My first thought is that the difference between 45 minutes and 1.5 hours is quite a bit. As you say, 45 minutes is not unusual at all. If it's more often 1.5 hours then that would be more unusual but not unheard of.
Also, her dd is eating the whole time (not falling asleep and waking up)---and she's quite vigerous!--- She's even pulled her off now and then to check that she's got milk in her mouth--and she does.
Imagine how much energy that must take. What a little eating machine! She's exercising her jaw and mouth muscles so much she'll be able to try a knot in a cherry stalk with her tongue before she's 2!!!
On a more serious note while everything could well be fine and she's just at the long end of the spectrum a very long nursing session
can sometimes be an indicator of a slight latching issue - This is from kellymom:
If baby's latch is shallow, it can be like when you're drinking from a straw and pinch the straw mostly shut - baby is still getting milk but it takes a loooong time at the breast to get enough. Often, even minor changes in latch can help a lot
I would be tempted if I was her to get someone qualified just to cast an eye over her latch to be on the safe side. And if a minor adjustment does help she might save herself a lot of time!!
As for the pumping/bottles thing - I can see why it would be tempting. However although some mothers manage to pump exclusively with a heck of a lot of determination and committment it's not as easy as it might seem. Many of these mums end up struggling to maintain their milk supply. In the first few weeks when the baby feeds at the breast the wave-like movement from their lower jaw (which is not reproduced by a pump) stimulates the production of a hormone called prolactin. This hormone governs milk supply and the levels you produce in the first 6 weeks or so help to govern your milk supply for the rest of your nursing career. This is why it's so crucial to respond to baby's cues at the very beginning. If she was to move to more pumping now this could further put her supply at risk.
Is this something that she will grow out of?
I'm sure she will grow out of it. I would suggest the latching advice because it
might be that with an adjustment she could grow out of it instantly. However if it's not latch and just the way it is reassure your sister it really won't last long and these days will be a blip when compared to all the years of her LO's life she is helping to make healthy and happy. Make the most of the excuse to sit down!!
