Chances of Having Twins

Many women and their partners want to know how they can increase their chances of having twins. Are there sexual techniques that can do the job or do you need reproductive technology in order to have twins? Whether or not you are interested in having twins, or even if you want to try not to have twins, this article will show you the chances of having twins and different factors that may contribute to your chances.

What Are the Chances of Having Twins?

Before answering this question, you should know that there are actually two types of twins. They come about in different ways and one type of twins is more common than the other.

  • Identical Twins. These are often known as monozygotic twins. You can have monozygotic twins when a single female egg is fertilized with a single male sperm. Sometime during the early division stages of the zygote, one or more cells break off and grow separately from the original zygote. They carry the same DNA and are identical. Because monozygotic twins come from the same fertilized egg, they are always going to be of the same sex and will look extremely similar to one another.
  • Fraternal Twins. These are also called non-identical or dizygotic twins. They occur when the mother releases two separate eggs at the same time. Each egg is fertilized and both grow separately in the female uterus. Fraternal twins are basically the same as having two siblings born at the same time. These types of twins are more common than identical twins, particularly with the increase in IVF procedures. They can be of the same or different gender.

The incidence of identical twins is about 3.5 out of 1000 live births. This incidence rate has been about the same over the years. Throughout the world, about 12-16 out of 1000 couples are able to conceive twins naturally. This is a very small rate. However, in the US, about 33 out of 1000 couples gave birth to twins in 2010. The chances of having fraternal twins have increased by nearly 76 percent. This is primarily due to the rise in reproductive fertility treatments like IVF as well as some other surprising reasons.

What Affects the Chances of Having Twins?

Every woman has about the same chance of having identical twins as the incidence of identical twins is not hereditary. The splitting of a single egg into two developing zygotes is a completely random event and is a relatively rare occurrence.

There can be a genetic basis, however, to having fraternal twins. Fraternal twins, as mentioned, happen when a woman releases two eggs at the same time. Each egg is fertilized by a different sperm, leading to infants that are genetically different. If the mother has an increased chance of having twins in her family, she will be more likely to release more than one egg per cycle. However, the genetics of the father is unrelated to having this type of twins. The release of more than one egg per cycle is also known as hyper-ovulation. This is controlled by genetic factors. Women who have a higher chance of having twins that are fraternal carry more genes related to hyper-ovulation.

What other factors do play into the chances of having fraternal twins? Here are a few more:

1.  Location and Ethnicity

Scientists have found that a person's ethnicity plays a large role in the chances of having various types of twins. Location also seems to play a role.

For example, in Nigeria, the Yoruba tribe carries the greatest risk of having twins at about 45 to 50 sets of twins per 1000 births. If you are of Nigerian decent and live somewhere else in the world, your risk of having twins is about the same as everyone else.

In other places, such as Central Africa, there are about 18 to 30 sets of twins per 1000 births. People who live in Southeast Asia, South Asia, and Latin America (or who are of these types of decent) have the lowest rate of twins, at a rate of about 6 to 9 sets of twins per 1000 births. If you live in Europe or North America and are Caucasian, you have a medium rate of having twins at only about 9 to 16 sets of twins per 1000 births.

However, do things like lifestyle, climate, or diet alter the risk of having twins? No one knows.

2.  Body Type

Twins tend to occur more commonly in women who are tall or are large in body type. Women who are obese and have a body mass index of 30 or greater have a 1.5 times the chances of having twins when compared to women who have a normal body mass index. Interestingly, these women tend to have twins of the opposite gender than the same gender. No one knows why this happens.

3.  Dietary Habits

Diet seems to play a role in who has twins and who doesn't. Women who eat fatty foods tend to be more likely to have twins. This may be because we need fat to have a healthy pregnancy and those who eat more fat are more prepared to have twins. Fat also affects the reproductive hormones.

There is some research to suggest that it is the common practice of eating yams among Nigerian women that plays a role in their increased risk of having twin pregnancies. Yams are high in phytoestrogens, which are known to increase FSH (follicle-stimulating hormone) levels and result in the release of more than one egg.

4.  Number of Pregnancies

If you have more pregnancies, you have an increased chance of having twins. This could simply be a matter of odds. The more times you are pregnant, the greater are the chances you will have twins.

5.  Mother's Age

It has been established that women who are older are at a greater risk of having fraternal twins. This is because women, especially over the age of 35, make more FSH, increasing their risk of releasing more than one egg. When the FSH level is increasing in this way, the overall fertility level is decreasing. This means that, while you have a lesser chance of getting pregnant, the chances of having twins increases.

6.  Fertility Treatment

If you undergo fertility treatments, your odds of having twins are increased. In particular, if you have IVF, you have a 20-40 percent chance of having twins if more than one embryo is inserted into the uterus. It's possible that IVF also improves your risk of having identical twins, although the research to support that is not clear. In addition, if you take certain fertility drugs, such as Clomid, you increase the chances of having twins because you may release more than one egg at a time. The risk of having more than one baby if you take fertility drugs is between 10 percent and 20 percent.

Since you have known the factors that affect the chances of having twins, you may know what to do to increase the odds. The video below may also help: