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

Pregnant or Not?

Pregnant or Not? How To Know

To learn whether you are pregnant or not, a pregnancy test may provide you with the answer. This test can be done in the privacy of your home using one of several available test kits. Or the test can be performed in your doctor?s office or clinic. Home pregnancy tests are always done on urine while those in a doctor?s office or clinic may be done on urine or blood.

Quick GuideStages of Pregnancy: 1st, 2nd, 3rd Trimester Images

Stages of Pregnancy: 1st, 2nd, 3rd Trimester Images

Pregnancy definition and facts*

*Pregnancy facts medical author: Melissa Conrad Stöppler, MD

  • A normal pregnancy lasts about 40 weeks and is grouped into three stages, or trimesters.
  • Symptoms and early signs of pregnancy include
  • the absence of menstrual periods,
  • A pregnancy test measures the level of hormone human chorionic gonadotropin (HCG) in the urine or blood. The test may be positive before the first signs of pregnancy develop in some women.
  • Symptoms of late pregnancy can include
    • heartburn,
    • difficulty sleeping,
    • swelling of the ankles or fingers,
    • hemorrhoids, and
    • mild contractions.
  • Many of these symptoms result from the weight gain and enlarging uterus in late pregnancy.
  • 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.

How many weeks is a normal term pregnancy?

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 of pregnancy (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
  • 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.

Medically Reviewed by a Doctor on 10/6/2016

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