Pregnancy (Stages, Trimesters) Body Changes and Baby Week by Week Development Information on MedicineNet.com

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Pregnancy Stages
(First, Second, and Third Trimester)

Stages of Pregnancy Slideshow

Pregnant or Not? How To Know

Medical Author: Medical Author: Melissa Stoppler, M.D.
Medical Editor: Barbara K. Hecht, Ph.D.

Pregnant or Not? 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.

All pregnancy tests are based upon measurement of the same hormone -- human chorionic gonadotrophin or hCG -- which is only present in a woman when she is pregnant. This hormone is made after the egg is fertilized and its levels rise rapidly in early pregnancy. It acts to support progesterone, a hormone necessary to maintain the pregnancy.

Most home pregnancy tests are done because of a missed period. If a woman has regular menstrual cycles, a home test can be very informative. It can tell whether or not there is a pregnancy as early as the first day of the missed period (which is about two weeks after conception).

Manufacturers of home test kits claim that their kits are 97%-99% accurate, but the sensitivities of different test kits depend on the levels of hCG in the urine required for a positive result. If your test result is positive, see your healthcare provider promptly.

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Introduction

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
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.