Pregnancy Week by Week
(First, Second, and Third Trimester)
- Pregnancy facts*
- What is the first trimester (week 1-week 12)?
- What is the second trimester (week 13-week 28)?
- What is the third trimester (week 29-week 40)?
- How will my baby develop week by week?
- What are the changes that happen to a woman's body during her 1st, 2nd, and 3rd trimesters of pregnancy?
- Body aches
- Breast changes
- Fatigue, sleep problems
- Heartburn and indigestion
- Leg cramps
- Morning sickness
- Nasal problems
- Numb or tingling hands
- Stretch marks, skin changes
- Urinary frequency and leaking
- Varicose veins
- Stages of Pregnancy - Slideshow
- Pregnancy Myths and Facts FAQs
- Patient Comments: Pregnancy - Describe Your Experience
- Patient Comments: Pregnancy - Signs
- Find a local Obstetrician-Gynecologist in your town
*Pregnancy facts medical author: Melissa Conrad Stöppler, MD
- A normal pregnancy lasts about 40 weeks and is grouped into three
- Symptoms of early pregnancy include the absence of
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.
What is the first trimester (week 1-week 12)?
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
- 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.
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