What is multiple pregnancies?


Multiple pregnancies is one in which two or more babies develop simultaneously in the womb.


In mankind, it is normal to conceive children one by one, a pregnancy with more than one embryo is considered unusual and is framed within high-risk pregnancies. This does not mean that it always has to be complicated, but it is more frequently associated with some diseases or complications of pregnancy. Therefore, it is necessary to undergo tests to rule out problems and follow the indications that professionals advise.


In recent years, the number of multiple pregnancies has increased due to assisted reproduction treatments (1-3%), and due to both maternal and fetal complications that can occur, we believe that this is an issue of great importance.


Multiple pregnancies is diagnosed by ultrasound around week 12 is when it is determined how many babies there are. Chorionicity is the main factor that determines the prognosis of pregnancy. Only up to 14 weeks can one of these two pregnancies be reliably determined:


Dicorial gestation: 2 placentas


Monochorial gestation: 1 placenta


Twin pregnancy types




It is the most common 80% of twin pregnancies. The doublets also called bivitelline or dizygotic twins, result from the fertilization of two different ovules by two sperm.


Each fetus develops in its amniotic sac and feeds on its placenta (although these can join together and give the impression that they are one).


The twins can be of different sexes and not look like anything physically since they come from two ovules and two sperm. They may even have been conceived through different intercourse, as some women ovulate twice in one cycle. In fact, 50% of these twins are different-sex couples and the other 50% of the same.




The other possibility (in 20% of cases) is that the fertilized ovum splits into two equal parts. The result is two univitelline or monozygotic twins.


Depending on when the division occurred, fetuses may or may not share the placenta (most do). In 99% of cases, children are in separate amniotic sacs. When it is not, there are more risks, and the control of the pregnancy must be exhaustive.


They are always the same sex because their genetic blueprint is exact. They are so equal that it is difficult to differentiate them.


Other multiple pregnancies


An even less frequent case is the pregnancy of more than two children, which always comes from different ovules’ fertilization.


A few years ago, multiple pregnancies resulting from artificial fertilization were common, but children were often born prematurely, and not all of them always survived. For this reason, only a maximum of three embryos are allowed to be implanted at a time, and if the woman is older than 38 years, only two are implanted.


Does genetic inheritance influence have twins or twins?


Twin pregnancies are more common in women with a family history (when the mother or a grandmother has had twins). The cause is that these women ovulate twice, therefore there are two ovules ready to be fertilized, even in different intercourse.



These pregnancies are also more frequent infertility treatments since a higher production of ovules is artificially caused. In in-vitro fertilizations, more than one embryo is implanted in the woman at the same time. Almost one out of every two twin pregnancies is the result of fertilization treatment.


Another reason for the increase in multiple pregnancies is the increasing age of mothers. The older, the higher the concentration of follicle-stimulating hormones (FSH) and the more frequent the presence of several ovules that can be fertilized. To know more about multiple pregnancy visit our website.