In human pregnancy, pregnancy is usually unique, however multiple or twin pregnancies can occur. The proportion of twin pregnancy is one in eighty pregnancies, but at present, due to the increase in assisted reproduction treatments and the advanced age of mothers, the rate has risen to one in 45 pregnancies.
Twin pregnancy is understood as the pregnancy of more than one fetus. Twins are usually associated with two babies, but twins are the born from the same birth, can be two, three, four, five, or more.
Multiple pregnancies are not all the same, depending on the number of fertilized ovules and when the zygote division occurs, there are different types of twins: 70 percent are bivitelins (known as twins), between 25 and 30 percent univitelinos (known as twins), and a minimal proportion corresponds to triple, quadruple, quintuple, etc. pregnancies.
Although it is becoming more common, and most pregnancies do not present problems, twin pregnancy is considered as risk pregnancy. They have more complications associated with preterm birth as well as an increased risk of preeclampsia and diabetes. Complications rise exponentially in pregnancies of more than two fetuses, especially in cases where the placenta is shared.
The creation of twins is the result of a complex process of cell division, which in case of failure can lead to rare cases of twins. They are genetic errors that can occur in multiple pregnancies that prevent the two fetuses from developing normally. But it should be clarified that these cases are exceptional.
As we mentioned at the beginning, the advanced maternal age It is one of the causes for which twin pregnancies have increased in recent years. Women over 35 are more likely to conceive twins. Although from this age the chances of conceiving decrease considerably, certain hormonal imbalances increase ovarian follicular stimulation causing multiple ovules to occur.
The assisted reproduction techniques they are methods that resort to ovarian stimulation, and in the case of the invitro, two to three embryos are usually implanted to ensure the chances that at least one will thrive.
These are the main factors that influence that instead of being born twins in one in eighty pregnancies, currently occurs in one in 45 pregnancies. The question of whether this rate will continue to increase, the answer is that almost certainly, it will.
