What Is Pregnancy

Pregnancy is a nine-month period in which a child develops from the fertilization of a woman's egg after intercourse. Pregnancy technically begins two weeks before a woman can detect it with home or clinical tests.

Pregnancy is split into three periods of development called trimesters, which can help a woman better understand what she can expect during the next 40 weeks. The first trimester, weeks one through 12, is a time when the fetus is developing from a zygote and embryo. The woman's body is also experiencing hormonal changes in preparation for the next 38 weeks of supporting the pregnancy that she'll experience mood swings, nausea, tender and swollen breasts and other physical discomforts that usually fade by the second trimester.

The second trimester, weeks 13 to 27, is a time in which the baby's sex can be determined and he or she begins to move around in the uterus.

During the third trimester, weeks 28 to 40, the baby opens its eyes, practices breathing, rapidly gains weight and prepares to come into the world.

The baby's development is the key to pregnancy but requires more than a warm body. A pregnancy is a period of time when a woman needs to abstain from drugs and alcohol, increase her intake of certain nutrients to help the baby grow and needs to engage in some form of prenatal care to ensure the baby will be healthy when the post-pregnancy stage of becoming a parent and raising the infant into adulthood begins.