the production of mature milk gets back on track. In case an older child continues to breastfeed often, it is important to consider that breastfeeding needs of infants predominate over those of the elder.
The fact that the elder stimulates the breast usually results in more rapid onset of mature milk, but it should contain high proportions of colostrum for a longer period. Moreover, the process of lactation could bring less congestion problems through drainage of the older child. The production is then adjusted to the demand of the two children as is usually the case in other nursing situations, such as with twins.