Fetal size ni baby

Hi mga momshies! Mejo naconfused ako dun sa fetal size ni baby. Ganito kasi yun every 2 weeks kasi ang balik ko sa OB ko. Eto yung result nung last 2 check ups ko: March 9,2020 BPD: 64mm ; FL: 55mm ; AC: 212mm EDD: June 10, 2020 March 24, 2020 BPD: 74mm ; FL: 52mm ; AC : 220mm EDD: June 17, 2020 As you can see, yung FL (femur length) nagdecrease ng size. Is it possible? Or namali lang ng pagsukat si OB.