AC, abdominal circumference; BPD, biparietal diameter; FL, femur length; HC, head circumference; ND, no data.
* Data from Hadlock FP, Harrist RB, Martinez-Poyer J: How accurate is second trimester fetal dating? J Ultrasound Med 10:557, 1992.
† Data from Rossavik IK, Fishburne JI: Conceptional age, menstrual age, and ultrasound age: a second trimester comparison of pregnancies of known conception date with pregnancies dated from the last menstrual period. Obstet Gynecol 73:243, 1989.
‡ Data from Persson PH, Weldner BM: Reliability of ultrasound fetometry in estimating gestational age in the second trimester. Acta Obstet Gynecol Scand 65:481, 1986.
§ Data from Benson CB, Doubilet PM: Sonographic prediction of gestational age: accuracy of second and third trimester fetal measurements. Am J Roentgenol 157:1275, 1991.
TABLE A-5
Variability in Predicting Menstrual Age in the Second Half of Pregnancy (14-42 Weeks)
Adapted from Benson CB, Doubilet PM: Sonographic prediction of gestational age: accuracy of second and third trimester fetal measurements. Am J Roentgenol 157:1275, 1991.
* Data from Jeanty P, Cantraine F, Cousaert E, et al: The binocular distance: a new way to estimate fetal age. J Ultrasound Med 3:241, 1984.
† Data from Hill LM: Transverse cerebellar diameter as a predictor of menstrual age. Obstet Gynecol 75:983, 1990.
‡ Data from Yarkoni S, Schmidt W, Jeanty P, et al: Clavicular measurement: a new biometric parameter for fetal evaluation. J Ultrasound Med 4:467, 1985.
§ Data from Hill LM, Guzick D, Thomas ML, et al: Fetal radius length: a critical evaluation of race as a factor in gestational age assessment. Am J Obstet Gynecol 161:193, 1989.
|| Data from Jeanty P, Rodesch F, Delbeke D: Estimation of fetal age by long bone measurements. J Ultrasound Med 3:75, 1984.
¶ Data from Mercer BM, Sklar S, Shariatmadar A, et al: Fetal foot length as a predictor of gestational age. Am J Obstet Gynecol 15:350, 1987.
TABLE A-7
Gestational Sac Measurement
From Hellman LM, Kobayashi M, Fillisti L, et al: Growth and development of the human fetus prior to the twentieth week of gestation. Am J Obstet Gynecol 103:789, 1969.
Mean Predicted Gestational Sac (cm)
Gestational Age (wk)
Mean Predicted Gestational Sac (cm)
Gestational Age (wk)
1.0
5.0
3.6
8.8
1.1
5.2
3.7
8.9
1.2
5.3
3.8
9.0
1.3
5.5
3.9
9.2
1.4
5.6
4.0
9.3
1.5
5.8
4.1
9.5
1.6
5.9
4.2
9.6
1.7
6.0
4.3
9.7
1.8
6.2
4.4
9.9
1.9
6.3
4.5
10.0
2.0
6.5
4.6
10.2
2.1
6.6
4.7
10.3
2.2
6.8
4.8
10.5
2.3
6.9
4.9
10.6
2.4
7.0
5.0
10.7
2.5
7.2
5.1
10.9
2.6
7.3
5.2
11.0
2.7
7.5
5.3
11.2
2.8
7.6
5.4
11.3
2.9
7.8
5.5
11.5
3.0
7.9
