Biparietal Diameter (BPD)

                Chervenak FA, Isaacson GC and Campbell S (eds).

                   Ultrasound in Obstetrics and Gynecology, 1992;

             Table A1-2:pg 1778.  Boston: Little Brown and Company

 

GA

(wks)

-SD

Mean

+SD

 

12

18.5

20.6

22.5

13

21.5

23.8

26.1

14

26.4

28.8

31.2

15

27.8

30.4

33

16

31.6

33.9

36.2

17

37.8

38.4

41

18

38.4

41.1

43.8

19

42.1

43.9

45.7

20

44.1

47

48.9

21

47.3

50.1

52.9

22

49.9

53.1

56.3

23

53.6

57.3

61

24

56.1

59.5

62.9

25

59.6

62.1

64.6

26

62.7

65.9

69.1

27

66.4

70.1

73.8

28

70

72.8

75.6

29

71.6

76.4

79.6

30

74.2

76.8

79.4

31

76.2

79.8

83.5

32

79.1

82

84.9

33

78.8

83

87.2

34

82.1

85.5

88.4

35

84

87.3

90.6

36

84.8

89

93.2

37

86.5

90.8

95.1

38

88.4

92.4

96.4

39

89

94

99

40

91.2

94.8

98.4

41

93.7

95.8

97.9

42

94.2

97.5

100.8