A mathematical analysis of data from 5,574 couples who first married between 1979 and 2010 and had children has shown that when a child was conceived within the marriage, the chance that the couple would divorce was substantially lower. Conversely, when couples conceived a child before they were married, divorce was more likely.
A team of researchers, including José Alberto Molina from the University of Zaragoza in Spain, examined data from the American National Longitudinal Survey of Youth 1979, which interviewed 12,686 young people every year between 1979 and 1994, and every two years (in even-numbered years) since then.
The challenge was to distinguish the causal effect of conceiving children before and after marriage from an effect in the other way direction: namely, happier couples may be both less likely to divorce and more likely to have more children. The researchers dealt with this problem by using a statistical approach which identifies variables that might affect how many children a couple will have but not their propensity to divorce.
The research team offers an economic explanation for its findings: individuals divorce if their expected gains from marriage fall short of their expected utility outside the current marriage. The presence of children conceived within the marriage increases the value of the marriage, more so than the disruptive effect that children are known to have on many couple relationships. The effect of children conceived before and within marriage is different because they may be valued differently by their parents–parents who conceive children within marriage can be expected to place more value on the institution of marriage, and may therefore place more value on marital investments such as children. Thus the disruptive effect of children conceived before marriage is higher.
Bellido H, Molina JA, Solaz A & Stancanelli E (2016), Do children of the first marriage deter divorce? Economic Modelling 55