this may be a stupid question and a myth that parents made up to deter steroid use, but after reading the thread about clubbing and having kids while wearing a shiny shirt; i was wondering if steroids can/do cause birth defects?
I was wondering the same as my wife and I are trying also. Not saying that a lot of NFL players use steroids but it sure seems that a lot of their kids have birth defects.
There is no evidence that steroids cause birth defects. There is circumstantial evidence that steroid use makes it more likely for you to have a daughter than a son, which I would consider a defect - cause who wants a daughter? 
The only thing that aas affects is your sperm count, which is greatly reduced.
I’ve heard of doctors or parents trying to blame a troublesome kid on steroid/drug use, but I tend to think it’s simply irresponsible to do so.
In short, if you knock your girl up while juicing, don’t worry. If you’re trying to conceive, it’s better to be safe than sorry, not to mention you count will be low, so it’s harder anyway.
Like Merlin said.
If you’re able to impregnate, you’re probably okay. Birth Defects can be induced if you are using transdermal steroids however, as they can readily transfer to another person (like a pregnant wife, or a child).
of course we are talking in the context of the father being the user, not the mother. i am also trying with my lovely mate and i asked my doc this question point blank. she didnt hesistate in saying absolutely no chance. my doc said the transfer of chemical through our body fluids wouldnt be enough to show on even the most sensative test. it is a minute amount. she said that birth defects are most commonly genetic and these genes are not altered by steroid use.
Zero chance. Only possible thing I can think of is if you were doing transdermal testosterone, which was transfered to the mother through physical contact while she was pregnant, or the child having physical contact with you(such as holding them). But this is a long shot and not very likely.