My third daughter was 2 this month, still nursing and co-sleeping. I guess when I wean is when I move them to another bed with just their dad. I've always weaned when I've become 4 - 5 months pregnant. So really, the co-sleeping ends only because it's too hard to wean when she's so close in bed with me, and the only reason I strongly wanted to wean is that I was expecting. The first two girls were weaned around 18 - 20 months and slept with their dad for quite a while after that.
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Mina 04/08/2002, Annika 01/02/2004, Yelena 02/22/2006, and one more due 11/06/2008
And Layla is 3 years old today. She's a Boston Terrier, btw. Don't judge She's my first born. She just happens to have a lot more hair than the rest of us