There's a whole host of things that couples should discuss before making a life-long commitment: finances, housing, employment, health insurance, etc. But the decision to have -- or not have -- children should be at the top of that list.

On Monday, Reddit user fightlikehell, who doesn't want children, posted some concerns on the forum-based site after her fiance -- who previously agreed that the couple wouldn't have children -- hinted at the possibility of a baby one day. Though she talked with him prior to the engagement about not having kids, she's worried that he wants to go back on the agreement.

Other Redditors offered advice, suggesting the user should have a friend ask him about his true thoughts, or talk to him about a plan for telling those who ask about their decision to remain child-free.

Discussing whether or not to have children before getting hitched is a must, according to relationship expert and author of "Marriage Rules" Harriet Lerner. HuffPost asked Lerner how the Redditor could best handle her situation.

When should couples start talking about having -- or not having -- children?

As soon as one person in the couple is thinking about the other as a prospective mate.

How long before a marriage should the issue be settled?

The sooner the issue is discussed openly, the better. Also, it may take many conversations for people to deepen and refine the truths they tell to each other -- or even tell to themselves. Keep the lines of communication open and revisit the issue for as long as necessary.

What should a couple do if one partner wants children and the other doesn't?

The party who wants children needs to get clear about whether the wish for a child is greater than the wish for the relationship -- or vice versa. Where one lands on this difficult question determines whether one walks -- or, alternatively, moves forward with their partner understanding the sacrifice involved.

In the case of the Redditor, should she confront her fiance and solidify their wants as a couple before the marriage? How should she go about doing that?

"Confrontation" may not be the right word, because it implies a negative or intense conversational tone, which won't widen the path for truth-telling and mutual understanding Her challenge is to talk to her fiance as openly as possible, and ask him questions that will help clarify his feelings and voice his doubts on the subject. It may take a number of conversations before he may something like, "Right now I picture our life together as child-free, but I can't promise that my feelings won't change five years down the road."

If a partner changes his or her mind about children, how do they bring it up with their significant other?

One brings it up, as one would bring up any difficult or emotionally-loaded question: clearly, without mystification, and at a calm time when the other person is most able to take in the difficult information. Several conversations are more useful than one marathon conversation.

In these kinds of cases, is "birth control sabotage" common?

While I wouldn't say it's "common," more than a few women have poked holes in their diaphragm (or the contraceptive equivalent thereof) in the hope that their partner would soften when there was a live little person tugging at his sleeve. This turnabout can happen. The "No" partner may indeed fall madly in love with the baby and undergo a major transformation that would void all previous negotiations. That said, I strongly advise against such radical deception. It’s a terribly unfair gamble that puts three people at risk.

How should couples resolve differences regarding having children? (i.e. can there be a compromise between couples?)

Clearly, couples should discuss and negotiate the baby question (and all other pivotal issues) before making a serious commitment, although there is no guarantee that one person's feelings won't change later on.

When one person desperately wants a child and the other desperately doesn't, the situation can't be handled by compromise. I've seen people try it, and it doesn't work. For example, one married woman, suddenly eager to have the child she thought she'd never want, promised her husband that she would take total care of it herself; she even presented him with a contract vowing that he would never have to change a diaper, cart the child to a pediatrician, or do anything to raise it. She only wanted his economic support. This is a proposal that might work with a pet parrot, where she could feed it, clean the cage, and take it to the vet while her husband simply paid the bills. But it's not a viable arrangement when it comes to having a child. Single parents, can, indeed, raise children well on their own; married partners with able-bodied live-in partners do not. The question at hand is not one that lends itself to compromise.