Pregnancy Week by Week
(First, Second, and Third Trimester)

1. Stages of Pregnancy Slideshow Pictures
2. Early Pregnancy Symptoms Slideshow Pictures
3. Conception (Egg to Embryo) Slideshow Pictures

*Pregnancy facts medical author: Melissa Conrad Stöppler, MD

• A normal pregnancy lasts about 40 weeks and is grouped into three trimesters.
  
  
• Symptoms of early pregnancy include the absence of menstrual periods, breast changes, tiredness, nausea, mood swings, or other symptoms.
  
  
• A pregnancy test measures the hormone human chorionic gonadotropin in the urine or blood.
  
  
• Symptoms of late pregnancy can include heartburn, difficulty sleeping, swelling of the ankles or fingers, hemorrhoids, and mild contractions.
  
  
• By the end of 37 weeks, a baby is considered full term and its organs are ready to function on their own.
  
  
• As you near your due date, your baby may turn into a head-down position for birth. Most babies "present" head down.
  
  
• Babies at birth typically weigh between 6 pounds 2 ounces and 9 pounds 2 ounces and are 19 to 21 inches long. Most full-term babies fall within these ranges.

Pregnancy lasts about 40 weeks, counting from the first day of your last normal period. The weeks are grouped into three trimesters (TREYE-mess-turs). Find out what's happening with you and your baby in these three stages.

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.