Wednesday, 28 May 2014


While the development of the embryo and fetus is progressing in the dark confines of the uterus, all the functions of the  expectant mother's body are  adjusting to the needs of  pregnancy. The basis of all these changes is the effect of the sex hormones oestrogen and progesterone, which are  manufactured by the  cells of the  placenta from its  earliest  days. The  changes start very early in pregnancy,  and most of them anticipate the demands that the  fetus will make on its mother for oxygen, for food and to get rid of its wastes
. In  the early weeks when the embryo's organs are forming at  an  incredible rate,  the  mother easily supplies the required oxygen and foods, in the later fetal weeks, when its growth is increasing even more,  the fetus needs larger supplies of  oxygen and nutrients for a longer period. The mother's  body adjusts to these demands by quieting down her own function's so that nutrients stay longer in her blood, and are more easily extracted   by the placenta for the use of the fetus. Further energy is spared by the placidity which is  common in a pregnant woman. Her muscle tone is reduced,  she does less, and because the energy is not burned up, it is stored as fat deposited in her breasts,  on her thighs and on her hips. But the slowing of her body functions has some disadvantages. Her gut is less active so that her stomach empties more slowly and constipation is common, her kidneys receive a higher  concentration of nutrients in her bloodstream and more are filtered  out to be lost in the urine. This is part of the price she pays, but it is not difficult for her to compensate for this loss by a balanced diet.
The need for the placenta to receive a large quantity of blood from which to extract the nutrients required by the baby is met by a 40% increase in the volume of the  mother's blood and by its more rapid circulation through her blood vessels. She manages to achieve this by increasing the amount of blood that the heart  pumps out with each beat and by increasing the rate at which the heart beats.  This is why some women are conscious of the action  of their heart in pregnancy and complain of palpitations. More blood is pumped around the body more rapidly. The red blood takes up more oxygen in the lungs and as nutrients are held  longer in the bloodstream, these and oxygen can be more readily given to the baby across the placenta.
As has been noted, this exchange takes place through the special cells which form the placenta and the mother's blood and that of  her baby are kept separate  at all times. The blood of the fetus passes through its body, then out along the vessels of the umbilical cord and through the network of fine cell vessels in the placenta which is composed of cells  of the outer part of the fertilized egg. Each time  the mother's heart beats, her blood is pumped in spurts into  the  placenta, carrying with it the nutrients and oxygen. In fact, the placenta acts as a very efficient lung, kidney and bowel for the fetus.
In general, an expectant mother should avoid taking drugs during pregnancy  unless  her doctor says that they are necessary. Alcohol crosses the placenta and when an expectant mother drinks excessively,  it may cause damage to her baby.
A pregnant woman may have nausea and may vomit  during the early weeks of pregnancy. Her  breasts are larger and heavier than they were in the past. She urinates more frequently,  is easily  tired  and may sleep longer at night. Backache is common as the back muscles stretch. Some women develop swelling of the ankles, have  episodes of aches and some have marked discomfort.

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