Table 1.

Common risks and physiologic changes during pregnancy categorized based on trimesters

Trimester	Physiologic Changes	Risk Factors
First	- Central nervous systemdevelopment- Increased white blood cell count- Increased erythrocyte sedimentation rate	-Radiosensitive developmentperiod-Increased risk of teratogenesis-Hypercoagulable state-Increased risk of abortion with general anesthesia
Second	- Relatively radio resistant fetal central nervous system- Increased white blood cell count- Increased erythrocyte sedimentation rate	-Increased risk of supineaortocaval compression-Hypercoagulable state-Increased risk of abortion with general anesthesia-Increased risk of seat belt-related injury to the fetus
Third	- Maternal blood volumeincreased by 40%–50%- Increased white blood cell count- Increased erythrocyte sedimentation rate	-Increased risk of supineaortocaval compression-Increased risk of pregnancy-related osteoporosis-Increased risk of seat belt-related injury to the fetus