In the USA couples who are childless experience a 66 percent divorce rate, compared to 40 percent among couples with children.
Having a child can add an extra layer of commitment to a relationship. However children do make the divorce process complicated and messy, so therefore it is "simpler" to get a divorce without children.
The article fails to mention what classifies as "childless". Is it marriages that have no kids at all, or are empty-nesters included? If empty-nesters are not included and are part of the have children category, we do know there is a spike in divorces when all of the children leave the home. So in this case, having children in general is not the super glue that keeps a marriage together.
We also can't discount the value system of marriages without children. The reasoning for not having kids is economical, in that they cost too much. These marriages tend to be for socioeconomic status. So there could be a peak in these type of couples having a divorce due to the recession. In the sense that it may be more economical to be single, instead of paying for an unemployed spouse.
However, have a read of the article here.
Also, check out 21 factors that increase ones risk for divorce.