
Latha and Lavanya. I cant make out if you guys are poking fun at my lactivism or not

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Sylvia, Benjamin is one of those docs who pushes exclusive bfing for 6 months. Like other posters have said before me, breastmilk has all the nutrition your child will need till 6 months. Unless your child is a preemie or of very low birth weight baby, etc. Most paeds would then put your child on a multi-vitamin and Iron because the iron stores in the infants body will get depleted by two months or so.
In my experience with my preemie, I found that most doctors and paeds - even those who followed WHO and UNICEF Innocenti declaration recommendation, urged us to start solids at 4 months. The only reason they had was the child had doubled his birthweight at that time and would need more protein and calcium, etc.
Your doctor does have a point in that breastmilk when compared to cow's milk is more lactose intensive, but that's exactly how evolution meant it to be. The high-lactose, low-protein content is needed to fuel brain development, so I would say go ahead and bf for 6 months.
With K, we found his weight gain was good till he was being exclusively breastfed, the minute we got him on solids it all went out the window. Mainly because of his food sensitivities and that's what exclusive bfing till 6 months offers protection against. There is a hypothesis that the child's gut is open till between the 4 and 6 months to absorb all nutrition needed for the quick growth. Introducing solids at that point could lead the foreign protein being absorbed into the blood stream and triggering allergies.
Incidentally, we did offer solids under much duress from just about everyone around us, after my child turned 6.5 months (or 5 months adjusted), but he really started taking to solids only at 7.5 months or 6 months corrected age...So yeah, the child does know what's good for him.
Follow your child's lead, if you think she is getting very hungry and exclusive nursing is not able to satiate her needs, it may then be time to start solids. The recommendation is around 6 months, it maybe a little early for some kids, like Latha said.