A healthy term infant has a physiological weight loss of 5-8% in the early neonatal days due to obligatory reduction of interstitial fluid. With effective breastfeeding, a baby’s weight gain of about 20-35 gram per day is achieved by Day 5 and birth weight is regained by Day 10. (Clinical Guidelines for the Establishment of Exclusive Breastfeeding, International Lactation Consultant Association, 2005)
 
In the first 5 days, this mother had some nipple pain while the baby was suckling. This indicated an attachment problem in the early days. This baby’s lowest weight was 3.25kg. A weight loss of 5.5% occurring on Day 4 was within the normal range. The stool and urine output were good. Both indicated effective suckling despite probable unsatisfactory attachment.
 
After Day 5, the pain had subsided, which reflected no more attachment problem. Her weight gain was good with 40g per day from Day 4 to Day 8 although she had not regained her birth weight by Day 8, which was again within normal limits. The stool and urine output were also good throughout. For exclusively breastfed babies, good weight gain and good output indicate adequate milk intake. In conclusion, breastfeeding was effective.

Since mid-pregnancy, small amount of milk has been produced (lactogenesis I) and stored in the breasts. Milk volume is normally low in the first 2-3 days postpartum. On average, a significant increase in milk volume (lactogenesis II) occurs at 36-72 hours postpartum, when a mother experiences breast fullness and heaviness. This is referred to as milk “coming in”. The following 3-5 weeks is the calibration period, when milk production is calibrated according to her baby’s need. The first 2 weeks are the most sensitive period of milk calibration. Most mothers who start-off having small amount of milk will up-regulate within the calibration period. A minority starting with large amount of milk will subsequently down-regulate. Milk production is mainly under autocrine control, i.e. more milk removal results in more milk production.
 
In the first 2 days of milk coming in, many mothers experience some degrees of breast fullness even after the baby has finished a feed. This physiological breast engorgement or fullness usually resolves within 1-2 days. If there is persistent or even increasing breast fullness after 2 days of milk coming in, the likely causes are ineffective baby suckling, or excessive milk supply in the breast.
 
This mother’s milk came in on Day 3, which was a normal timing. There was no attachment problem after Day 5. Breastfeeding was effective as shown by good urine and bowel output, as well as satisfactory weight gain of 40g per day from Day 4 to Day 8. On Day 8, i.e. 5 days after milk had come in, after the baby had finished a feed on one breast, milk continued to drip from it and the other breast was mildly engorged. This suggested that the mother’s milk supply was more than baby’s need. Fortunately, this mother did not have florid signs or symptoms of engorgement or mastitis.

Based on the principle of autocrine control of milk production, advice on whether the baby should feed on one or both breasts per feed should depend on our assessment of mother’s milk supply. In cases of low supply, we advise feeding on both breasts per feed. For normal milk supply, we suggest a mother to finish one breast first. If her baby needs another breast, she should offer it. For this mother with potential oversupply, we would recommend one breast per feed. If the other breast is very full, she can remove a small amount of milk to relieve her discomfort and to prevent blocking. Expression on a need basis will not lead to oversupply. Probably, a few days later when milk production is further calibrated according to the baby’s need, her breasts would not be so full. By then, she would not need to express her milk anymore.