Housing and Fertility

 A study on housing and fertility. I should mention that this is in Brazil.

We find that obtaining housing increases the average probability of having a child by 3.8% and the number of children by 3.2%. For 20-25-year-olds, the corresponding effects are 32% and 33%, with no increase in fertility for people above age 40. The lifetime fertility increase for a 20-year old is twice as large from obtaining housing immediately relative to obtaining it at age 30. The increase in fertility is stronger for households in areas with lower quality housing, greater rental expenses relative to income, and those with lower household income and lower female income share. These results suggest that alleviating housing credit and physical space constraints can significantly increase fertility. 

Housing for family formation has frequently been put forward as a key item, and verticality is supposed to depress birthrates in cities worldwide.  Cities themselves depress birthrates anyway, and have for centuries.