DS2 exclusively BF. Was born on 91st centile on charts. Has been following the 98th centile. This week when I got him weighed he has dropped to just below the 91st centile. HV seemed not worried at all. She said babies often plateau out at 4 months.
Should I be worried about his lack of weight gain?
No - it is totally normal for BF babies to plateau at this stage. Your HV is (in this instance!) right. Check out the new WHO growth charts, based on milk-fed babies www.rcpch.ac.uk/. It sounds like you have a fantastic baby, who is hale and hearty, and nothing to worry about!
My boys, exc. BF, leapt a centile every weigh in til about 12 weeks, when they started to plateau, with one dropping a centile at 14 weeks. They are totally good and have continued to grow well at a more steady pace.
Try and not worry too much about weight gain per se, instead trusting your instincts that your baby is feeding well, is content and is developing as you'd like him to be.
I stopped regular weigh-ins at 14 weeks as I felt it was important to be using my natural intuition more. I got them weighed again at 22 weeks, out of curiosity, and have no set plans for when I will do so again!
DS (6m) stuck to 50th centile up until 4m then dropped to 25th and now between 25th & 9th. I asked around after fretting for a bit and it seems to be quite common - it seems to co-incide with being much more aware of the world and distracted during feeding and also getting more active. DS is fine and dandy, weeing and pooing and meeting his milestones so I've been reassured by my HV - and by MNers - not to worry.
So, in short, if your DS seems well and happy then no, don't worry
My DS (b-fed) is small, he was on the 3rd centile and started dropping off the line a bit three weeks ago (at nearly four months), the HV at the weighing clinic made DH feel terrible by saying in front of everyone that the baby is not gaining enough weight. Since then we have been stuffing the little sausage wih milk every time he moves, his next weighing is on Monday and we hope things will have improved as we have been very worried (although he is a very happy healthy looking baby despite being small). It is somewhat reassuring to hear of other babies that have also dropped off their line a bit at this stage.