Time from conception Weight in metric Size in metric Weight in pounds Size in inches
2 weeks 0.1 to 0.2 mm
3 weeks 0.2 to 0.5 mm 0.01
4 weeks 4 to 5 mm 0.16
5 weeks 5 to 7 mm 0.20
6 weeks 1.5 g 9 to 14 mm 0.39
7 weeks 2 g 17 to 22 mm 0.79
8 weeks 3 g 3.0 cm 0.01 1.18
9 weeks 10 g 5.5 cm 0.02 2.17
10 weeks 20 g 7.5 cm 0.04 2.95
11 weeks 30 g 8.5 cm 0.07 3.35
12 weeks 45 g 10.0 cm 0.10 3.94
13 weeks 65 g 12.0 cm 0.14 4.72
14 weeks 110 g 14.0 cm 0.24 5.51
15 weeks 135 g 16.0 cm 0.30 6.30
16 weeks 160 g 17.5 cm 0.35 6.89
17 weeks 200 g 19.0 cm 0.44 7.48
18 weeks 250 g 20.0 cm 0.55 7.87
19 weeks 270 g 21.0 cm 0.59 8.27
20 weeks 380 g 22.5 cm 0.84 8.86
21 weeks 450 g 24.0 cm 0.99 9.45
22 weeks 500 g 26.0 cm 1.10 10.24
23 weeks 550 g 28.0 cm 1.21 11.02
24 weeks 650 g 30.0 cm 1.43 11.81
25 weeks 750 g 32.0 cm 1.65 12.60
26 weeks 850 g 33.0 cm 1.87 12.99
27 weeks 1000 g 34.0 cm 2.20 13.39
28 weeks 1150 g 35.0 cm 2.53 13.78
29 weeks 1300 g 36.0 cm 2.86 14.17
30 weeks 1500 g 37.0 cm 3.30 14.57
31 weeks 1700 g 39.0 cm 3.74 15.35
32 weeks 1900 g 40.5 cm 4.18 15.94
33 weeks 2100 g 42.0 cm 4.62 16.54
34 weeks 2300 g 43.0 cm 5.06 16.93
35 weeks 2500 g 45.0 cm 5.50 17.72
36 weeks 2700 g 46.5 cm 5.94 18.31
37 weeks 2900 g 48.0 cm 6.38 18.90
38 weeks 3000 g 50.0 cm 6.60 19.69