Winning a large lottery prize increases the likelihood that single men marry, while raising the short-term likelihood of divorce for married women. The analysis said the impact of a sudden financial cushion on marriage, divorce and childbirth can vary by gender and income level.

Japanese media outlet Gigazine reported on Nov. 13 that a joint research team including New York University and Stockholm University published findings based on an analysis of 76,859 Swedish lottery buyers. The results were published in the international academic journal Journal of Human Resources.

The researchers compared people who bought the same lottery but received different prize amounts. They tracked marriage, divorce and childbirth records for up to 10 years for participants who were aged 18 to 44 at the time of winning, analysing how unexpected income increases affected family relationships.

The results showed that among single men, a post-tax increase of 1 million Swedish crowns in winnings raised the probability of marrying within five years by 4.7 percentage points. Based on a baseline marriage probability of 16 percent, that would rise to about 20.7 percent. The effect was concentrated among men whose pre-win income was below the median.

By contrast, no statistically significant change was confirmed in the marriage probability of single women. The gender difference itself was also not at a level that could be statistically confirmed.

Differences were more pronounced in divorce. Among married women, a 1 million crown increase in winnings lifted the probability of divorcing within two years to about 8 percent from about 4 percent. The pattern was particularly clear among women with low pre-win income.

However, an increase in divorce probability was not confirmed after 10 years. The researchers suggested that a large win may have helped women who were already planning to end their marriage become economically independent, bringing forward the timing of divorce rather than triggering new divorces.

Some impact was also seen in childbirth. For men, each 1 million crowns in winnings led to an average of 0.056 more children over 10 years, raising the birth rate by about 14 percent. The increase effect for women was not statistically significant.

The researchers assessed that financial support can affect family formation, but that its cost-effectiveness as a policy tool to raise birth rates is limited.

Because the study focused on Sweden, where welfare systems are developed and legal barriers to divorce are low, it is difficult to conclude that the same results will appear in other countries.