Abstract： Objective To identify the genetic mechanism of fetuses with short limbs deformity.Methods From Aug.2008 to Aug.2011,ten fetuses with obvious short limbs were found in ultrasound screening performed at 18-24 and (or) 30-32 gestational weeks and underwent artificial induced labor with the patient' consent.Amniotic fluid or cord blood of the fetuses was collected for karyotyping analysis and detection of mutation point of fibroblast growth factor receptor 3 (FGFR3)gene by polymerase chain reaction and gene sequencing.One fetus (case 3) who presented with achondrogenesis underwent sequencing of SLC26A2 and Trip11 gene meanwhile.Results Among the 10 fetuses with short limbs deformity,five cases were found during second trimester and five during third trimester.Nine cases were identified as normal karyotype and one was chimera (46,XY/45,XY,- 18).One fetus carried a rare FGFR3 mutation of c.1108G＞T (G370C) and was diagnosed as thanatophoric dysplasia at 21+3 weeks.Three fetus carried c.1138G＞A (G380R) mutation and were diagnosed as achondroplasia.These four families had low recurrent risk because no gene mutations were found in the parents.Three mothers of these four fetuses were pregnant again and had normal neonates now.No mutations were found in all gene sequencing in case 3.Conclusions Karyotyping analysis and sequencing of FGFR3 gene could find causative gene mutations and provide genetic counselling and prenatal diagnosis for some fetuses with short limbs deformity.In the third trimester,achondroplasia is the most possible diagnosis when short limbs fetus is found by ultrasound.