Objective To study the expression changes of placental insulin-like growth factor Ⅰ and Ⅱ (IGF-Ⅰ and IGF-Ⅰ) between pregnancies following the in vitro fertilization and embryo transfer (IVF-ET) and those conceived spontaneously.Methods The placenta were collected from 49 cases of pregnancies after IVF-ET(case group) and 49 cases of pregnancies who were normal (control group).The expressions of IGF-Ⅰ and IGF-Ⅱ mRNA in placenta were detected by reverse transcription-polymeras chain reaction (RT-PCR).The levels of IGF-Ⅰ and IGF-Ⅱ protein were determined by immunohistochemistry.Results The mRNA levels of the placental IGF-Ⅰ and IGF Ⅱ were 0.30 ±0.13 and 0.28 ±0.04 in the IVF-ET group,and 0.65 ±0.10 and 0.91 ±0.26 in the control group.The protein levels of the placental IGF-Ⅰ and IGF-Ⅱ were 0.26 ±0.04 and 0.29 ± 0.05 in the IVF-ET group,and 0.32 ± 0.07 and 0.34 ± 0.04 in the control group.The mRNA and protein expressions of IGF-Ⅰ and IGF-Ⅱ in human placenta were significantly decreased in IVF-ET group compared to control group (P ＜ 0.05).The incidence rate of low birth weight infant in IVF-ET group was significantly higher than control(P ＞ 0.05).Conclusions Expressions of placental IGF-Ⅰ and IGF-Ⅱ in the IVF-ET group did not affect fetal growth and development.