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Definition of dizygotic twins

by Alivia Nyhan
Published: Last Updated on

Twin pregnancies are an event for the family, and it is that having two fetuses growing at the same time and that they will be born in the same delivery is an exciting situation that, at the same time, can generate some anxiety in the parents.

A twin is understood to be two zygotes whose gestation and development co-occur in the womb; however, when determining what type of twin pregnancy it is, specialists usually refer to fetuses as monozygotic or dizygotic twins. If you wonder what dizygotic twins are and how they differ from monozygotic twins, in this FastlyHealarticle, we will explain it to you.

Dizygotic twins concept

Dizygotic twins are a double product of the same pregnancy, developed from two eggs released simultaneously by the ovary and fertilized simultaneously. They can be of the same or different sex and have a different physical and genetic makeup, and their placentas and membranes are distinct and separate.

Known colloquially as twins, dizygotic twins develop due to the fertilization of two different eggs by two other sperm simultaneously. The two zygotes develop independently in their placentas. At the genome level, twins are the same as any pair of siblings, so they could have similar physical characteristics or be completely different from each other. Because they are the product of the simultaneous fertilization of two separate eggs and two different sperm, dizygotic twins only share 50% of their genes, which is why they can be very different physically.

However, in addition to the physical difference, a curious fact in this type of pregnancy is that the babies could belong to two different parents if all the conditions are met. This event occurs when, once the woman releases her eggs, one of them is fertilized by a parent in a sexual encounter. Then, after a period of between 12 hours and 48 hours maximum, the other egg is fertilized by a man. Different in another sexual encounter. Both embryos will implant almost simultaneously and can give rise to a pregnancy of twins with different parents.

Is having twins inherited?

There are families in which we usually see more than one pair of dizygotic twins or twins, which immediately makes us suspect that the tendency to this type of pregnancy could be hereditary. Indeed, the fact that there are twins in our family increases the possibility of having a pregnancy of this type by 20%.

The frequency of dizygotic twin pregnancies is 1 in 80 pregnancies, but in women who have twins in their family, the possibility is reduced to 1 in 60. This occurs because the probability of ovulating twice can be hereditary, although not always. For a woman to produce two eggs, they will be fertilized by two different sperm.

Other causes that increase the possibility of pregnancy of this type are:

  • Being over 35 years old, women over this age have a greater chance of ovulating twice.
  • Being Caucasian or Black, both groups have a higher incidence of twins.
  • Previously had multiple pregnancies.

Does the possibility of having twins skip a generation?

We often hear things like: my grandmother had twins, so I have the possibility of having them because it skips a generation. Not at all! This is entirely false; if your mother has had twins, you can also have them; even being a twin, you could have a pregnancy of this type. This feature does not skip a generation and can be quickly passed on to the next generation.

If a man is a dizygotic twin, since he can ovulate, none of his children will be a twin unless his partner ovulates double. However, if you have a daughter, she will be able to inherit that 20% chance of having this type of pregnancy; this is why it is popularly believed that the trend skipped a generation.

What is the difference between dizygotic and monozygotic twins?

We have already made it clear that dizygotic twins are formed when two different eggs are fertilized, so they grow in separate placentas and share only half of the genetic load. But how are monozygotic formed?

The monozygotic twins are popularly known as identical twins, this type of pregnancy occurs when, for reasons yet unknown, a zygote divide and gives rise to two different embryos that can grow or not in the same placenta. This cell division gives rise to two fetuses with a similar genetic makeup and significant physical similarities.

In some cases, monozygotic twins are very similar or difficult to distinguish; however, in others, their phenotype is not so similar. Being the product of the cell division of the same embryo, they will always be of the same sex.

This article is merely informative, at FastlyHeal .com we do not have the power to prescribe medical treatments or make any type of diagnosis. We invite you to see a doctor in the case of presenting any type of condition or discomfort.

If you want to read more articles similar to Definition of dizygotic twins , we recommend that you enter our Medical Dictionary category .

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