All About Twins

Yesterday, Today and Tomorrow

If you had told me that I was going to have twins 10 years ago, I would have laughed very hard in disbelief! But, every day more and more soon-to-be moms and dads find out that they have been surprised by the news of twins.

According to the National Center of Health Statistics, the latest numbers (from 2005) show that there were:

• 133,122 twin births


• 6,208 triplet (3 babies) births


• 418 quadruplet (4 babies) births


• 68 quintuplets (5 babies) and other higher order births (6+ babies)

There is definitely a rise in the number of twin and multiple births, especially over the past decade. Since 1980, there has been a 74% increase in the number of multiple births in the US.

As of 2004, there were 32.2 twins per 1,000 total births according to the National Center for Health Statistics. That's a 42% increase from the rate in 1990 of 22.6 twins.

If these numbers continue, which the trend shows that they will, everyone will be able to say that they have or know twins. Multiples keep multiplying!

Why this Increase in Twins?

According to the experts there are many reasons for this new trend in multiple births as well as factors that increase a women's chances of having multiples.

• Increase in the number of women waiting to have their first child. Women over the age of 30 have a naturally higher chance of conceiving twins.


• Increase in the methods and availability of assisted reproductive technology such as IVF


• A maternal family history of multiple births.


• Having twins already.


• People within certain races have a higher incidence of twins than others.


• Consuming a large amount of dairy products! (read up about this in the Journal of Reproductive Medicine link below)

Most people know that there are two types of twins, identical and non-identical (also known as "fraternal").

Identical twins occur when one zygote (or early embryo) divides into two identical zygotes. About a third of twins born are identical and are almost always the same sex (although very rare, boy/girl twins can be identical - see the article in the Journal of Medical Genetics below). Identical twins are also called "monozygotic" (meaning "from one zygote"). Identical twins are identical because they have the exact same DNA.

Some identical twins are considered "mirror twins." Mirror twins are the exact mirror image of each other so that if one has a birthmark on their right cheek, the other will have the same birthmark on their left cheek. This happens in about a quarter of all identical twins.

Fraternal twins occur when two separate eggs are fertilized and grow into zygotes. Fraternal twins are also called "dizygotic" (meaning two zygotes). Fraternal twins are siblings that grow and develop in the mother's womb at the same time, but do not share the exact same DNA. They can be a set of girls (g/g twins), a set of boys (b/b twins) or one of each gender (b/g twins).

Triplets and higher order multiples (4+ babies at the same time) can be either all identical, all fraternal, or a mix of both. However, it is more common to see fraternal multiples in this group.

Conjoined twins, also known as "Siamese Twins," are always identical twins that either didn't properly divide from one another or re-attached to each other again after successfully dividing. In the US, the incidence of this happening is somewhere between 1 in 50,000 to 1 in 200,000.

Well, to answer this question we need to look at your twins. The best place to start is with their gender. Since most b/g twins came from two zygotes, you most likely have fraternal twins.

Things get a little more complicated when you have g/g and b/b twins. First take a look at your twins - do you think they look identical? If you think they do, the best way to determine if they are truly identical is to have their DNA tested. There are several companies that will do this for you which your pediatrician can recommend.

If your g/g twins or b/b twins do not look similar, then most likely you have fraternal twins, but they may be mirror twins which may give them the appearance of being dis-similiar. It may be a good idea to get tested just to be certain.

Of course, you may not even be interested in knowing what kind of twins you have and that's okay too.

I have b/g fraternal twins. Do you think they look identical in the picture above?

Some Celebrities That Have Twin Children

Chuck Norris

Angelina Jolie and Brad Pitt

Jennifer Lopez

Marcia Gay Harden

Holly Robinson Peete

Cleopatra

Laura Bush

Julia Roberts

Mia Hamm

Joan Lunden

Denzel Washington

Sean Combs

Some Celebrities That Have A Twin Sibling

Alanis Morissette

Ashton Kutcher

Billy Dee Williams

Joseph Fiennes

Justin Timberlake

Kiefer Sutherland

Mario Andretti

Mary-Kate and Ashley Olsen

Scarlett Johansson

Vin Diesel