Hello! Your very welcome and honestly, this is just a wonderful forum for support isn't it?
To answer a few of your questions... NWs do become more frequent during the 4mth SR. Yes it can be due to hunger since there is a GS around this time. During the 4th month, I honestly treated every NW with a feed. I nurse as well. In time, the NWs passed. It is also possible developmental as well during this time
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...if you can, please post your EASY. Jot it down for a good 3 days and post it. Maybe there is something we can add to help. How frequently is he waking at nights? I also noticed mine had a good leap in A times during the 4th mth too. All babies vary of course but mine took a bit of a leap.
Are you having supply issues? Or what do u mean low supply? ...honestly we started getting 8+ hrs of sleep around the start of the 5mths after the regression. BUT, breast fed babies I feel is very common to still wake at least once for a feed still. So if he wakes, I would continue to feed. If he starts his long stretches and then he wakes before then, after having slept straight for awhile, then I would try comforting and resettling before offering a feed by that time. Make sense? So if he sleeps at 7pm and then wakes at 9pm but is on a 4hr, chances are it's not hunger. I would resettle. If for a few weeks he has been doing 6+ hrs stretch, then wakes before then all of a sudden- I would also resettle then. Keep in mind that there are always growth spurts as they grow.. Sometimes they will wake and be hungry. So you'll then know to add extra feeds or increase solids etc. kwim? ...how long as he been on 4hr easy? For a breast fed baby, that's early. I don't think we hit that till a bit later. Is he exclusively BF? ...you may want to make sure he's getting enough in his day especially being on a 4hr easy. How many feeds per day? Is he average on his weight etc?
As far as teething, I guess that's your call. If you see him gnawing away more than usual and getting fussy/bothered, I would medicate. Form of medicine is up to you. They also have teething pellets and things of that nature if your not comfortable with Tylenol etc.
The swaaaaaddle... During the 4mths it gets tricky!!! Thanks to another part of the regression- they become so mobile! Many begin rolling too and that's when one has to start working w that swaddle. They are ready to be weaned but aren't ready to sleep without it haha! We had such a difficult time w/ the swaddle! He also used the miracle blanket. He started rolling... One. Two, he used a paci back then so I was trying to wean gradually- u know, one arm at a time thing... But he kept grabbing at his paci and disturbing his sleep. The swaddle had also begun to disrupt his sleep as he was fighting against it or kicking his feet out and would wake. After attempting the gradual way for a few weeks, I just removed it entirely and AP his sleep. I did this w naps first. Eventually bedtime. It's a process. But many start with one arm out for a few days then the other arm, legs etc. I started with legs first.. Since that what he always had out anyway
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good luck! Many aren't ready either- if he isn't just wait a few more days.
Many hugs!