How do Your Twins End up Fraternal or Identical?
You are, of no doubt, aware, that twins may be either fraternal or identical. However, what does it depend on? Fraternal twins get developed from two woman’s eggs, which were released during the same ovulation period and they were fertilized with two different sperms at the same time. These kinds of twins are called dizygotic. However, identical children get developed from one and the same egg, which becomes fertilized by two different sperms, then splits into two parts and these twins are called monozygotic.

It is clear, that if two babies come form the same egg, monozygotic twins share the same DNA, but, mostly these children are never completely identical. They do have the same genetic makeup, there are enough of characteristics, distinguishing them one from another, and usually their parents and close friends can easily tell them apart. It may be either because of some environmental conditions’ influence, either inside or outside the womb. It is also possible that some definite genes will be expressed in their own ways in each of the twins.

When and How Can You Get To Know If Your Babies are Dizygotic or Monozygotic?
There are some specific prenatal tests being conducted during the pregnancy period in order to get to know if there is anything wrong with the development of a fetus (es). These tests are chorionic villus sampling and amniocentesis; and they can tell you without much problems, whether the babies, you are expecting are dizygotic or monozygotic. Though, it is of course quite difficult to perform with twins or triplets, and, doctors may not be able to receive a sample of the DNA of each baby.

In case if these kinds of tests are not for you, the simplest way to find out is to have an ultrasound conducted. Doctor will see if your babies are monozygotic or dizygotic by looking whether there are one or two plalcentas, and whether the babies are of the same gender.

It is also possible to undergo a trans – vaginal ultrasound somewhere between the 9th and 14th weeks of pregnancy, which will help you to get to know if you are expecting dizygotic or monozygotic twins with nearly 100% certainty. In case if you undergo this kind of an ultrasound during the second pregnancy trimester, the accuracy of the result will be no more than 90%, because the uterus becomes more crowded.
 Thus, if your babies have one placenta, it means that they are monozygotic twins, if there are two placentas, found in your uterus, you are expecting dizygotic twins. According to the investigations, conducted, your twins may be dizygotic as well as monozygotic, if there are two placentas, found. Though, all dizygotic twins and 20 – 30% of monozytogic twins have separate placentas for each.

Somewhere during the period between the 18th to 20th weeks of the pregnancy, your doctor may be able to tell you your babies’ genders, in case if they are positioned in such a way, that the doctor will be able to have a look at their genitals. If the ultrasound shows you that you are expecting a boy and a girl, it is clear, that the twins are dizygotic, as monozygotc twins are almost always of the same sex.