What are the twins?
In medicine, it is customary to single out 2 varieties of twins: identical and dissimilar. So, in the first type, the development of two children comes from one egg, which, as a result of division, leads to the formation of 2 embryos. With such a phenomenon as the heterozygous twins, the babies develop separately from each other, and the difference between the time of their conception can be from several hours to several days. They develop from 2 fertilized eggs, so they can have different sex.
Why is a multiple pregnancy a rarity?
The low frequency of birth of twins is partly due to the fact that most of these pregnancies end at an early age. With the advent of such a method of research, as ultrasound, it became known that not all multiple pregnancies ended as a result of twin genera. By natural selection, often one fetal egg in the process of gestation, even in the early stages, perishes and eventually disappears, or it can be completely empty, ie, without the embryo inside it.
It is impossible to plan the birth of twins, no matter how much Mother tried to do it. However, there are certain factors that can lead to the conception and birth of two babies at once. First of all, it's heredity.
What is the probability of giving birth to 2 twin children at once?
As already mentioned above, the probability of the birth of twins is transmitted through the generation by inheritance, and the unsuspecting woman whose mother was from a pair of twins (ie, the grandmother had twins pregnant), two children can immediately be born. In this case, the ability to conceive of twins is transmitted through the female line.
In addition, this fact has a direct effect on the age of the woman. So, with its increase, there is an increase in the synthesis of hormones, which can lead to the maturation of several oocytes. Therefore, in women in 35-38 years the chance to give birth to two children is increased.
Also, in the course of numerous studies, it was found that the duration of a light day exerts an indirect influence on the appearance of two children at once. So it was noted that the probability of the birth of twins in the spring-summer period increases significantly.
If we talk about the physiological characteristics of the female body, then there are more chances for the birth of twins in those women whose menstrual cycle is short, and is only 20-21 days. In addition, it increases the chance and anomaly of development of reproductive organs. In particular, such a pregnancy can occur with the two-horned uterus, i.e. When the uterine cavity has a septum.
In addition to the factors listed above, the conception of 2 or more children often occurs when IVF is performed, when 2 or 3 fertilized, and in some cases 4 eggs, are placed in the uterine cavity to increase the probability of pregnancy.
Features of labor in multiple pregnancies
The weight of twins at birth is also different from that of children born as a result of normal pregnancy. There are cases when babies weighing 1 kg appeared. However, in most cases, the weight of such children is about 2-2.2 kg.
Thus, it is possible to say with certainty that the appearance of twins is a rarity. Therefore, my mother should be glad of such a gift of fate.