Baby’s abdomen measuring smaller this ultrasound than it did last ultrasound..

Today I had a scan and am 25 weeks along. Last time I had a scan and the abdomen measured in the 24th percentile this time the abdomen measured in only the 16th percentile? Is that possible? The doctor didn’t seem super concerned because last time baby measured in the 13th percentile overall and measured in the 15th percentile overall this time. Has anyone else ever had this happen?