STAGES OF PREGNANCY.
It is almost impossible to determine, month by month, the stage of pregnancy. Accurate knowledge about the beginning of pregnancy is usually lacking. Between the last normal menstrual epoch and the first missed menstruation there is an interval of at least three full weeks, during which conception may have o'curred. This opens the way for consider able error. The usual way is to add ten to the time of the last regular menstruation, and to date pregnancy from that point, but every obstetrician recognizes the unreliability of this method. This accounts for the so-called anticipations or retardations of labor, which have no real existence, but are due to errors of calculation. We will not attempt to follow the development of pregnancy, month by month. There are, however, three stages of pregnancy during which, in physiological utero gestation, the woman being well proportioned, the size of the foetus moderate, the quantity of amniotic fluid normal, and the presentation regular, one finds practically the same conditions. These three epochs are at three months, six months and at term. At the third month, the fundus uteri reaches to the level of the superior strait, or somewhat higher. The softening of the cervix is very distinct, and embraces both the mucous membrane, and deeper tissues of the inferior third of the cervix. The external os, which is closed in primipara3, allows the intro duction of the finger, in multiparR. The mammary changes are evident, the inferior uterine segment is larger and plainly rounded, and, in some cases, one hears the uterine souffle and the fcetal heart-sounds. At the sixth month, the fundus uteri generally reaches between one or two finger breadths above the navel. The cervix is softened throughout two thirds of the vaginal portion. The os, closed in primiparEe, is open in mul tiparEe. The breast signs are strongly marked, and milk is present (colostrum). The fcetal movements are very plain, and one clearly obtains abdominal and vaginal ballottement. The uterine souffle, and the heart sounds• are heard best at this time. The umbilicus is almost effaced. At nine months, the fundus reaches the false ribs, but is lowered a few days before confinement. The cervix, which retains its full length, is softened throughout, and closed in primiparEe. In multiparEe it is
funnel-shaped, the lips of the osexternum are everted, and the internal os slightly patulous, so that it is often possible to penetrate into the cervical cavity. The foetus or less engaged, (both in primiparEe and multiparEe); ballottement with impulse disappears, while ballotte ment without shock often remains. Mechanical disturbances of the digestion, and the respiration, are sometimes well-marked. During the last days of pregnancy, the abdomen often sinks, the movements become more free, more or less diarrhoea exists for twenty-four or forty-eight hours, irregular uterine contractions appear at various intervals, and palpation shows the •cervix to have been taken up. There is a general sense of comfort, and of deceptive which is only the prelude of parturition. Ahlfeld and Runge have attempted to calculate the stage of pregnancy from the size of the foetus. Ahlfeld invented compasses for the purpose, one branch of which, placed in the vagina, rests upon one pole of the foetal ovoid, while the other branch is applied, externally, upon the superior pole of this ovoid. Ahlfeld concludes that the diam eter so obtained is about equal to one half the real length of the fwtus. This method is liable to yield erroneous results.
What has been said about the typical conditions obtaining at three, six, and nine mouths, applies only to women with normal pelvis. In women with contracted pelvis the fo?tus, resting above the superior strait, elevates the fundus notably, so that, if reliance were placed upon this uterine elevation alone, in calculations regarding the stage of pregnancy, we would be exposed to grave errors. One of our colleagues was thus led to produce abortion, supposing that he was about to undertake a pre mature delivery. Deceived by the elevation of the uterus, and convinced by the repeated assertions of the patient that the last menstruation had occurred eight months before, our colleague induced labor as he supposed, at 71- months (the pelvis had a diameter of 2i inches). The child was born alive, but its development was that of 6 months, at the outside, and it died in a few hours. It was not viable. This shows the impor tance of exactly calculating the stage and duration of pregnancy.