3. Softening of the cervix occurs, as a rule, about the beginning of the second month. In some cases, such as certain inflammatory conditions and in carcinoma, this sign may not appear.
4. Painless uterine contractions, called Braxton Hicks from their first observer, begin during the early weeks of pregnancy and recur at intervals of five or ten minutes throughout the entire period of gestation. The patient is not conscious of these contractions, but they may be observed during the early months by bimanual examination, and subsequently by placing the hand on the abdomen. One feels the uterus growing alternately hard and soft as it contracts and relaxes.
But all of the probable signs of pregnancy, like the presumptive symptoms, may be simulated in non-pregnant conditions; hence the appearance of any one of them alone may not be deeply significant. But two or more occurring coincidently constitute strong evidence of pregnancy.
The positive signs of pregnancy, of which there are three, are not apparent until the 18th or 20th week, and all emanate from the fetus.
1. Hearing and counting the fetal heart beat is unmistakable evidence of pregnancy. The sound of the fetal heart beat is usually likened to the ticking of a watch under a pillow. The rate is from 120 to 140 per minute, being about twice as fast as the maternal pulse. So long as its rhythm is regular, however, the rate may drop to 100 or increase to 160 beats per minute without being considered abnormal, or indicative of trouble with the fetus.
2. Ability to palpate the outline of the fetus is also a positive sign of pregnancy, if the head, breech, back and extremities are unmistakably made out through the abdominal wall.
3. Perception of active and passive movements of the fetus is accepted as a third incontrovertible sign of pregnancy. There is some difference of opinion concerning the value of “quickening” alone as a positive sign of pregnancy. But if the fetal movements are also perceptible by the obstetrician through the mother’s abdominal wall or by vaginal examination, there can be no doubt about the diagnosis. The movements felt by placing the hand upon the abdomen are termed active movements, while the passive movements result from internal or external ballottement. Ballottement is accomplished by giving a sharp or sudden push to the head or an extremity, and feeling it rebound in a few seconds to its original position. Passive movements may be felt early in the fourth month, and active movements after the 18th or 20th week.
PHYSIOLOGY OF PREGNANCY
A general understanding of the physiology of pregnancy is indispensable to an appreciation of the importance of observing the present-day teachings about the hygiene of pregnancy. Upon this, in turn, must rest intelligently administered prenatal care, one of the most important branches of obstetrics.
The physiology of pregnancy really represents an adjustment of the various functions of the maternal organism, which are altered to meet the demands made upon the mother’s organs by the body which is developing, growing and functioning within hers. These adjustments are in the nature of an emergency service, since they come into existence and operate only while needed, which is during pregnancy, and promptly disappear when the need for them ceases with the birth of the child. The mother’s body then begins to return to its normal, non-pregnant state, which, with the exception of the breasts, which function for nine or ten months, is accomplished in a few weeks.