Fertilization typically takes place within 24 hours after a sperm encounters an egg inside the fallopian tube. Only one of the millions of sperms will pass through the membrane of the female egg, or ovum. Once the sperm has fertilized the ovum, enzymes in the egg alter the inner membrane and make it impossible for more sperm to enter. Once introduced, the nucleus of the sperm and egg, each containing 23 chromosomes, unite to form one fertilized egg. The fertilized egg then travels to the womb where it embeds itself in the lining of the uterus and begins to grow.
A fertilized egg in the wall of the uterus will soon divide into many cells and begin to form the embryo's organs. Just five weeks after fertilization, the embryo develops a nervous system, skin, muscles, and internal organs. By the eighth week, the embryo is three centimeters long and has a complete nervous system, a beating heart, a fully-formed digestive system, and the beginnings of its unique facial features. By the 16th week, its heart and brain are well developed; and by the 26th week, its lungs are functional.
Nutrition During the Third Trimester
Approximately 10% of American women develop high blood pressure, or hypertension during pregnancy, most frequently in the third trimester. In most cases, the elevation is mild and produces no adverse symptoms. If it is not stabilized, however, it can result in kidney failure, liver damage, and seizures in the soon-to-be mother.
A 1992 study conducted at Brown University in Providence, Rhode Island, reported that low calcium intake (along with low magnesium and potassium intake) during pregnancy increases the risk of elevated blood pressure in the newborn. Pregnant women who consumed 1,000 to 2,000 milligrams of calcium daily, as well as their fetuses, had significantly lower risks of high blood pressure. A calcium-rich diet of foods such as low-fat milk, dairy products, sardines, salmon, caviar, almonds, and Brazil nuts effectively prevents high blood pressure.
Calcium supplements may also help prevent premature deliveries and low birth weight babies. Calcium supplements can have side effects, including constipation. The best advice is to consume all the recommended amounts of absorbable calcium through a balanced diet.
Virtually everyone knows what "stress" is, although it is especially important for a pregnant mother to understand how it affects her body and her fetus. During pregnancy, labor, and childbirth, the woman will experience a variety of stresses, some of which are unavoidable. In addition, she will also undergo substantial hormonal changes which will affect how she reacts to stressful situations. For example, she may feel more irritable, anxious, or fatigued as her baby becomes larger in the womb.
Biofeedback training is a method of learning how to consciously regulate brain waves, breathing rhythm, heart rate, and blood pressure. Biofeedback machines are simply computers with wires that attach to a patient's skin which measure important biological processes such as the heartbeat.
Chronic stress also increases the mother's heartbeat, and when her heart beats faster, so does her baby's. This influences the baby's development while inside the womb and also affects the baby's heart rate after birth. This was demonstrated by an interesting experiment conducted with a group of newborn babies. In the experiment, researchers played several tape recordings of a mother's heartbeat. When they played a tape of a normal heartbeat of the mother, the babies became quiet, breathed evenly, ate well, and gained weight. When the recording of the heartbeat was speeded up above normal, the same babies became restless and began to cry.
Biofeedback has many beneficial uses during pregnancy. In the latter part of her pregnancy, for example, a mother may find that her legs and feet become painful, or that she develops varicose veins—swollen leg veins caused by increased blood pressure due to the weight she has gained. In some cases, these symptoms result because she places a disproportionate amount of weight to one side of her body.
Three to five percent of all pregnant women develop diabetes during pregnancy, usually during the second trimester. Pregnant women with diabetes will find practicing asanas especially beneficial.
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