Gestational age by BPD mm mm 13 10 w 1 d ± 4 d 51 21 w 3 d ± 7 d 14 10 w 3 d ± 4 d 52 21 w 6 d ± 7 d 15 10 w 5 d ± 4 d 53 22 w 1 d ± 8 d 16 11 w 0 d ± 4 d 54 22 w 3 d ± 8 d 17 11 w 2 d ± 4 d 55 22 w 5 d ± 8 d 18 11 w 4 d ± 4 d 56 23 w 1 d ± 8 d 19 11 w 6 d ± 4 d 57 23 w 3 d ± 8 d 20 12 w 1 d ± 4 d 58 23 w 5 d ± 8 d 21 12 w 3 d ± 4 d 59 24 w 1 d ± 8 d 22 12 w 6 d ± 4 d 60 24 w 3 d ± 9 d 23 13 w 1 d ± 5 d 61 24 w 5 d ± 9 d 24 13 w 3 d ± 5 d 62 25 w 1 d ± 9 d 25 13 w 5 d ± 5 d 63 25 w 3 d ± 9 d 26 14 w 0 d ± 5 d 64 25 w 5 d ± 9 d 27 14 w 2 d ± 5 d 65 26 w 1 d ± 9 d 28 14 w 4 d ± 5 d 66 26 w 3 d ± 10 d 29 14 w 6 d ± 5 d 67 26 w 6 d ± 10 d 30 15 w 1 d ± 5 d 68 27 w 2 d ± 10 d 31 15 w 3 d ± 5 d 69 27 w 4 d ± 10 d 32 15 w 5 d ± 5 d 70 28 w 0 d ± 10 d 33 16 w 0 d ± 5 d 71 28 w 3 d ± 10 d 34 16 w 2 d ± 5 d 72 28 w 5 d ± 11 d 35 16 w 4 d ± 5 d 73 29 w 1 d ± 11 d 36 16 w 6 d ± 6 d 74 29 w 4 d ± 11 d 37 17 w 1 d ± 6 d 75 30 w 0 d ± 11 d 38 17 w 4 d ± 6 d 76 30 w 3 d ± 11 d 39 17 w 6 d ± 6 d 77 30 w 6 d ± 12 d 40 18 w 1 d ± 6 d 78 31 w 2 d ± 12 d 41 18 w 3 d ± 6 d 79 31 w 5 d ± 12 d 42 18 w 5 d ± 6 d 80 32 w 1 d ± 12 d 43 19 w 0 d ± 6 d 81 32 w 5 d ± 12 d 44 19 w 2 d ± 6 d 82 33 w 1 d ± 13 d 45 19 w 4 d ± 6 d 83 33 w 5 d ± 13 d 46 20 w 0 d ± 7 d 84 34 w 2 d ± 13 d 47 20 w 2 d ± 7 d 85 34 w 6 d ± 13 d 48 20 w 4 d ± 7 d 86 35 w 3 d ± 14 d 49 20 w 6 d ± 7 d 87 36 w 0 d ± 14 d 50 21 w 1 d ± 7 d 88 36 w 5 d ± 14 d 89 37 w 4 d ± 14 d 90 38 w 3 d ± 15 d