Abstract： Objective To investigate the risk factors associated with abnormal cervical cytology findings in pregnant women. Methods From Sep. 2007 to Sep. 2008, 12 112 pregnant women who underwent their antenatal examinations at 12-36 gostational weeks in Beijing Obsteties and Gynecology Hospital were enrolled in this study. They were all excluded from the following pathologic obstetrics factors including threatened abortion, premature rupture of membranes or placental previa Thinprep cytology test (TCT) were given at their first examination, meanwhile, a personal clinic file was established to record her occupation, education, address, family income, nationality, age of first intercourse, number of sex partners, contraception, marriage and pregnancy, current gynecologic diseases, family history of gynecologic tumors, history of gynecologic diseases and smoking and result of pelvic examination. Those risk factors leading to abnormal cervical cytology were analyzed. Results The complete clinical data were collected from 11 906 cases(98.30%, 11 906/12 112). It was found that 10 354 women were shown with normal TCT result, however, 1134 women (9.52%, 1134/11 906) with atypical squamaous cells of undetermined significance(ASCUS), 112 women (0.94%, 112/11 906) with atypical glandular cells of undetermined significance(AGUS), 229 women (1.92%, 229/11 906) with low grade squamaous intraepithelial(LSIL),74 women (0.62%, 74/11906) with high grade squamaous intraepithelial(HSIL). Multiple factorial non-conditioned logistic regression analysis showed that age of first sexual intercourse (OR_(ASCUS)=2.90, OR_(AGUS)=7. 32), number of sex partners (OR_(AGUS)=1.49, OR_(AGUS)=2. 02), number of abortion (OR_(ASCUS)=1.68,OR_(AGUS)=3.50) were correlated with ASCUS and AGUS. In LSIL group and HSIL group, age of first sexual intercourse (OR_(LSIL)=6. 34, OR_(HSIL)=9.26), number of sex partners (OR_(LSIL)=1.69, OR_(HSIL)=1.6.5),number of abortion (OR_(LSIL)=1.53, OR_(HSIL)=5. 33), smoking (OR_(LSIL)=1.84, OR_(HSIL)=1.77) were remarkable variables. The infection of human papilloma virus (HPV) and trichomonas vaginitis were correlated with abnormal cervical cytology(including ASCUS, AGUS, LSIL and HSIL) significantly (P< 0.01). Columnar epithelium dystopia were also significantly correlated with abnormal cervical cytology (χ~2=43. 269, P=0. 000). However, abnormal cervical cytology was uncorrelated with degrees of Columnar epithelium dystopia. Conclusions The risk factors associated with abnormal cervical cytology in pregnant women were the same with those of non-pregnant women.