Overview of Di/Di Twins

Overview of DiDi Twins

Overview of Di/Di Twins: It’s been apparent in the last few years that twins are becoming increasingly the norm. If you’ve discovered you’re expecting twins (or recently came across an entire family that has a pair of twins) You might be wondering why this happened?

How did two infants become a couple and how genetically similar do they look? They might share the identical birthday, but do they have identical placentas? Do they have the identical genes?

What are di/di twins?

When someone speaks of twins they’re talking about two infants that are born in the same pregnancy scare however, this could happen in a variety of ways. In reality the phrase twins is a broad term!

Two of the main categories twins are usually classified into are fraternal and identical.

They are also called monozygotic twins because they were born from the identical fertilized egg. (Identical twins form when sperm and egg meet as normal. One egg splits into two within a few hours upon fertilisation.)

Since identical twins originate from the same egg or sperm, their chromosomes will be the same that means they’ll have the same sexe and will share the same genetic traits (e.g. hair, hair color and the color of eyes).

On the other hand fraternal twins have only 50% of their chromosomes, just like other siblings share. This means that they appear very similar or completely different. It could be that they are different genders with different colors of eyes and hair or even the same sex, and appear very similar.

Still here? But there’s more to the story than whether they’re fraternal or identical should you be interested in what happens when a twin set has evolved. The kind of twins (fraternal or identical) and the rate at which their development determines if the twins were part of the same amniotic sac or were in amniotic sac and chorionic sac Trusted Source.

You’re probably considering… what exactly is the chorion? (And while we’re there What is an amniotic sac or amnion?) What’s the significance of amnion and amniotic sacs?

The chorion forms the outermost membrane of the fetal body. The chorion connects the amnion Amniotic fluid, and embryo to the placenta. It also aids in the development of the placenta.

What is the significance of this? If two twins share a chorion they’ll share a placenta. If twins have a separate chorion they’ll have two different placentas.

The amnion, on the other hand , is the fetal’s innermost membrane. It shields the fetus and contains amniotic fluid. As with the chorion as well twins, twins may share an amnion, or they can have one of their own.


In a di/di pregnancies (more known scientifically as the dichorionic diamniotic pregnancy) the twins have an amniotic and chorionic sacs. The basic idea is that each baby grows the same way as a singleton, however only a bit larger, due to being born in the same womb.


A mo/di pregnancy (more than just monochorionic diamniotic pregnancies) the twins share a chorionic sac however, they have amniotic sacs that are different. In simple terms, the distinction between a di/di pregnancy and mo/di pregnancy is that mo/di pregnancies only involve one placenta.


In the case of a month/month pregnancy (more known scientifically as monochorionic, monoamniotic pregnancy) twins share amniotic and chorionic sacs. This is a result of having one placenta and one amniotic sac that is shared between the two babies. Since the babies share lots of their time, mo/mo pregnancies aren’t easy and require constant surveillance!

How do you know whether you are suffering from di/di pregnancy?

Although it might seem as if an ultrasound is the best way to give everything you need to know, the reality is that it isn’t. Source in determining di/di/mo/di and mo/mo pregnancy.

Ultrasounds are the most reliable method for diagnosing chorionicity during the first trimester. The signs that could suggest a pregnancy with di/di on an ultrasound taken in the first trimester include:

  • two gestational sacs that have an echogenic chorion that is thick around each embryo
  • A thick inter-twin membrane
  • The twin the peak sign (it appears like an upside-down letter the letter Y)
  • Two yolk sacs ( This won’t tell whether it’s a m/di or an di/di pregnancy!)

Are di/di twins identical , or fraternal?

Di/di pregnancies comprise most of the majority of twins and can result in identical twins or fraternal twins.

All fraternal twins have di/di however, identical twins may additionally be di/di. What is the reason for this?

However identical conception begins by combining only one egg, and one sperm cells, however at some point, the one egg splits. This alters the growth of the amniotic sac.

If there’s an unification of the zygotes between one to four days following fertilization, it’s more likely to result in the di/di twin setup.

If an ultrasound test shows that you’re carrying one of the sexes and it’s evident that two twins share a fraternal. But, if they have the same sex it’s not clear the degree to which they’re similar.

Are there any risks associated with the di twins?

It is true that being pregnant with twins is not without other risk factors. Although a di/di pregnancy has the lowest chance of complications in twins anyone who is carrying twins is at chance of problems regarding the placenta or intrauterine growth restrictions (i.e. babies that outgrow the space available! ).

Certain issues which are more likely with twin birth are:

  • Previa placenta. A larger or heavier placenta resulting from having twins is much more inclined to lie lower and over the cervix, making normal delivery a risk.
  • Abruption of the placenta. A larger or heavier placenta resulting from twins is more likely to separate from the wall of the uterine.
  • Placingnta Acreta. This occurs when the placenta is inserted too deeply to an uterine wall.
  • The term “premature” refers to. Because of limits on the uterine cavity and the possibility of other issues that suggest the possibility of a birth earlier is advantageous twins are at a higher chance of being born prematurely (before the 37th week of gestation).
  • Birth weight is too low. Since twin babies are born sharing space within the uterus, and could require birth slightly later than to be full-term babies, they have greater risk of being born with a low weight.
  • Gestational Diabetes. This can be caused because blood sugars are excessively high.
  • Gestational Hypertension. This is the result of high blood pressure during pregnancy.
  • Hemorrhage postpartum. One potential reason for hemorrhaging following the birth is because the large placenta created by having twins has caused the uterus extend more than normal.

If the twins share the same placenta it is possible that one baby will receive more oxygen and nutrients required for growth. This is a problem that occurs in about 13% of pregnancies with twins that are more than one month.

This inequitable division can result in issues like twin-to-twin transfusion syndrome (TTTS), twin anemia polycythemia sequence (TAPS) or the selective intrauterine growth limitation (SIUGR). Therefore, pregnancies with mo/di must be monitored more closely.

The highest risk of risk occurs when twins share the amnion and the chorion during an early pregnancy. Since there is no way to distinguish twins from one another during the womb, there is a chance of cord getting entangled.


In or out of the womb, twins’ development is often confusing, and present additional issues. (Don’t worry , they be a source of double joy!)

If you’re nearing becoming an identical twin You’re likely to have lots of concerns about their genes and the process that led them to become. Certain queries can be resolved through ultrasound. Other questions will only be found by genetic tests.