The purpose of this qualitative study was to explore the monitoring and maintaining behaviors in the first trimester of pregnancy in women who received assisted reproduction and became pregnant for the first time. Clinical field method was employed in this study. Data was collected for two months from the fourth week of the pregnancy to the twelfth week. The recorded verbal behaviors were systemically analysed and categorized using content analysis approach. The findings revealed that there was a total of 2,931 behavior units in both monitoring and maintaining behaviors derived from the data. Monitoring behaviors occupied 85.2% of the total behavior units, and were divided into sensing behaviors and proving behaviors. Maintaining behavior accounted for 14.8% of the total behavior units, and included avoiding, approaching and rationalization behaviors. Monitoring and maintaining behaviors which were related to pregnancy experience accounted for 67.8%, while fetal grow accounted for 21.1%, fetus’s medical management 6.1% and mother’s medical management 5%. With respect to pregnancy experience, after these women were told that they were pregnant, they turned to involvement in monitoring their physical changes to be sure of their pregnancy and safe guarding their health. In respect to fetal growth, these women turned to paying special attention to their fetuses and the condition of their fetuses. In respect to the fetal management and multiple pregnancy concern, these women expressed their worries of the risk of losing their only selected fetus and that the healthy male fetus would be mistakenly removed during the process of fetus reduction. Regarding mothers medical management, both women with single pregnancy and multiple pregnancy expressed their strong concerns that delivery should be carefully arranged.