Pregnancies in which there is more than one baby in the uterus are called “multiple pregnancies”. They are named twins if there are two babies, and triplets if there are three babies, etc. While normally 1 in 80 pregnancies are seen as twin pregnancies, there has been an increase in multiple pregnancy rates in recent years with the more frequent use of in vitro fertilization (assisted reproduction) methods. Multiple pregnancies are classified as high-risk pregnancies because they carry many risks.
The most common type of multiple pregnancy is twin pregnancy. Fraternal twins (dizygotic twins) are formed by the fertilization of two separate egg cells by two separate male cells (sperm). Fraternal twins constitute a less risky group among twin pregnancies. They can be of different or same sex. Siblings are not the same. Two siblings are similar to each other in proportion to their similarities. Identical twins, on the other hand, consist of a single female and male cell. Therefore, siblings are the same as each other, both genderwise and physically. They constitute the more risky group of twin pregnancies.
The fertilized cell can be divided into 4 different types according to the division time.
- Identical twins (diamniotic, dichorionic identical twin) with two separate water sacs and two separate baby partners (placenta). In terms of their pregnancy structure, they are similar to fraternal twins. It constitutes the least risky group of identical twins.
- Identical twins (diamniotic, monochorionic) with two separate water sacs and one baby partner (placenta): The risk is increased due to having a single placenta.
- Identical twins with one water bladder and one baby partner (monoamniotic, monochorionic): Having a single water bladder increases the risk slightly. In particular, the risk of cord entanglement has increased.
- Conjoined twins: Their chances of survival vary depending on the level of adhesion and the fact that their organs are common.
What factors affect twin pregnancy?
The incidence of identical twins is 1 in 250 births. There is no factor affecting its incidence. Race, familial predisposition, maternal age and number of births, maternal nutritional status and infertility treatment can be counted as factors that increase the incidence of fraternal twins.
How is the diagnosis made?
Diagnosis of multiple pregnancies has become easier with modern ultrasonography devices used today. The type of twin pregnancy can also be determined by ultrasonographic examinations, especially in the first trimester of pregnancy.
What are the risks in these pregnancies?
- Increased risk of miscarriage.
- The rate of congenital anomaly has approximately doubled.
- Birth weights of babies are lower than singleton pregnancies.
- One of the most important risks is premature birth. The average gestational week of twin pregnancies is 36-37. week. In other words, it is 3-4 weeks earlier than singleton pregnancies.
- Mortality rate in utero has increased for single water sac twins.
- Twin-to-twin blood transfer syndrome: It is seen in 15% of pregnancies with a single baby partner (placenta). Especially the risk of losing the smaller baby in the womb has increased.
- In multiple pregnancies, diseases associated with pregnancy nausea-vomiting and high blood pressure are more common.
- The rate of cesarean delivery of these pregnancies has increased.
How is the follow up carried out in multiple pregnancies?
As the nutritional needs of these pregnant women increase, the calories and iron they take should be increased. They should be followed closely in terms of the risk of preterm birth. At 22 weeks of pregnancy, the cervix should be measured by ultrasonography and care should be taken in the follow-up of patients with less than 25 mm.
How is the mode of birth determined?
In twin pregnancy, if the head of the first born baby is ahead, normal delivery can be made. If the breech of the second baby is leading or sideways, the experience of the physician who will perform the delivery is very important. If the first baby’s breech is ahead, or in the side position, it is delivered by cesarean section without trying a normal birth. Triplet and quadruplet pregnancies are delivered by cesarean section without trying a normal birth.
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