[clavalle]

*When not taking into account prematurely born children, which among crack users is 17–27% compared to between 3-4% for the population at large.

[smsm42]

How do we know it is caused by crack use and not by other factors that usually correlate with heavy crack use?

[clavalle]

Because in areas with high poverty but low-cocaine use rates the pre-term birth rate rises (from 3.9% to 4.9%) but not as much as among crack-cocaine users (17%-29%).