One thing is perfectly clear with my children. They have big 'ol noggins! My youngest, who was 11 weeks early (so who is almost 1 year actually, but about 9.5 months adjusted), always falls within the 90-95th percentile for head circumference when they compare him to children his actual age (so other 1-year-olds, in this case). In fact, I ordered him a hat for Christmas and bought the 12-24 month size. I'll be lucky if it lasts him through the rest of this winter! So, I don't expect this next little peanut to be any different. Since she's going to be a winter baby, she's definitely going to need some hats. I might just do what Plucky's Second Thought did and make some so that I KNOW they'll fit.
See the Adorable Knotted Baby Hats.