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The age of an unborn child is most often defined by gestational age, which is measured from the first day of the last normal menstrual period. Because some women have irregular periods, other ways are also used to help date the pregnancy. One way is to measure the length of the unborn child by ultrasound. At fertilization (when the male sperm enters the female egg), the unborn child has his or her own unique set of DNA material—or genes—half from the mother and half from the father.
The DNA is the blueprint for growth and development of all cells throughout life. DNA determines all of the baby’s physical characteristics, such as gender; the shape of the nose and ears; and the color of the hair, eyes, and skin. During the first 8 weeks, the unborn child is known as an embryo. After that time the unborn child is known as a fetus. It is during the first ten weeks of pregnancy that the unborn child is most likely to be affected by things such as alcohol, nicotine in cigarettes or other tobacco products, some prescription medicines or over-the-counter drugs, illegal drugs (like heroin, cocaine, or marijuana), viruses (like German measles), X-rays, radiation therapy, accidental exposure to radiation, and vitamin deficiencies (such as folic acid). |
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At 18 weeks gestation the arms and legs begin to punch and kick. Fingernails are well formed. The unborn child can suck its thumb. Taste buds are present. Male or female gender is evident. A protective waxy coating is present on the skin.
At 20 weeks gestation some experts have conclude that the unborn child is able to feel pain. Skin becomes less transparent as fat begins to deposit. Eyebrows and lashes appear. Breathing-like movements become regular and are detected by ultrasound, but the lungs have not developed enough to permit survival if birth occurs. The unborn child turns its body. At 22 weeks gestation the rapid brain growth continues. Eyebrows and eyelashes are well formed. Eyes are fully functional and capable of movement. Vocal cords are active. Reflexes are present. Weight is about one pound. At 24 weeks gestation unique footprints and fingerprints are present. Outside sounds can be heard. Actions such as hiccupping, squinting, smiling, and frowning may be seen through ultrasound. Lungs have developed such that some premature babies may survive. Weight is about 1 to 11/2 pounds. At 26 weeks gestation the central nervous system is developed enough to control some body functions. Eyelids open, close and can perceive light. Lungs have further matured and breathing is possible. The unborn child exercises muscles by kicking and stretching. Weight is about 11/2 to 2 pounds. Length is about 9 to 10 inches. |