5.6
11.6
3.1
8.0
5.7
11.7
3.2
8.2
5.8
11.9
3.3
8.3
5.9
12.0
3.4
8.5
6.0
12.2
3.5
8.6
TABLE A-8
Combined Data Comparing Menstrual Age With Mean Gestational Sac Diameter, Crown-Rump Length, and hCG Levels *
Menstrual Age (days)
Menstrual Age (wk)
Gestational Sac Size (mm)
Crown-Rump Length (cm)
HCG LEVEL (FIRST IRP)
Mean (U/L)
Range (U/L)
30
4.3
31
4.4
32
4.6
3
1710
(1050-2800)
33
4.7
4
2320
(1440-3760)
34
4.9
5
3100
(1940-4980)
35
5.0
5.5
4090
(2580-6530)
36
5.1
6
5340
(3400-8450)
37
5.3
7
6880
(4420-10,810)
38
5.4
8
8770
(5680-13,660)
39
5.6
9
11,040
(7220-17,050)
40
5.7
10
0.2
13,730
(9050-21,040)
41
5.9
11
0.3
15,300
(10,140-23,340)
42
6.0
12
0.35
16,870
(11,230-25,640)
43
6.1
13
0.4
20,480
(13,750-30,880)
44
6.3
14
0.5
24,560
(16,650-36,750)
45
6.4
15
0.6
29,110
(19,910-43,220)
46
6.6
16
0.7
34,100
(25,530-50,210)
47
6.7
17
0.8
39,460
(27,470-57,640)
48
6.9
18
0.9
45,120
(31,700-65,380)
49
7.0
19
0.95
50,970
(36,130-73,280)
50
7.1
20
1.0
56,900
(40,700-81,150)
51
7.3
21
1.1
62,760
(45,300-88,790)
52
7.4
22
1.2
68,390
(49,810-95,990)
53
7.6
23
1.3
73,640
(54,120-102,540)
54
7.7
24
1.4
78,350
(58,100-108,230)
55
7.9
25
1.5
82,370
(61,640-112,870)
56
8.0
26
1.6
85,560
(64,600-116,310)
57
8.1
26.5
1.7
58
8.3
27
1.8
59
8.4
28
1.9
60
8.6
29
2.0
61
8.7
30
2.1
62
8.9
31
2.2
63
9.0
32
2.3
64
9.1
33
2.4
65
9.3
34
2.5
66
9.4
35
2.6
67
9.6
36
2.8
68
9.7
37
2.9
69
9.9
38
3.0
70
10.0
39
3.1
71
10.1
40
3.2
72
10.3
41
3.4
73
10.4
42
3.5
74
10.6
43
3.7
75
10.7
44
3.8
76
10.9
45
4.0
77
11.0
46
4.1
78
11.1
47
4.2
79
11.3
48
4.4
80
11.4
49
4.6
81
11.6
50
4.8
82
11.7
51
5.0
83
11.9
52
5.2
84
12.0
53
5.4
hCG, human chorionic gonadotropin; IRP, International Reference Preparation; U/L, units/liter.
Table appears in this form in Nyberg DA, Hill LM, Bohm-Velez M, et al: Transvaginal Ultrasound. St. Louis, Mosby-Year Book, 1992.
* Data from Daya S, Woods S: Transvaginal ultrasound scanning in early pregnancy and correlation with human chorionic gonadotropin levels. J Clin Ultrasound 19:139, 1991; Hadlock FP, Shah YP, Kanon DJ, et al: Fetal crown rump length: reevaluation of relation to menstrual age (5-18 weeks) with high-resolution real-time US. Radiology 182:501, 1992; and Robinson HP: “Gestation sac” volumes as determined by sonar in the first trimester of pregnancy. Br J Obstet Gynaecol 82:100, 1975.
TABLE A-9
Predicted Menstrual Age (MA) in Weeks From Crown-Rump Length (CRL) Measurements (cm) *
From Hadlock FP, Shah YP, Kanon DJ, et al: Fetal crown-rump length: reevaluation of relation to menstrual age (5-18 weeks) with high-resolution real-time US. Radiology 182:501, 1992.
