1~800 births (approximately)
Better odds than the lottery huh?
Every person is made up of chromosomes, we all have 46 chromosomes. 23 from mom and 23 from dad. A person with Down syndrome has 47. They have that extra little chromosome 21.
Trisomy 21 about 95% of the time, Down syndrome is caused by trisomy 21-the child has 3 copies of chromosome 21 (instead of the usual 2 copies) in all cells.
This is caused by abnormal cell division during the development of the Sperm cell or the egg cell.
Mosaic Down syndrome. In this rare form of Down syndrome, children have some cells with an extra copy of chromosome 21. This mosaic of normal and abnormal cells is caused by abnormal cell division after fertilization.
Translocation Down syndrome. Down syndrome can also occur when part of chromosome 21 becomes attached (translocated) into another chromosome, before or at conception. These children have the usual two copies of chromosome 21,but they also have additional material from chromosome 21 attached to the translocated chromosome.
There is no known behavioral or environmental factors that cause Down syndrome.
With that being said, there is nothing a mom done during pregnancy that could/would cause a child to have Down syndrome.
Here is what didn't cause Down syndrome.
Not taking vitimans
No pre-natal care
Smoking
Drugs
Drinking
Health
Nutritional
Environment
Behavior
Medication
Abuse
Age
(Most of them are not good choices but, it didn't cause your child to have Down syndrome.)
Here is what causes Down syndrome.. Abnormal cell division during conception.
An extra copy of chromosome 21!! Simple! That's it just 1 thing.
Over 90% of babies are aborted when they have a prenatal diagnosis of Down syndrome. (Mainly Due to lack of up to date information)
Older moms have a higher % rate of having a child with Down syndrome, yet a young mom at 18 can have a child with Down syndrome.
Characteristics are but not limited to
Those cute little almond eyes
A gap between the big toe and 2nd toe
(Also known as sandle gap)
A single palm crease in the hands.
Short statue
Small nose
Lower set ears
Children with Ds can do all things "typical" kids can do (they just do it in thier own time frame) no hurry
If you or someone you know just got a prenatal diagnosis or are a new mom to a child with Down syndrome, I won't paint you a rainbow and butterflies picture. The doctors appointments are many in the beginning but it slows down I promise.
The therapy will be harder on you than them.
Every little thing will make you worry more than with a "typical" child (that's ok) we are moms we are suppose to worry right?
You can and will make it!! This child will teach you love, patience, understanding and open your eyes to a part of life you never knew existed.
You don't have to be super mom just be the best mom you can and that's super!
And if someone ask "how do you do it" "how do you raise a child with Down syndrome?
I'm a mom! I do what I gotta do! Full mommy mode kicks in. 
