What is Multiple Pregnancy?
Being pregnant with more than one baby is called a multiple pregnancy. Twin, triple and quadruplet pregnancies are types of multiple pregnancies. The most common multiple pregnancies are twin pregnancies. The probability of twin pregnancy is approximately 1 in 85.
Twins are divided into two groups: identical twins, monozygotic, and fraternal twins, namely dizygotic. About one-third of all twin situations are monozygotic (identical) and two-thirds are dizygotic (fraternal) twins.
Fraternal Twins (Dizygotic Twins)
Fraternal twins occur as a result of the fertilization of more than one egg cell with more than one sperm in the same menstrual period as in infertility treatment. For this reason, they are not genetically identical to each other. Approximately 30% of dizygotic twins are of different sexes, while the remaining 70% are of the same sex.
Fraternal twins are particularly common in pregnancies caused by stimulation of the ovaries in infertility treatments.
Identical Twins (Monozygous Twins)
When the fertilized egg splits into two, monozygotic twins occur. Twin pregnancies with different characteristics occur depending on when this splitting takes place.
If the egg splits into two within the first 72 hours after fertilization, two babies, two amniotic membranes and two placentas are produced. (diamniotic, dichorionic) If bifurcation occurs between 4 and 8 days, since the placenta is formed during this period, two babies, two amniotic membranes and a single placenta are formed. (diamniotic, monochorionic) It is the most observed twin pregnancy. In the division that will occur on the 8th day, two babies, an amnion and a placenta are formed. (monoamniotic, monochorionic) Divisions beyond this point result in the development of conjoined twins (Siamese twins).
How to Distinguish Identical and Fraternal Twins?
Twins that share a single placenta are always identical twins. Twins of different sex are always fraternal twins. It is not so easy to distinguish single or double eggs in pregnancies with two different placentas and two babies of the same sex. It requires some testing. In the follow-up of twin pregnancy, it is necessary to evaluate the placenta and amniotic sac conditions of the twins in the first 15 weeks by ultrasound. After this period, evaluation becomes very difficult.
What Increases the Chance of Twin Pregnancy?
Fraternal twin pregnancy rates are thought to be affected by factors such as infertility treatment practices, racial differences, presence of twins and triplets in the family (genetic factors), age of the expectant mother, and hormonal changes. It is possible to say that the incidence of identical twins in different societies is approximately the same. 30% of fraternal twins are different sexes and 70% are the same gender.
Other multiple pregnancies, such as triplets or quadruplets, are similar to twin pregnancies. Triplets are formed when the fertilized egg divides into two, and then one of the parts divides again.
When and How Are Twin and Multiple Pregnancy Diagnosed? – Symptoms and Diagnosis
If the uterus (uterus) is larger than expected and multiple fetal parts can be palpated during the examination, this suggests the possibility of multiple pregnancy. In such a case, it is possible to make a definitive diagnosis with ultrasound. Starting from the last menstrual period, as of the 6th week, two gestational sacs in the uterus can be noticed. An increase in beta hCG values in the blood is also seen in multiple pregnancies. With these methods, twin pregnancy and multiple pregnancy can be understood.
In some cases, although these two sacs are noticed or even two fetuses are observed, the number of fetuses may decrease to one in the following periods. This situation, which is called vanishing twin syndrome, can be observed relatively frequently. If a twin is detected in the early period, ultrasound follow-up should be increased in order to avoid any problems. It is not possible to prevent or treat vanishing twin syndrome in today’s conditions.
Risks in Twin and Multiple Pregnancies
Multiple pregnancies are classified as risky pregnancy due to the possibility of harming the mother and the babies. Nausea and vomiting are more common in multiple pregnancies due to the increase in the amount of hormone secreted in the mother (hCG hormone). Iron deficiency anemia in pregnancy can be experienced more intensely. The amount of food that the mother should take increases compared to normal pregnancies. This increase is approximately 300 calories per day.
The probability of preterm birth (preterm birth) also increases in twin and multiple pregnancies. For this reason, an experienced medical team should be involved during and after the birth. There are studies showing that the mean gestation period decreases as the number of fetuses increases. The risk of miscarriage may also be greater in multiple pregnancies, so physical activity in the mother may need to be reduced. 28-30 days of taking a break from work. It is recommended to start after weeks.
Pregnancy-related high blood pressure (hypertension), preeclampsia, eclampsia (pregnancy poisoning) are also more common in multiple and twin pregnancies.
The chance of having defects in the placenta increases. It is possible to see more amniotic fluid than normal (polyhydramnios) in one or both sacs. The possibility of disturbances in the fetal posture and the possibility of difficult delivery are also increased. Possible bleeding can be seen with the tension of the uterus. With the disproportionate vascularity among babies, excess blood and anemia may occur. The risk of congenital anomalies in babies is also higher in multiple pregnancies.
Twin Pregnancy / Multiple Pregnancy Delivery Types
In cases of triplet and quadruplet pregnancy, the cesarean section method is preferred. In the case of twin pregnancy, there are physicians who recommend both normal and cesarean sections.
Cesarean section is definitely preferred in cases of monoamniotic, conjoined twins, the way they come from the babies (they do not reach the birth canal with the head), there is a big difference between the weights of the babies and their weight is less than 1.5 kilograms. Apart from this, the situations in which the cesarean section method can be preferred include differences of opinion among doctors.