Objective: Male live births slightly exceed female live births by approximately 3%. The ratio of male to total live births is conventionally represented as M/F. Many factors have been shown to affect M/F, mainly privation, toxins, and stress, all of which reduce M/F. Population stress may be engendered by natural phenomena such as earthquakes and man-made events such as short wars, terrorist attacks, and contracting economies. This study was conducted to ascertain whether the onset of the "Great Recession" (2007) was associated with changes in M/F in the United States (US).

Material and methods: Annual monthly live births by gender for January 2006 to December 2008 were obtained from United States Centres for Disease Control and Prevention.

Results: In 2007, there were 4316233 live births [M/F: 0.51157; 95% confidence intervals: 0.51110-0.51205). M/F rose between January and June, and then fell sharply between August and December. M/F was statistically significantly lower in the second half of 2007 (p=0.007). The dip in M/F from June to July was also significant (p=0.02). These findings were not replicated in the amalgamated data for 2006 and 2008.

Conclusion: The United States housing boom of the mid-2000s was fueled by rising house prices and cheap mortgages given to credit-poor buyers. A halt in rising house prices resulted in defaults and foreclosures, triggering the worst financial crisis since the Great Depression. The associated stress appears to have decreased M/F in the US.