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Реферат: Stages Of Child Development Essay Research Paper
Stages Of Child Development Essay, Research Paper
Stages of Development
Pregnancy typically lasts 40 weeks, counting from the first day of the woman’s last menstrual period, and is often referred to in three parts, called trimesters. The first trimester lasts 12 weeks, the second is from 13 to 27 weeks, and the third is from 28 to 40 weeks. These divisions, however, are rough estimates, and you may encounter slightly different versions of these time periods. Your doctor will probably refer to your pregnancy by the age of the fetus in weeks. Certain important milestones in pregnancy occur during each trimester. For example, specific tests are done during the first trimester, and certain problems, if they develop, almost always arise during the third trimester. Although there is nothing crucial about these trimester divisions, they do help both the mother and the doctor in planning the management of the pregnancy.
THE FIRST TRIMESTER
The first trimester is a time of profound changes inside the woman?s body, and she will experience these changes in her own individual way. The first trimester may bring increased energy and a sense of well being; yet other women feel increasingly tired and emotional. But some others don’t notice many changes until much later in their pregnancy. The mother will experience these changes in her own individual way.
During the first trimester all of the baby’s essential structures and organ systems are formed during the first trimester. Those features will be continuing to grow and develop during the rest of the fetus’s time in the uterus. By the end of the first trimester, the average fetus is about 2 1/2 to 3 inches long and weighs about an ounce. Several organs and organ systems have formed and are beginning to function. The heart has been beating since about day 26. Reproductive organs have formed, although they cannot be seen well enough to determine the fetus’s sex. The first bone cells are forming. Fingers and toes are present, along with the beginnings of nails. The circulatory and respiratory systems are working. The liver is making bile, and the kidneys are secreting urine into the bladder. The fetus also begins to move during the first trimester, although it’s unlikely that the mother would feel any movement until later in pregnancy.
Although the physical changes of early pregnancy may make her uncomfortable, they don’t endanger the mother?s health or the health of the baby. Each pregnancy, of course, is unique, and she may experience many, some, or none of the changes and symptoms that usually occur. If this is not her first pregnancy, she might notice some changes are occurring earlier. This is sometimes referred to as the “warming up? effect. Some common side effects of the first trimester are fatigue, nausea and vomiting, urinary frequency, breast tenderness, headaches, dizziness, and weight gain.
THE SECOND TRIMESTER
By 26 weeks, the baby has grown to about 9 inches long and weighs about 1 1/2 pounds. Fat is being laid down under the red, wrinkled skin, which is covered with fine, downy hair called lanugo. Fingerprints and toe prints, as well as eyebrows and eyelashes have formed. By 28 weeks, the baby’s eyes open and close, and the baby sleeps and wakes at regular intervals. By that time, the baby will be about 10 inches long and will weigh about 2 pounds. The mother will probably have begun to feel the baby’s movements by 20 weeks. It is normal during this trimester for these movements to be somewhat erratic; later, they typically become more regular. The most active time is between 27 and 32 weeks.
As the baby’s activity increases, the pregnancy will begin to seem much more “real” to the mother. In the first trimester, she may have been constantly reminded of being pregnant because of nausea or other symptoms. But now the reminder begins to take the much more pleasant and exciting form of feeling your baby move. As time goes on, others will be able to feel movements through your abdomen.
About the time the mother begins to feel the baby move, the baby in turn is beginning to be able to hear you. Hearing is well established by 24 weeks, when the baby begins to respond to outside sounds. The baby can now hear the mother?s voice and is likely to recognize it after birth. The environment inside the uterus is relatively quiet, but the baby can hear the mother?s heart thumping, her blood whooshing through her veins and arteries, and the rumblings of her stomach. The rest of the baby’s sense organs also continue to develop during the second trimester. Beginning at 16 weeks the baby is sensitive to light, and by 29 weeks a baby can open his or her eyes and turn the head.
THE THRID TRIMESTER
The fetus continues to grow and put on weight throughout the last trimester of pregnancy. By the end of the 28th week, it weighs about 2 1/2 to 3 pounds and measures about 14 to 16 inches long. Because little fat has yet been laid down, the skin appears thin, red, and wrinkled. A slick, white, fatty substance called vernix caseosa covers the skin. The eyes open and close and the fetus may suck his or her thumb. The fetus continues to put on weight steadily, about half a pound each week until about 37 weeks. As the pregnancy reaches term, the baby begins to gain weight more slowly. As fat is laid down, the body becomes rounder. By the ninth month, the baby usually settles into a position for delivery, with the head down and arms and legs pulled up tightly against the chest. At 40 weeks, the average baby weighs about 7 to 7 1/2 pounds and measures about 18 to 20.5 inches long. Your own baby may have a weight and size of less or more, though, and still be normal and healthy.
As the baby’s weight and size increase throughout later pregnancy, so too does the activity the mother feels inside her uterus. From the beginning of the third trimester, the mother probably will notice the baby’s movements becoming more frequent and vigorous. She may notice a change in the movements at around 32 weeks. By that time, the growing fetus has made crowded conditions inside the uterus. The fetus is moving around just as much, but the kicks and other movements may seem less forceful. To keep track of the baby’s activity, your doctor may ask you to keep a record of when you feel your baby moving. A sudden drop-off or decrease in movement could signal a problem and should be reported to your doctor. She or he may want to perform tests to monitor the heart rate or observe the movements of the fetus. Many factors seem to affect the baby’s movements in late pregnancy. How much and when the mother eats, what position she is in, and sounds from the outside world have all been shown to affect fetal activity.
Many pregnant women who are busy and active don’t always notice the baby’s movements. The mother may want to check on her baby’s movements from time to time, especially if she thinks she may have noticed a slowdown in activity. To do this, the mother should lie on her left side for 30 to 60 minutes and note how often she feels the baby move. If she is recording her baby’s movements, her doctor will tell her what should prompt her to contact her or him. A commonly used figure is fewer than 10 movements in two hours. Along with the usual sensations of kicks and rolls, the mother may also occasionally notice a slight twitching, like little spasms. These are probably hiccups. Fetuses get them too. There is no danger to the baby from hiccups.