## Not all are the same There are two basic types of twins: monozygotic and dizygotic. Monozygotic are identical twins from the same egg, same-sex, and very similar in appearance. Dizygotic are from different eggs fertilized at the same time. They may be of different sexes and vary greatly in appearance. ## There are also rare types of twins Siamese twins are single-egg multiples. Because of the incomplete separation of the fertilized egg, the twins are not completely separated from each other. They may share organs and limbs. Twins conceived by superfetation (repeat pregnancy): when the egg is fertilized, the woman's ovulation stops as the cycle is interrupted. However, a second follicle follows and another fertilization of the egg occurs, resulting in the birth of twins conceived at different times. As a rule, the second child is born prematurely. The children's birthdays are the same, but their ages are different. Twins from different fathers: heteropaternal superfecundation. This can occur as a result of the release of several eggs in the same ovulatory cycle and intercourse with different men. ## The likelihood of having twins The odds of having twins are 1 in 87, triplets are 1 in 6400, and four or more babies are 1 in 51,000. The main causes of multiple pregnancies include: - Genetic predisposition. - IVF (In Vitro Fertilization) and medical ovulation stimulation. Multiple spontaneous ovulation (often occurs within the first month after withdrawal of OCs). - Maternal age: in women over the age of 35, several mature eggs may be released and a second child may be conceived during a single ovulatory cycle. - Race: twins are more often born to women of African-American descent, and very rarely of Asian heritage. ## Knowing in advance Modern screening methods allow early diagnosis of multiple pregnancy. First, an ultrasound scan is performed, which immediately shows the number of fetuses and their condition. The levels of hCG (chorionic gonadotropin) and ACE (alpha-fetoprotein) are also determined — with multiple pregnancies, the concentration of these hormones increases 4-fold. In the first trimester, the woman herself cannot find out that she will have more than one baby, but starting with the second trimester, there is a sharp increase in the abdomen and a large weight gain (more than the norm for a single pregnancy). Fetal movements will be detected in several places at once. ## What to expect for the expectant mother Since the burden on a woman's body with a multiple pregnancy is significantly higher than that of a woman expecting a single child, the risk of complications increases proportionately. Anemia develops more quickly, as do toxicosis, gestational diabetes, varicose veins, and other problems typical of pregnancy. Multiple pregnancies often lead to isthmic-cervical insufficiency (ICN). The risk is particularly high with triplets and more, as the uterine cavity increases in pressure and becomes distended. For this reason, along with standard screening tests, a cervicometria (an ultrasound to determine the length of the cervix) is performed. The first cervicometria is scheduled at 16 weeks of pregnancy. To minimize the risks, you should visit the doctor and undergo an ultrasound examination with Doppler to diagnose the slightest abnormalities in fetal development. In case of any complications, you might be hospitalized. Taking any medications — including vitamins, dietary supplements, and herbs — must be coordinated with your doctor. Expectant mothers should rest and eat right as well as limit physiological and psycho-emotional stress as much as possible. ## The best way to give birth When choosing the mode of delivery, the obstetrician pays attention to the presence of complications in the woman in labor, the number of fetuses, and their size and position in the uterus. A multiple pregnancy is not a direct indication for a cesarean section. Natural delivery is possible in twin pregnancies. If all indicators are normal, the babies are in the longitudinal and head first position. In this case, the delivery is usually scheduled at 37 weeks. Cesarean section delivery is performed routinely if the babies are large, have a malposition, there are more than two of them, or if there are any complications. Surgical intervention can be performed urgently if the life of the mother or baby is in danger. ## Health of the newborns Immediately after birth, 25 % of twins and 75 % of triplets end up in the NICU. As a rule, twins spend 18 days there, triplets 30 days, and quadruplets 58 days. Due to premature birth and fetal hypotrophy, twins are 5.5 times more likely to suffer from cerebral palsy, and triplets 20 times more likely. There is also a high risk of other abnormalities in multiple gestation: twins have a 39 % higher risk, and triplets have a 97 % higher risk. If multiple pregnancy is diagnosed, you should be especially attentive to your health and follow all the recommendations of your obstetrician, undergo all the prescribed examinations, and consult a doctor if you have the slightest suspicion of a problem. Modern medicine can successfully treat most problems that occur in twins after birth, allowing them to catch up with their peers in all respects and grow up completely healthy.