Characteristics of pregnancies exposed to opioid analgesics in the first trimester, compared with pregnancies unexposed during the pregnancy period in Ontario, Canada, 2013–2018
| Characteristic | Before weighting | After weighting | ||||
|---|---|---|---|---|---|---|
| No. (%) exposed n = 11 903 | No. (%) unexposed n = 587 676 | Standardized difference | No. (%) exposed | No. (%) unexposed | Standardized difference* | |
| Opioid analgesic use in the year before pregnancy | 5662 (47.6) | 59 108 (10.1) | 0.91 | 3757 (31.6) | 61 941 (10.5) | 0.533 |
| Maternal age at delivery, yr | ||||||
| < 20 | 245 (2.1) | 12 049 (2.1) | 0.001 | 245 (2.1) | 12 047 (2.1) | 0.000 |
| 20–24 | 1502 (12.6) | 60 568 (10.3) | 0.073 | 1459 (12.3) | 61 001 (10.4) | 0.059 |
| 25–29 | 3135 (26.3) | 158 052 (26.9) | 0.013 | 3203 (26.9) | 157 967 (26.9) | 0.001 |
| 30–34 | 4021 (33.8) | 218 741 (37.2) | 0.072 | 4132 (34.7) | 218 263 (37.1) | 0.051 |
| ≥ 35 | 3000 (25.2) | 138 266 (23.5) | 0.039 | 2864 (24.1) | 138 339 (23.5) | 0.012 |
| Year of delivery | ||||||
| 2013 | 2023 (17.0) | 91 418 (15.6) | 0.039 | 1874 (15.7) | 91 384 (15.6) | 0.005 |
| 2014 | 2510 (21.1) | 117 456 (20.0) | 0.027 | 2219 (18.6) | 117 947 (20.1) | 0.036 |
| 2015 | 2505 (21.0) | 117 114 (19.9) | 0.028 | 2426 (20.4) | 117 241 (20.0) | 0.010 |
| 2016 | 2398 (20.2) | 118 223 (20.1) | 0.001 | 2514 (21.1) | 117 947 (20.1) | 0.026 |
| 2017 | 2087 (17.5) | 118 402 (20.1) | 0.067 | 2371 (19.9) | 118 231 (20.1) | 0.004 |
| 2018 | 380 (3.2) | 25 063 (4.3) | 0.057 | 500 (4.2) | 24 976 (4.3) | 0.003 |
| SES quintile at delivery | ||||||
| 1–2 (lowest) | 5863 (49.3) | 250 350 (42.6) | 0.133 | 5118 (43.0) | 251 702 (42.8) | 0.003 |
| 3 | 2394 (20.1) | 120 650 (20.5) | 0.010 | 2406 (20.2) | 120 356 (20.5) | 0.007 |
| 4 | 2131 (17.9) | 120 826 (20.6) | 0.067 | 2422 (20.4) | 120 297 (20.5) | 0.003 |
| 5 (highest) | 1515 (12.7) | 95 909 (16.3) | 0.102 | 1957 (16.4) | 95 321 (16.2) | 0.006 |
| Maternal conditions† | ||||||
| Diabetes | 453 (3.8) | 9446 (1.6) | 0.136 | 312 (1.9) | 14 457 (1.7) | 0.019 |
| Obesity | 571 (4.8) | 14 093 (2.4) | 0.129 | 268 (2.62) | 12 811 (2.5) | 0.010 |
| Hypertension | 482 (4.0) | 12 547 (2.1) | 0.110 | 1383 (2.25) | 60 354 (2.2) | 0.005 |
| Maternal pain diagnosis† | ||||||
| Any | 3131 (26.3) | 57 393 (9.8) | 0.440 | 1383 (11.6) | 603 540 (10.3) | 0.034 |
| Lower back | 2491 (20.9) | 46 146 (7.9) | 0.379 | 1096 (9.2) | 48 601 (8.3) | 0.036 |
| Migraine | 451 (3.8) | 5256 (0.9) | 0.192 | 160 (1.3) | 5642 (1.0) | 0.019 |
| Chronic | 364 (3.1) | 5163 (0.9) | 0.157 | 135 (1.1) | 5524 (0.9) | 0.017 |
| Other | 239 (2.0) | 1897 (0.3) | 0.158 | 58 (0.5) | 2233 (0.4) | 0.004 |
| Limb | 196 (1.6) | 2880 (0.5) | 0.113 | 74 (0.6) | 3467 (0.6) | 0.006 |
| Arthritis | 76 (0.6) | 1617 (0.3) | 0.054 | 30 (0.3) | 1645 (0.3) | 0.002 |
| Facial | 47 (0.4) | 891 (0.2) | 0.047 | 19 (0.2) | 940 (0.2) | 0.003 |
| Elixhauser comorbidity score ≥ 1† | 266 (2.2) | 4083 (0.7) | 0.13 | 105 (0.9) | 4349 (0.7) | 0.016 |
| Previous live birth | 2001 (16.8) | 109 054 (18.6) | 0.05 | 2237 (18.8) | 108 720 (18.5) | 0.007 |
| Other prescribed psychotropic medications‡ | 998 (8.4) | 7934 (1.4) | 0.33 | 480 (4.0) | 8580 (1.5) | 0.158 |
Note: HDPS = high-dimensional propensity scores, NMS = Narcotic Monitoring System, SES = socioeconomic status.
↵* Standardized differences were weighted using inverse probability of treatment weighting with HDPS.
↵† In the year before pregnancy.
↵‡ Data on other prescribed psychotropic medications were available only for barbiturates and benzodiazepines in the NMS database. No exposed pregnant people were prescribed barbiturates; 17 unexposed pregnant people were prescribed barbiturates.