Table 2. Adjusted Prevalence of Cannabis Use During Early Pregnancy in Kaiser Permanente Northern California for Each Year (2009-2018) and Annual Relative Rate of Change, by Polysubstance Use (N = 367 138).
| Substance use | Adjusted prevalence of cannabis and co-occurring substance use during pregnancy, % (95% CI)a | Linear trend estimation | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | Annual relative rate of change estimate (95% CI) | P value | ||
| No. of co-occurring substances | |||||||||||||
| Cannabis only | 2.39 (2.20-2.58) | 2.87 (2.65-3.08) | 3.23 (3.00-3.46) | 3.34 (3.11-3.57) | 3.63 (3.38-3.87) | 4.24 (3.99-4.50) | 4.70 (4.43-4.97) | 5.11 (4.84-5.39) | 5.87 (5.57-6.16) | 6.30 (6.00-6.60) | 1.11 (1.10-1.12) | <.001 | |
| Annual relative rate | NA | 1.20 (1.07-1.34) | 1.13 (1.02-1.25) | 1.03 (0.94-1.14) | 1.08 (0.99-1.19) | 1.17 (1.07-1.28) | 1.11 (1.02-1.20) | 1.09 (1.01-1.18) | 1.15 (1.07-1.23) | 1.07 (1.00-1.15) | |||
| Cannabis and 1 other substance | 1.19 (1.07-1.32) | 1.16 (1.03-1.28) | 1.27 (1.14-1.40) | 1.28 (1.15-1.42) | 1.30 (1.16-1.43) | 1.30 (1.17-1.43) | 1.31 (1.18-1.44) | 1.28 (1.16-1.41) | 1.47 (1.33-1.60) | 1.92 (1.77-2.07) | 1.04 (1.03-1.05) | <.001 | |
| Annual relative rate | NA | 0.97 (0.83-1.13) | 1.10 (0.95-1.28) | 1.01 (0.87-1.17) | 1.01 (0.87-1.17) | 1.00 (0.87-1.16) | 1.01 (0.87-1.16) | 0.98 (0.85-1.13) | 1.15 (1.00-1.31) | 1.31 (1.16-1.48) | |||
| Cannabis and ≥2 other substances | 0.56 (0.48-0.64) | 0.53 (0.45-0.60) | 0.56 (0.48-0.64) | 0.53 (0.46-0.61) | 0.45 (0.38-0.53) | 0.44 (0.37-0.51) | 0.43 (0.36-0.49) | 0.41 (0.35-0.48) | 0.43 (0.36-0.50) | 0.50 (0.43-0.57) | 0.97 (0.96-0.99) | <.001 | |
| Annual relative rate | NA | 0.94 (0.77-1.15) | 1.06 (0.86-1.29) | 0.95 (0.78-1.17) | 0.85 (0.69-1.06) | 0.96 (0.77-1.20) | 0.97 (0.78-1.22) | 0.97 (0.78-1.21) | 1.04 (0.84-1.30) | 1.16 (0.94-1.43) | |||
| Type of co-occurring substance use | |||||||||||||
| Cannabis only | 2.39 (2.20-2.58) | 2.87 (2.65-3.08) | 3.23 (3.00-3.46) | 3.34 (3.11-3.57) | 3.63 (3.38-3.87) | 4.24 (3.99-4.50) | 4.70 (4.43-4.97) | 5.11 (4.84-5.39) | 5.87 (5.57-6.16) | 6.30 (6.00-6.60) | 1.11 (1.10-1.12) | <.001 | |
| Annual relative rate | NA | 1.20 (1.07-1.34) | 1.13 (1.02-1.25) | 1.03 (0.94-1.14) | 1.08 (0.99-1.19) | 1.17 (1.07-1.28) | 1.11 (1.02-1.20) | 1.09 (1.01-1.18) | 1.15 (1.07-1.23) | 1.07 (1.00-1.15) | |||
| Cannabis and alcohol | 1.11 (0.99-1.23) | 1.08 (0.96-1.21) | 1.14 (1.01-1.27) | 1.16 (1.03-1.28) | 1.13 (1.01-1.26) | 1.12 (0.99-1.24) | 1.10 (0.98-1.22) | 1.07 (0.96-1.19) | 1.35 (1.22-1.48) | 1.87 (1.73-2.02) | 1.04 (1.03-1.06) | <.001 | |
| Annual relative rate | NA | 0.97 (0.83-1.14) | 1.05 (0.90-1.23) | 1.02 (0.87-1.19) | 0.98 (0.84-1.14) | 0.99 (0.84-1.15) | 0.99 (0.85-1.15) | 0.97 (0.84-1.13) | 1.26 (1.09-1.45) | 1.39 (1.23-1.57) | |||
| Cannabis and nicotine | 1.05 (0.93-1.16) | 0.97 (0.86-1.09) | 1.05 (0.93-1.17) | 0.99 (0.88-1.11) | 0.90 (0.79-1.01) | 0.88 (0.77-0.98) | 0.85 (0.74-0.95) | 0.84 (0.74-0.94) | 0.78 (0.68-0.88) | 0.83 (0.73-0.92) | 0.97 (0.96-0.98) | <.001 | |
| Annual relative rate | NA | 0.93 (0.79-1.09) | 1.07 (0.91-1.26) | 0.95 (0.81-1.11) | 0.91 (0.77-1.07) | 0.98 (0.82-1.16) | 0.96 (0.81-1.15) | 0.99 (0.84-1.18) | 0.93 (0.78-1.10) | 1.06 (0.89-1.26) | |||
| Cannabis and pharmaceutical opioids | 0.08 (0.06-0.10) | 0.06 (0.04-0.08) | 0.07 (0.05-0.09) | 0.08 (0.06-0.10) | 0.09 (0.07-0.11) | 0.09 (0.07-0.11) | 0.10 (0.08-0.12) | 0.07 (0.06-0.09) | 0.07 (0.05-0.08) | 0.07 (0.05-0.08) | 1.00 (0.97-1.03) | .95 | |
| Annual relative rate | NA | 0.81 (0.56-1.19) | 1.15 (0.78-1.70) | 1.08 (0.75-1.56) | 1.16 (0.82-1.63) | 0.95 (0.68-1.32) | 1.20 (0.88-1.64) | 0.73 (0.53-1.00) | 0.91 (0.64-1.28) | 0.97 (0.68-1.38) | |||
| Cannabis and stimulants | 0.16 (0.12-0.20) | 0.15 (0.11-0.18) | 0.20 (0.16-0.24) | 0.17 (0.13-0.21) | 0.15 (0.11-0.19) | 0.18 (0.14-0.21) | 0.18 (0.14-0.22) | 0.18 (0.14-0.22) | 0.20 (0.16-0.24) | 0.23 (0.18-0.27) | 1.03 (1.01-1.06) | .01 | |
| Annual relative rate | NA | 0.90 (0.65-1.26) | 1.37 (0.99-1.88) | 0.84 (0.62-1.14) | 0.90 (0.65-1.26) | 1.16 (0.84-1.61) | 1.04 (0.77-1.41) | 0.98 (0.73-1.32) | 1.10 (0.82-1.47) | 1.15 (0.87-1.51) | |||
a
Adjusted prevalence estimates and 95% CIs were estimated from Poisson regression models controlling for age group, race and ethnicity, and median neighborhood household income (extracted from the electronic health record).