Pregnancy Baby Growth Chart. If there are concerns about your baby's growth in the third trimester of pregnancy, you may get scans to track size on a growth chart. Follow that curve until the end, where the percentiles are written on a white, shaded background.
The cartilage in the embryo begins to be replaced by bone. Find your baby’s length (in inches or centimetres) on the left side of the grid, and find your child’s age in months at the bottom of the chart. By 40 weeks, the average baby weighs 3.5kg (7.6lb), and is about 51.2cm (20.2in) long from head to heel.
