(MONEY Magazine) – Prenuptial agreements were once used primarily by very rich individuals who wanted to protect their assets from their spouses if they ever divorced. But lately, premarital pacts have become more popular with middle-income couples, thanks in part to a divorce rate of nearly 50% and the advent of state equitable-distribution laws that dictate how property is divided when a marriage dissolves. (Premarital contracts supersede such laws.) For the same reasons, postnuptial agreements are becoming more common as well. Last month's blizzard of publicity about Ivana Trump's attempt to invalidate her paper deal -- worth $25 million and a 45-room mansion in Greenwich, Conn. -- with The Donald has raised questions, however, about whether prenups are worth the bother. Here are some answers from family law experts: Should you have one? If you and your fiance are starting out with roughly similar assets, maybe not. But the contracts are well suited to people with children from previous marriages or for people marrying late in life who would not want a divorce to prevent them from leaving a sizable inheritance to their families. Also, a couple can use an agreement to provide for post-split compensation to the partner who put the other through school or abandoned a career to raise the kids. There are also situations in which a married couple might want a postnuptial pact -- if, for example, one of them gets a huge inheritance. How much do they cost? Total legal fees run from $500 to several thousand dollars, depending on the complexity of the contract. The prospective husband and wife should have different lawyers to avoid conflicts of interest. How can you make sure yours will hold up? Experts say the key is to disclose % all your holdings to each other in writing and to sign your agreement in front of a notary and a witness. You can make the agreement even stronger by concluding it two months or so before the wedding; conceivably, a person who signed a document at the last minute could claim that he or she was under duress -- which can be grounds for unsticking a deal. Still, attorney Joseph Zwack of Dubuque, Iowa, author of Premarital Agreements: When, Why & How to Write Them (Harper & Row, $7.95), says that of the 10% or fewer that are ever challenged in court, ''a very high percentage survive intact.'' Are there other drawbacks? Discussing an accord to take effect in the event of discord is hardly romantic. As marital lawyer Raoul Felder says, ''You're negotiating a divorce'' in advance. But attorney Jacalyn F. Barnett, the head of the matrimonial department at New York City law firm Shea & Gould, says: ''Why shouldn't you arrange your affairs the way you both want them, instead of how the state decrees?''