CRL
MA
CRL
MA
CRL
MA
0.2
5.7
4.2
11.1
8.2
14.2
0.3
5.9
4.3
11.2
8.3
14.2
0.4
6.1
4.4
11.2
8.4
14.3
0.5
6.2
4.5
11.3
8.5
14.4
0.6
6.4
4.6
11.4
8.6
14.5
0.7
6.6
4.7
11.5
8.7
14.6
0.8
6.7
4.8
11.6
8.8
14.7
0.9
6.9
4.9
11.7
8.9
14.8
1.0
7.2
5.0
11.7
9.0
14.9
1.1
7.2
5.1
11.8
9.1
15.0
1.2
7.4
5.2
11.9
9.2
15.1
1.3
7.5
5.3
12.0
9.3
15.2
1.4
7.7
5.4
12.0
9.4
15.3
1.5
7.9
5.5
12.1
9.5
15.3
1.6
8.0
5.6
12.2
9.6
15.4
1.7
8.1
5.7
12.3
9.7
15.5
1.8
8.3
5.8
12.3
9.8
15.6
1.9
8.4
5.9
12.4
9.9
15.7
2.0
8.6
6.0
12.5
10.0
15.9
2.1
8.7
6.1
12.6
10.1
16.0
2.2
8.9
6.2
12.6
10.2
16.1
2.3
9.0
6.3
12.7
10.3
16.2
2.4
9.1
6.4
12.8
10.4
16.3
2.5
9.2
6.5
12.8
10.5
16.4
2.6
9.4
6.6
12.9
10.6
16.5
2.7
9.5
6.7
13.0
10.7
16.6
2.8
9.6
6.8
13.1
10.8
16.7
2.9
9.7
6.9
13.1
10.9
16.8
3.0
9.9
7.0
13.2
11.0
16.9
3.1
10.0
7.1
13.3
11.1
17.0
3.2
10.1
7.2
13.4
11.2
17.1
3.3
10.2
7.3
13.4
11.3
17.2
3.4
10.3
7.4
13.5
11.4
17.3
3.5
10.4
7.5
13.6
11.5
17.4
3.6
10.5
7.6
13.7
11.6
17.5
3.7
10.6
7.7
13.8
11.7
17.6
3.8
10.7
7.8
13.8
11.8
17.7
3.9
10.8
7.9
13.9
11.9
17.8
4.0
10.9
8.0
14.0
12.0
17.9
4.1
11.0
8.1
14.1
12.1
18.0
* The 95% confidence interval is ±8% of the predicted age.
TABLE A-11
Predicted Menstrual Age for Head Circumference Measurements (8.5-36.0 cm)
From Hadlock FP, Deter RL, Harrist RB, et al: Fetal head circumference: relation to menstrual age. AJR Am J Roentgenol 138:649, 1982.
Head Circumference (cm)
Menstrual Age (wk)
Head Circumference (cm)
Menstrual Age (wk)
8.5
13.7
22.5
24.4
9.0
14.0
23.0
24.9
9.5
14.3
23.5
25.4
10.0
14.6
24.0
25.9
10.5
15.0
24.5
26.4
11.0
15.3
25.0
26.9
11.5
15.6
25.5
27.5
12.0
15.9
26.0
28.0
12.5
16.3
26.5
28.6
13.0
16.6
27.0
29.2
13.5
17.0
27.5
29.8
14.0
17.3
28.0
30.3
14.5
17.7
28.5
31.0
15.0
18.1
29.0
31.6
15.5
18.4
29.5
32.2
16.0
18.8
30.0
32.8
16.5
19.2
30.5
33.5
17.0
19.6
31.0
34.2
17.5
20.0
31.5
34.9
18.0
20.4
32.0
35.5
18.5
20.8
32.5
36.3
19.0
21.2
33.0
37.0
19.5
21.6
33.5
37.7
20.0
22.1
34.0
38.5
20.5
22.5
34.5
39.2
21.0
23.0
35.0
40.0
21.5
23.4
35.5
40.8
22.0
23.9
36.0
41.6
VARIABILITY ESTIMATES (±2 SD)
12-18 wk
±1.3 wk
18-24 wk
±1.6 wk
24-30 wk
±2.3 wk
30-36 wk
±2.7 wk
36-42 wk
±3.4 wk
TABLE A-12
Percentile Values for Fetal Head Circumference
Adapted from Hadlock FP, Deter RL, Harrist RB, et al: Estimating fetal age: computer-assisted analysis of multiple fetal growth parameters. Radiology 152:497, 1984.
Menstrual Weeks
HEAD CIRCUMFERENCE (CM) BY PERCENTILE
3rd
10th
50th
90th
97th
14
8.8
9.1
9.7
10.3
10.6
15
10.0
10.4
11.0
11.6
12.0
16
11.3
11.7
12.4
13.1
13.5
17
12.6
13.0
13.8
14.6
15.0
18
13.7
14.2
15.1
16.0
16.5
19
14.9
15.5
16.4
17.4
17.9
20
16.1
16.7
17.7
18.7
19.3
21
17.2
17.8
18.9
20.0
20.6
22
18.3
18.9
20.1
21.3
21.9
23
19.4
20.1
21.3
22.5
23.2
24
20.4
21.1
22.4
23.7
24.3
25
21.4
22.2
23.5
24.9
25.6
26
22.4
23.2
24.6
26.0
26.8
27
23.3
24.1
25.6
27.1
27.9
28
24.2
25.1
26.6
28.1
29.0
29
25.0
25.9
27.5
29.1
30.0
30
25.8
26.8
28.4
30.0
31.0
31
26.7
27.6
29.3
31.0
31.9
32
27.4
28.4
30.1
31.8
32.8
33
28.0
29.0
30.8
32.6
33.6
34
28.7
29.7
31.5
33.3
34.3
35
29.3
30.4
32.2
34.1
35.1
36
29.9
30.9
32.8
34.7
35.8
37
30.3
31.4
33.3
35.2
36.3
38
30.8
31.9
33.8
35.8
36.8
39
31.1
32.2
34.2
36.2
37.3
40
31.5
32.6
34.6
36.6
37.7
TABLE A-13
Predicted Menstrual Age for Abdominal Circumference Measurements (10-36 cm)
From Hadlock FP, Deter RL, Harrist RB, et al: Fetal abdominal circumference as a predictor of menstrual age. AJR Am J Roentgenol 139:367, 1982.
