How do you tell the difference between male and female rats when they are born?

i have 13 rats, 2 days old. how do i tell difference between gender?How do you tell the difference between male and female rats when they are born?
The easiest way to tell is by looking at the spacing between the anus and the urethra. Males will have more space between the anus and the urethra, than females.





It may be a little difficult to tell them apart just yet(unless you know what you are looking for). It gets much easier in about a week, when it is very clear by the spacing.





Here is a link with pictures


http://www.afrma.org/sexing101.htmHow do you tell the difference between male and female rats when they are born?
If the mom will let you, it's actually a good thing to handle them. This gets them used to human contact, which is a good thing. On female ratties, the space between the vagina, and the anus is much shorter than the space between the penis and the anus. Also, if you look carefully, you may be able to see nipples on the females.





Also! Check for Milk bands on their tummys to make sure they are eating well.
It is too hard to tell at this age, and you shouldn't be handling the newborns. Wait until they are older.