How many Types of Twins are there? All about Twins

You had been trying for a baby for a while and then you get the news that you have conceived. The joy of having a baby is pleasure in itself but after a few weeks, you get to know more. More good news that you are not just having one baby; you are going to have twins (or maybe more)!

We know the excitement of having twins is overwhelming and somewhat frightening, as you have to prepare for more than one baby. This also makes you curious about knowing what, how, why and much more about the pregnancy and the babies. Are you excited to know more about your pregnancy? Let us take you on a short tour of how your twin pregnancy will be, the types of twins you can have, how to identify them and much more!


How many Types of Twins are there?

A new chapter of your life will be flourishing soon and you are going to get more than you expected! If you always wanted to have twins, you would be thinking more about how you could identify that you are having multiple babies. Well, the tests are the only thing that can confirm whether you are pregnant with more than one baby. However, you can mark up to some points and check for the signs of having twins.

Signs And Symptoms Of Having Multiple Babies

Increased HCG Levels

Having elevated HCG levels is a sign of pregnancy. However, higher HCG levels might indicate that you are pregnant with multiple babies. Nevertheless, this is not a deciding factor but just a factor to be considered. Studies also show that there are times when singleton pregnancies have elevated HCG levels. Therefore, jumping to a conclusion on this single factor is not advisable.

Abnormal AFP Test Results

AFP, which is an abbreviation for Alpha-FetoProtein, is screened during second trimester to detect any congenital anomaly or birth defects. In singular pregnancy, the AFP levels would range between 10 ng/ml to 150 ng/ml when tested between 15th to 20th week of pregnancy. A higher reading may mean a multiple pregnancy. Talking of anomalies and complications, you can talk to your gynecologist about these tests too.

Hiked Morning Sickness

Experiencing morning sickness is a sign of pregnancy. This happens because of pregnancy hormones. However, the morning sickness in the case of a twin pregnancy is extreme. However, you can be amongst the few moms who have a relaxed pregnancy and often don’t experience such symptoms.

Food And Smell Intolerance

There are times during pregnancy that you feel intolerance towards food and smell. Foods mentioned below can make you feel uneasy.

  • Green veggies
  • Meat and seafood
  • Caffeinated drinks- tea, coffee, etc.

However, the increased rate of this intolerance can subject to the chance that you are having a twin pregnancy.

Larger Size For The Gestational Age

You will experience a sudden increase in your weight and size as compared to the average gestational size and weight for that age.

Although you can check for the signs, we advise you that you must get an ultrasound done, as it is the only way to confirm the twin pregnancy.

The earliest time that you can get to know about the twin or multiple pregnancies is 10 to 14 weeks.

Experiencing Fetal Movement Early

Normally, in singular pregnancy, women feel fetal movement between 18-22 weeks. But there are chances that if you have multiple pregnancy, you might feel fetal movements, earlier than normal. Although, it is controversial to the medical studies, many women with multiple pregnancy report feeling fetal movement sooner.


Types Of Twins | Identical Twins And Fraternal Twins Difference

Often you must have seen twins who look similar and then some twins look different. There are 2 most common types of twins – Identical and Fraternal. However, there are some other less common types of twins namely Co-joined, Semi-identical, and more. This is because the type of pregnancy for both cases is different. Let us see how –

Identical Twins

The twins that look alike are called identical twins. The reason that the look similar is because they are developed from the same egg. It so happens that while the cellular division process, the zygote is divided into two different embryos that further happen to develop individually. Moreover, they remain in the same sack and may share the same placenta as well. However, since they are developed from the same zygote, they have the same traits. This means in almost all cases, the skin color, eyes, hair color, and other personality trait remain same for them to look similar.

However, some notable changes that can be traced in the identical twins that vary due to their difference of placement in the womb and on the space, they occupy in there.

These twins are also called monozygotic twins, as they are a product of the division of the same zygote.

Fraternal Twins

Another type of pregnancy that leads to having twins is the one in which the twins don’t look alike. These are called fraternal twins or identical twins. There are times that the mother might release two eggs during the time of ovulation. The conception of such twins happens when two different sperms mate with two different eggs. As the fertilization of both the zygotes happens differently, there are no chances that they will ever look alike. They grow as individual babies in different sacks. Since they are a result of different infusions, they don’t share similar traits.

These twins, also known as dizygotic twins, have different DNA and can be of different sex, appearance, and other factors. These twins are just like other siblings and might just share 50% of their chromosomes or not. Often the fraternal twins are conceived by older women that are above the age of 35. However, younger women too stand a chance to it.

Other Types Of Twins | Rare And Unusual Scenarios During Twin Pregnancy

Identical Twins With Different Sex

This case is as interesting as it is rare. It so happens that the zygote has XY chromosomes. While the division, one of the male loses its Y chromosome due to mutation and gets X0 chromosome. Thus, the twins are a girl and a boy. However, the female can develop issues later in life.

Semi Identical Twins

This happens when two sperms mate with a single egg. Further, to survive they get divide. However, having the same egg, they have the mother’s set of chromosomes the same. There are only about 0.3 reported cases in the world population of this case.

Conjoined Twins

These twins are identical twins that have part of their bodies joined. These twins don’t survive and the ones that survive can be separated depending on conditions. some doctors say that this is a result of the improper splitting of the egg, while some say that the zygotes united again after splitting.

Parasite Twins

In this case, one of them is dependent on the other. The dependent one is called parasite and it can look like a dysfunctional body organ. It can also happen that the parasite twin grows inside the body of the other twin. Alternatively, the twin may have a body but a dysfunctional heart so it is not alive.


In this case, the woman may be pregnant with a baby and yet get pregnant with another. It is called superfecundation, as women do not release eggs when already pregnant. In very rare cases, a woman can get pregnant with twins from different fathers in this case.  

Multiple Pregnancies

There have been cases of multiple pregnancies where women have triplets, quadruplets, and quintuplets. This can happen due to many reasons and conditions and the babies can be identical, fraternal or both. The infusion of multiple eggs with multiple sperms and division of the eggs can all happen at once in such pregnancies.

Twin types infographic elements in flat design. Monozygotic or Dizygotic Placentation of twins medical illustration and icons isolated on white background

Risks Factors During A Twin Pregnancy

Twin pregnancy or multiple pregnancies are subjected to higher risk. There can be conditions like

  • Premature delivery – The babies might be delivered during the 37th week.
  • High blood pressure
  • Heavy bleeding after delivery due to excessive stretching of the uterus.
  • High blood sugar
  • Weight of the babies being low as much as 5 pounds
  • Tearing away of the placenta from walls.

While the other types of twins are rare in case, the identical and fraternal twins are most common. You must get your tests and observations done regularly during pregnancy. This helps you find out the type of twins and if there are any circumstances that, you must know about.