The fœtal heart sounds are the most anxiously sought for of all the signs of pregnancy. They are conclusive. They not only determine the diagnosis, but afford valuable information during labor, and nurse and student should lose no opportunity of becoming familiar with them. The heart tones can be heard as early as the twenty-sixth week, but they become more and more distinct as pregnancy advances. They vary from 140 to 160 beats to the minute at the twenty-sixth week, and at term, from 120 to 140. When they rise above 160 or sink below 120, some danger threatens the child. The fœtal heart tones have no significance as an indication of sex.
Funic souffle is the sound made by the passage of blood through the umbilical cord when a loop accidentally lies under the tip of the stethoscope. It is synchronous with the fœtal heart tones, but of no great practical importance when the heart tones can be obtained.
Determination of the period to which pregnancy has advanced is sometimes important. This can be approximated by a calculation of the time that has elapsed since the last period, or from the date on which quickening has occurred. Measurement of the height of the fundus and comparison with such scales as Spiegelberg’s, may be carried out, but it is not often required.
A method of estimation in gross, that is approximately correct, in many cases depends on the observation of the steady growth of the womb.
Thus, the uterus rises out of the pelvis at the fourth month, and may be found well above the symphysis pubis. At the fifth month the fundus is midway between the symphysis and the umbilicus. At the sixth month it reaches the umbilical level. At the eighth month it is a little more than midway between the umbilicus and the ensiform cartilage, which it attains in another month, the ninth. Then it usually sinks a little, especially in primiparas during the last two or three weeks. This is called lightening.
CHAPTER IV
HYGIENE OF NORMAL PREGNANCY
The time of confinement can never be accurately determined, because the onset of labor is purely an accident, dependent on many factors. Furthermore, conception does not take place necessarily at the time of intercourse, and we have no means of knowing whether conception occurred just after the last period present or just before the first period missed. So there is always a possible error of three weeks.
Pregnancy in the human family normally lasts from 275 to 280 days, and the approximate date of confinement can be obtained by the following convenient rules:
1. Take the first day of the last menstruation, count back three months and add seven days.
2. Or, assuming that quickening occurs at the seventeenth week, count ahead twenty-two weeks from the day on which quickening was observed.