I wouldn't use a particular word, I'd just say, "She can't have a baby."
I would never say something like, "She is infertile/fruitless/barren/sterile .
" – I find that extremely rude.
english.stackexchange.com/users/2237/Sid
Historically, a woman with such a condition was considered to be barren , but that word is not used much today (although it is nevertheless likely to be understood).
Nowadays, one would probably say she is "seeing a fertility counselor" or some such circumlocution, and people would infer the rest.
english.stackexchange.com/users/2303/Robusto
I have always used the word barren , although that word is a bit antiquated.
For some, the word barren may carry a negative connotation.
For instance, when the word is used in the Bible it's written as if it was a curse.
There are Biblical stories of women who were barren but then were blessed by God and were able to conceive.
Consequently, someone who is Jewish/Christian/Muslim might find that particular word a bit insensitive, as it seemingly implies they are cursed.
Perhaps the best way to avoid any potential embarrassment is to state the facts plainly, as in, "She is unable to conceive.
" Even though most people will understand your intent, I'm not a fan of saying, "She cannot have a baby," because that can be taken literally to mean that she is not fit to mother.
Just because someone cannot conceive does not mean they cannot have a child through alternative means, such as adoption or surrogacy.
english.stackexchange.com/users/1631/Scott Mitchell
Joke answers: unbearable, impregnable, inconceivable (maybe that doesn't mean what I think it means...)
english.stackexchange.com/users/None/
In an informal setting, a woman who has passed menopause may describe herself as "dried up" even if she's had many children.
english.stackexchange.com/users/3800/oosterwal
The joke was not meant to provide answers, but a funny lesson on the complexity of the English language - not that other languages aren't complex.
Many lessons are best illustrated through humor - although the underlying lessons of that message can be missed entirely.
Thanks for the go-around here; I was able to give my daughter a lesson in the fun and folly of language.
I personally would say "she was not able to have children", and if that is too difficult just don't bring it up.
I liked the "euphemism treadmill" concept - very illustrative of the situation - I often get dinged for using the words ignorant, or deception as being negative although I find few ways of expressing the same meaning, and both can be positive or neutral when used that way...
english.stackexchange.com/users/None/
"Infertile"; "fruitless"? How would you describe such a woman in an informal talk to your friend?
Is there an informal way to describe a woman that can not have a baby?
english.stackexchange.com
<word-choice><single-word-requests><formality>
english.stackexchange.com/questions/10425
english.stackexchange.com/users/2270/brilliant
It's debatable that you should use a particular word, and you might want to simply say, "She can't have a baby". Terms like "barren" are a bit antiquated and possibly carry a negative connotation. In an informal setting, a woman who has passed menopause may describe herself as "dried up" even if she's had many children. Some would agree that using the direct phrase "she can't have a baby" would suffice, as opposed to using "infertile/fruitless/barren/sterile". But this direct phrase, for others could imply that she is not fit to mother. "Barren" was the term typically used in the past, although the connotation for some might be that they are "cursed".  The term "dried up" was also used by menopausal women  because of their inability to conceive. Today, the direct phraseology could be replaced by "seeing a fertility" counsellor, as there are other ways of conceiving available. 
It's debatable that you should use a particular word, and you might want to simply say, "She can't have a baby". Terms like "barren" are a bit antiquated and possibly carry a negative connotation. In an informal setting, a woman who has passed menopause may describe herself as "dried up" even if she's had many children. Many terms such as barren, infertile or sterile can have negative connotations or be embarrassing, so 'unable to conceive' might be preferred. It might be easier to say something like 'unable to have children' to avoid any connotations of unsuitability.
There are several informal ways to describe someone who can't have a baby including, simply she can't have a baby, or an inference, such as she is seeing a fertility counselor. If after menopause, dried up can be used. Historically barren would have been used, however not so used today. The answer to this question will be a little subjective. Some people will simply prefer to say that "she can't have children" and other would prefer to use an indirect description like "she's seeing a fertility counsellor". There are terms that could be used to describe this concept, such as "barren" or "dried up", but these are likely to be considered offensive.
Just say "she can't have a baby". Some disagree Do not use second phrase Term barren was used in past. Other circumlocutions used today
Many terms such as barren, infertile or sterile can have negative connotations or be embarrassing, so 'unable to conceive' might be preferred. It might be easier to say something like 'unable to have children' to avoid any connotations of unsuitability.
Some people would simply prefer to say that "she can't have children". Terms that might be used ot refer to this might be "barren" or "dried up", but these are likely to be considered offensive. People may want to say that she is "seeing a fertility counsellor" in order to not be too direct.