From fertilisation
4 weeks 4mm
5 weeks 8mm
6 weeks 1.3cm
7 weeks 1.8cm

10 weeks 8 cm
14 weeks 15 cm
19 weeks 20 cm
21 weeks 28 cm
24 weeks 38 cm
29 weeks 43 cm
33 weeks 48 cm
38 weeks 53 cm
i.e. 40 weeks from last period