Everyone knows twins can be the same or not.
However, there are several types of twin pregnancy. Identical twins are called monozygous (because they result from the fertilization of a single egg). While the different twins are known as dizygous (they result from the fertilization of two eggs by two different sperm).
The monozygous twins are genetically identical and have similar physical features. The small differences of monozygous twins are the product of environmental factors interference to their development. The twins may even have different gender and are not genetically identical.
In addition, the pregnancies are also classified according to the number of placentas and bags. The can have independent pockets and placentas or share the same pocket and placenta. For the obstetrician, it is very important to know the number of placentas because there are complications of fetal-fetal transfusion syndrome that occur only in of pregnancy (with one placenta).
Dans
the case of dizygous twins, we will always have two placentas, two bags and two babies.
In the case of of monozygous pregnancy, we may have:
(a) a placenta, a pocket or;
(b) a placenta, two bags or;
© two bags, two bags ".