Nausea

• You may experience nausea just days into a pregnancy because the body begins producing progesterone immediately.
  
  

Breast Changes

• Your breasts may become swollen and sore before a missed period due to the hormonal changes of pregnancy.
  
  

Emotional Changes

• Mood swings may set in before you miss a period. Fluctuating hormones cause pregnancy symptoms similar to pre-menstrual syndrome.
  
  

Fatigue

• A common symptom of pregnancy before a missed period is fatigue. Progesterone makes pregnant women feel tired, along with lowered blood pressure and blood sugar level changes.
  
  

Digestive Symptoms

• Constipation and heartburn are common pregnancy symptoms in the weeks before a period is missed. Pregnancy slows the digestive tract, which results in sluggish movement of food and waste products.