Judging from the theme and nursery colours she's not going for a gendered colour scheme, so why not just do a bright multicoloured quilt that will work whatever the baby's gender? There's a really gorgeous Robert Kaufman range in a wild variety of colours which includes monkey fabrics. I have some of the abstract fabrics from that range (stripes and squares rather than animals) and they're great. I always do multicoloured non-gendered baby quilts and everyone's loved them so far.
We run to girls in my family. My mother is one of three girls and a boy, and so is her mother. My cousins are three of each, but if you take my aunt, she has two sons and a daughter, and has seven granddaughters with no grandsons (though one isn't biologically related so in terms of genetics, that's six granddaughters). A dietician I knew once said she's known this to happen in other families, and she reckons there may be something genetic going on which causes the male foetuses to be miscarried. I know that my mother had a lot of miscarriages, so perhaps there's something in it.