Poor weight gain in breast fed infants can be caused by a number of problems resulting in the common pathway of inadequate milk supply. Infants who have slow weight gain need to be seen by the child's physician or nurse practitioner for evaluation of possible causes. Technique problems are the most common cause of low milk supply. These include mothers who are not feeding their infant frequently enough to get their milk supply up, and infants who have ineffective suckling. Ineffective suckling can result from suckling only on the nipple instead of the areola, from not latching on well or not suckling for a long enough period of time to elevate the prolactin levels.
Nipple shields can interfere with nipple stimulation resulting in low prolactin and oxytocin levels.
Flutter suckling is an abnormal sucking pattern in the infant characterized by rapid shallow tongue movements that do not massage the nipple well enough to stimulate prolactin secretion. Infant health problems such as congenital and acquired infections, urinary tract infections, metabolic diseases such as hypothyroidism or other aminoacidopathies, renal problems, anomalies of the mouth or the throat causing poor sucking, congenital heart disease, cystic fibrosis, congenital neuromuscular disorders, and Down's syndrome can be associated with slow weight gain. Maternal health problems including inadequate maternal diet or hydration, fatigue, anxiety, stress, chronic infections, or endocrine disorders, can interfere with both milk production and milk ejection. A retained placenta can inhibit milk production due to the presence of the placental hormones.