During the first trimester, your body undergoes many changes. Hormonal changes affect almost every organ system in your body. These changes can trigger symptoms even in the very first weeks of pregnancy. Your period stopping is a clear sign that you are pregnant. Other changes may include: 
•    Extreme tiredness 
•    Tender, swollen breasts. Your nipples might also stick out. 
•    Upset stomach with or without throwing up (morning sickness) 
•    Cravings or distaste for certain foods 
•    Mood swings 
•    Constipation (trouble having bowel movements) 
•    Need to pass urine more often 
•    Headache 
•    Heartburn 
•    Weight gain or loss 

As your body changes, you might need to make changes to your daily routine, such as going to bed earlier or eating frequent, small meals. Fortunately, most of these discomforts will go away as your pregnancy progresses. And some women might not feel any discomfort at all! If you have been pregnant before, you might feel differently this time around. Just as each woman is different, so is each pregnancy.