12周龄:胎儿长到4.58厘米,外生殖器初步发育,如有畸形可表现,头颅钙化较为完善。头颅环状清晰,可测双顶径,畸形明显可诊断,此后各器官功能趋于完善。13周长:双顶径2.52士0.25腹围6.90士l.65股骨长1.17士0.3114周长:双顶径2.83士0.57腹围7.77士1.82股骨长1.38士0.48.15周长:双顶径3.23士0.51腹围9.13士1.56股骨长度1.74士0.58。16周长:双顶径3.62士0.58腹围10.32士1.92股骨长度2.10士0.51.17周长:双顶径3.97士0.44腹围11.49士1.62股骨长度2.52士0.44.18周长:双顶径4.25士0.53腹围12.41士l.89股骨长度2.71士0.46.19周长:双顶径4.52士0.53腹围13.59士2.30股骨长3.03士0.50.20周长:双顶径4.88士0.58腹围14.80士l.89股骨长3.35士O.47.21周长:双顶径5.22士0.42腹围15.62士1.84股骨长度3.64士0.40.22周长:双顶径5.45士0.57腹围16.70士2.23股骨长3.82士0.47.23周长:双顶径5.80士0.44腹围17.90士1.85士,骨长度4.21士0.41。24周长:双顶径6.05士0.50腹围18.74士2.23股骨长4.36士0.51.25周长:双顶径6.39士0.70腹围19.64士2.20股骨长4.65士0.42.26周长:双顶径6.68士0.61腹围21.62士2.30股骨长度4.87士O.41.27周长:双顶径6.98士0.57腹围21.81士2.12股骨长度5.10士0.41。28周长:双顶径7.24士O.65腹围22.86士2.41股骨长5.35士0.55.29周长:双顶径7.50士0.65腹围:23.71士1.50股骨长5.61士0.44.30周长:双顶径7.83士0.62腹围:24.88士2.03股骨长5.77士0.47.31周长:双顶径8.06士0.60腹围:25.78士2.32股骨长6.03士0.38。32周长:双顶径8.17士0.65腹围:26.20士2.33股骨长6.43士0.49.33周长:双顶径8.50士0.47腹围:27.78:士2.30股骨长6.52士0.46.34周长:双顶径8.61士0.63腹围:27.99士2.55骨长度6.62士0.43.35周长:双顶径8.70士0.55腹围:28.74士2.88股骨长6.71士0.45.36周长:双顶径8.81士0.57腹围:29.44士2.83股骨长6.95士0.47.37周长:双顶径9.00士0.63腹围:30.14士2017股骨长7.10士0.52.38周长:双顶径9.08士0.59腹围:30.63士2.83股骨长7.20士0.43.39周长:双顶径9.21士0.59腹围:31.34士3.12股骨长7.34士0.53.40周长:双顶径9.28士0.50腹围:31.49士2.79股骨长度7.4士0.53.