A typical pregnancy lasts for about 40 weeks. However, this number may be vary based on the number of developing babies, as well as both baby’s and the mother’s health. These 40 weeks or so are divided up into three stages, or trimesters. Each trimester contains unique milestones for both mom and baby.
Identification of Pregnancy Stages
Pregnancy is divided into three trimesters, each of which lasts approximately three months. The first trimester lasts from week one, which is the first week of the last menstrual period, until week 12 or 14. Different resources vary on the definition of the first trimester. The American Pregnancy Association marks the end of the first trimester after week 13, while the U.S. Department of Health and Human Services reports that it ends after week 12. The second trimester lasts from the end of the first until around week 26 or 28, depending on which resource your doctor uses. The third and final trimester lasts from the end of the second until week 40, though for some women, pregnancy may carry on for an additional week or two after their due date.
Significant Milestones During Each Stage
Each trimester has its own unique milestones. During the first trimester, the baby grows from a tiny cluster of cells into something recognizably human. During the second trimester, the baby continues to grow and the mother’s belly becomes noticeably pregnant. Right at the end of the second trimester, according to the American Pregnancy Association, the baby could survive if born prematurely, though medical attention in a neonatal intensive care unit would be necessary. During the third trimester, the baby makes its final preparations for descent through the birth canal. By week 37, the baby is considered to be full-term.
Baby Changes in Each Stage
During the first trimester, the baby’s heart begins to beat. The organs, bones and muscles begin to form. By the end of this stage, the American Pregnancy Association reports that the baby can make a fist. During the second trimester, the baby begins to change from something slightly human-looking into something resembling a newborn baby, though the American Pregnancy Association reports that even at the end of this trimester, he will only weigh about 2 lbs. Perhaps the most exciting milestone during this trimester is quickening, when the mother can feel the baby’s movements. During the third trimester, the baby’s organs and lungs mature. He may begin to practice doing “baby things,” such as sucking his thumb and taking breaths of amniotic fluid. During this final stage of pregnancy, he puts on the pounds, reaching his birth weight.
Mom Changes in Each Stage
The first trimester is when the notorious “morning sickness” tends to occur. HHS also lists fatigue, food cravings and breast tenderness among the first trimester pregnancy symptoms. However, they report that for most women, many of these unpleasant pregnancy symptoms wear off by the second trimester. During the second trimester, the mother develops the linea alba, which is the dark line that runs down the belly, and may also have darkening of the face and nipple skin. Her hands and feet may also itch. Fatigue often returns in the third trimester, as the body prepares itself for birth. During this time, mom may experience swelling in the hands and feet, difficulty sleeping at night and Braxton-Hicks contractions, or false labor.
Labor: The Final Stage of Pregnancy
Dress rehearsal is over: it’s time for the show! As the delivery date draws near, lots of changes take place. HHS reports that the cervix begins to thin and dilate, and the baby drops toward the birth canal. Other signs that labor is about to begin include regular contractions, the water breaking as well as a pinkish discharge called the “bloody show.”
