hi, ive read on here some peoples views on how old a bitch should be to have a first litter. im just wondering why people  think a bitch should have had a first litter by a certain age? health reasons? or other?
thanks

Health reasons. As in humans the risks with a first baby/litter become greater the older the mother. IMO the best age for a first litter is 3 years old; not before 2 and not after 5.

the reason i ask is that in the future i would like to breed from my gsd bitch. if i did go ahead my thinking was that i would breed in two ish years (she would have just turned 4) and someone made a comment that it was too old.

I would specifically ask fellow breeders, exhibitors , or working freinds what their opinion is. 

People will give opinions based on "their" breed but it varies greatly from breed to breed also.

Is she hipscored?

not as yet-obviously i would never consider breeding if she had poor hip or elbow scores- its just a possibility for the future.

I don't consider 4 old.  My bitch had her first litter at 5 and a second aged 7.  If they are fit and healthy that helps, a bitch could be 2, flabby and untoned and have a dreadful time whelping whereas a 4-5 year old, muscular & toned could pop them out like peas.

well shes extremely fit, as i said earlier i compete with her. i didnt think 4 was old its just someone on here said it is too old for a first litter. thanks for your advice.
p.s. i only plan on having the one litter from her.

Also I find that the maternal instincts weaken with leaving the first litter until longer.