Breast Tenderness

• Breast tenderness and swelling is an early sign of pregnancy that occurs due to hormonal changes within the first one to two weeks after conception. The HCG injection may also cause this side effect.
  
  

Headache

• In early pregnancy, headaches can occur because of a rapid increase in hormones. Headaches are also found to be a side effect of the HCG injection.
  
  

Nausea

• Nausea is a part of early pregnancy for some women due to quickly rising levels of estrogen. The HCG injection could also cause symptoms of nausea as a side effect.
  
  

Mood Swings

• Changes in mood can be found within early pregnancy as a woman's body produces large amounts of hormones. HCG injections also can cause a woman to experience irritability and altered mood.
  
  

Considerations

• The hormone HCG that is contained within the fertility medication is the same hormone that is produced in early pregnancy. Effects from the HCG injection wear off in 7 to 14 days from the last injection, at which point the symptoms and HCG found in your blood would be indicative of a pregnancy.