Abdominal Circumference (cm)
Menstrual Age (wk)
Abdominal Circumference (cm)
Menstrual Age (wk)
10.0
15.6
23.5
27.7
10.5
16.1
24.0
28.2
11.0
16.5
24.5
28.7
11.5
16.9
25.0
29.2
12.0
17.3
25.5
29.7
12.5
17.8
26.0
30.1
13.0
18.2
26.5
30.6
13.5
18.6
27.0
31.1
14.0
19.1
27.5
31.6
14.5
19.5
28.0
32.1
15.0
20.0
28.5
32.6
15.5
20.4
29.0
33.1
16.0
20.8
29.5
33.6
16.5
21.3
30.0
34.1
17.0
21.7
30.5
34.6
17.5
22.2
31.0
35.1
18.0
22.6
31.5
35.6
18.5
23.1
32.0
36.1
19.0
23.6
32.5
36.6
19.5
24.0
33.0
37.1
20.0
24.5
33.5
37.6
20.5
24.9
34.0
38.1
21.0
25.4
34.5
38.7
21.5
25.9
35.0
39.2
22.0
26.3
35.5
39.7
22.5
26.8
36.0
40.2
23.0
27.3
VARIABILITY ESTIMATES (±2 SD)
12-18 wk
±1.9 wk
18-24 wk
±2.0 wk
24-30 wk
±2.2 wk
30-36 wk
±3.0 wk
36-42 wk
±2.5 wk
TABLE A-14
Percentile Values for Fetal Abdominal Circumference
Adapted from Hadlock FP, Deter RL, Harrist RB, et al: Estimating fetal age: computer-assisted analysis of multiple fetal growth parameters. Radiology 152:497, 1984.
Menstrual Age (Wks)
ABDOMINAL CIRCUMFERENCE (CM) BY PERCENTILE
3rd
10th
50th
90th
97th
14
6.4
6.7
7.3
7.9
8.3
15
7.5
7.9
8.6
9.3
9.7
16
8.6
9.1
9.9
10.7
11.2
17
9.7
10.3
11.2
12.1
12.7
18
10.9
11.5
12.5
13.5
14.1
19
11.9
12.6
13.7
14.8
15.5
20
13.1
13.8
15.0
16.3
17.0
21
14.1
14.9
16.2
17.6
18.3
22
15.1
16.0
17.4
18.8
19.7
23
16.1
17.0
18.5
20.0
20.9
24
17.1
18.1
19.7
21.3
22.3
25
18.1
19.1
20.8
22.5
23.5
26
19.1
20.1
21.9
23.7
24.8
27
20.0
21.1
23.0
24.9
26.0
28
20.9
22.0
24.0
26.0
27.1
29
21.8
23.0
25.1
27.2
28.4
30
22.7
23.9
26.1
28.3
29.5
31
23.6
24.9
27.1
29.4
30.6
32
24.5
25.8
28.1
30.4
31.8
33
25.3
26.7
29.1
31.5
32.9
34
26.1
27.5
30.0
32.5
33.9
35
26.9
28.3
30.9
33.5
34.9
36
27.7
29.2
31.8
34.4
35.9
37
28.5
30.0
32.7
35.4
37.0
38
29.2
30.8
33.6
36.4
38.0
39
29.9
31.6
34.4
37.3
38.9
40
30.7
32.4
35.3
38.2
39.9
TABLE A-15
A Comparison of Abdominal Circumference Percentiles Using Sonography