Risk of preterm and early term birth by maternal drug use.

Objective: Examine the risk of preterm birth (PTB, < 37 weeks) and early term birth (37-38 weeks) for women with reported drug abuse/dependence.
Study Design: The population was drawn from singleton livebirths in California from 2007 to 2012. Drug abuse/dependence was determined from maternal diagnostic codes (opioid, cocaine, cannabis, amphetamine, other, or polysubstance). Relative risks, adjusted for maternal factors were calculated for PTB and early term birth.
Result: Of the 2,890,555 women in the sample, 1.7% (n = 48,133) had a diagnostic code for drug abuse/dependence. The percentage of PTBs varied from 11.6% (cannabis) to 24.3% (cocaine), compared with 6.7% of women without reported drug abuse/dependence.
Conclusion: Women with reported drug abuse/dependence during pregnancy were at increased risk of having a PTB and all but those using cannabis were at risk of having an early term birth. Women using cocaine and polysubstance were at the highest risk of birth < 32 weeks.