When morning sickness becomes protracted and severe. it is known by the awesome name hyperemesis gravidarum. Simple morning sickness can be most unpleasant and annoying, but it is not harmful to the mother or fetus. Severe hyperemesis gravidarum, on the contrary, is a serious complication because the repeated vomiting depletes the body of fluid and chemicals. The fundamental body processes can then become deranged. In the days when not so much was known about fluid balance and body chemistry.
it was not unusual to see pregnant women critically ill From this condition. Nowadays, fortunately, proper super• vision and treatment will avert these crises. As long as the weight is maintained, dehydration is not severe. A loss of ten pounds or more is a sign of severe dehydration. In these circumstances it is usually advisable to hospitalize patients and restore the fluids and chemicals they have lost through the repeated vomiting. Furthermore, we have drugs for this condition. Simple sedatives are often effective. Several newer drugs appear to act directly on the vomiting center in the brain and suppress its activity. No one knows the cause of hyperemesis gravidarum. It is much less of a problem now than it was a few years ago. partly because of our greater knowledge. Abnormalities can now be corrected rapidly and accurately before further trouble results.
Rare is the pregnant W0men who has not at some time half convinced herself that she is going to have twins. In actuality, twins occur only once in something like ninety births. The incidence of triplets is about one in nine thousand births. Multiple births of more than three babies are truly medical curiosities. Mothers who are going to have twins will often have more severe symptoms of pregnancy than those having single births.
Protracted and severe morning sickness is characteristic. If morning sickness has not been a problem in a woman’s previous pregnancies. its appearance this time makes one suspicious of multiple pregnancy. So does excessive weight gain in a woman who is watching her diet carefully and is not taking too much salt or drugs containing sodium. The symptom that usually tips the doctor off is the size of the uterus. which has become larger than it should be for that particular point in the pregnancy. When the doctor has an opportunity to make regular periodic examinations, he can tell whether the womb is enlarging too rapidly, but if he sees his patient only once in the latter part of preg-nancy, lie may easily miss the diagnosis.
Contingencies of this sort point up the value of prenatal care. Twins are usually diagnosed in the last three months. To be able to spot twins earlier requires a high degree of clinical judgment. ‘Elie probability of twins increases somewhat with the age of the mother and the number of her children. Once the doctor suspects twins, he can confirm the diagnosis by finding two separate heartbeats, which can usually be detected with his stethoscope. Several sophisticated electronic devices capable of demonstrating twin pregnancies have been developed recently.
It is possible as early as the fourth month to obtain fetal electrocardiograms from the electrical impulses generated in the babies’ hearts. Twin pregnancies will show two distinct waves in the fetal electrocardiogram. There are also electronic stethoscopes and sensitive amplifiers that can magnify the sounds of the baby’s heartbeat many times. While apparatus of this complexity is interesting and even exciting, it is mainly a research tool and at this stage of the game not essential to proper supervision of the usual multiple pregnancy. The doctor will often want to confirm the diagnosis of multiple pregnancy with an X-ray picture of the abdomen.
While we try to keep X-ray exposure to a minimum in pregnancy, the importance of the diagnosis of multiple pregnancy is of such magnitude that it far outweighs the theoretic objections to X-ray exposure. There are two types of twins, fraternal and identical. A close inspection of the placenta will disclose which is which. Fraternal twins come from two different fertilized ova and therefore may differ in sex, blood type, eye color, and any other genetically determined characteristic. They are three or four times more common than identical twins. They
arise when two eggs are released and fertilized at the same time. Some women tend to ovulate more than one egg each month, and they are the ones who tend to have repeated multiple pregnancy. That multiple births occur in some families more frequently than statistically expected suggests an hereditary factor. These twins are usually of the Internal type. You hear that twins “skip a generation.” but there is nothing to this theory. The tendency to twinning is present in some families but does not seem to follow any distinct genetic patient Some studies have shown that there is almost as great a tendency for the twinning characteristic to be carried by the male as by the female
. This might mean that some males produce sperm cells in a greater number or with greater ability to fertilize the ova. Racial differences have been shown to exist in the distribution of fraternal twins. The chances of producing fraternal twins are somewhat greater for blacks than for whites and somewhat less for Orientals than for whites. There appears to be no racial difference in the incidence of identical twins. There are certain relatively new drugs capable of inducing ovulation in women who are unable to ovulate spontaneously.
This is a big advance in the treatment of infertility due to failure of ovulation. One complication of this type of therapy, however, is multiple pregnancy. There have been numerals incidents of twin pregnancy and a relatively large number of higher multiple births. The multiple births that occur are of the fraternal type because these drugs cause several eggs to be released from the ovary at the same time. Identical twins derive from a single fertilized cell. Very early in embryonic life the developing ovum splits completely into two, and each half goes on to form a baby. This division probably occurs in the first week after fertilization.
In rare instances the fertilized ovum does not split into two until alter the amnion, or inner layer of the membranes, has begun to form. When this happens, both babies will develop in the same sac. This condition is dangerous because the babies may be-come entangled in each other’s cords. Otherwise, twins, whether identical or fraternal, are always in separate sacs. They rarely get in each other’s way. even during delivery. The placenta of identical twins are fused, and there is often a mixture of fetal blood supply between the two placentas.