Yes and no.
If you are wealthy (and I mean really wealthy) and she is not, AND you have no children-EVER-a prenup is a good idea.
Once you have a child, the courts will use "child support" to take anything that they cannot get from "alimony", and prenups with regard to child custody and support are almost never found valid.
HTH.
Short answer: sometimes. But don't bet on it
I posted on another thread Men Behaving Badly - Why?:
You are mostly right, but the law of supply and demand means that men can make demands prior to getting married, such as requiring a prenuptial agreement, requiring that the prospective spouse be debt-free etc.Prenups are mainly for the case where both parties come into the marriage with assets, and the husband needs to ensure that his assets go to his kids from prior marriage, instead of new wife. Do NOT count on a prenup being enforcible against a wife if you have significant assets and a well-paying job. The courts will probably not enforce any contract that would make some irate feminist columnist upsetThis assumes that the prenup gets enforced. The courts may decide to enforce it, or may disregard it as "against public policy". See here. Also, provisions regarding child support are prohibited (see here) and any prenup which would "provide a standard of living far below that which was enjoyed before the marriage" will also be unenforcable (see prior link). Also, it may be cancelled if one party "signed under duress" (here), where "duress" may be found to include "sign this or I won't marry you"
Bottom line: a prenup may not be enforcible against her, but certainly WILL be enforced against YOU