Table 2.
Maternal Report and Testing Results for Smoking and Drug Use by Stillbirth Collaborative Research Network Case Status
| Characteristic - Weighted %* | Stillbirth | Live Birth | Odds Ratio (95% CI) | P |
|---|---|---|---|---|
| Maternal report of smoking | ||||
| Unweighted sample size – n = | 613 | 1,832 | ||
| Weighted sample size – nw = | 614 | 1,366 | ||
| Smoked trimester the baby was born (%) | ||||
| No, never smoked | 81.1 | 87.1 | Reference | 0.002 |
| No, smoked previously† | 8.8 | 7.2 | 1.31 (0.92, 1.86) | |
| Yes, 1–9 cigarettes/day on average | 5.9 | 3.6 | 1.77 (1.13, 2.80) | |
| Yes, 10+ cigarettes/day on average | 4.2 | 2.1 | 2.17 (1.25, 3.78) | |
| Test: linear trend | 0.003 | |||
| Cotinine testing | ||||
| Unweighted sample size – n | 579 | 1,545 | ||
| Weighted sample size – nw | 576 | 1,183 | ||
| Positive for Cotinine (%) | 18.5 | 9.3 | 2.22 (1.67, 2.95) | <.001 |
| Cotinine concentration (ng/ml) (%) | ||||
| Negative (<0.25)‡ | 81.5 | 90.7 | Reference | <.001 |
| Positive, <3 | 6.4 | 3.3 | 2.16 (1.39, 3.37) | |
| Positive, 3+ | 12.1 | 6.0 | 2.25 (1.59, 3.19) | |
| Test: linear trend | <.001 | |||
| Cotinine concentration (ng/ml), by quartile for positives (%) | ||||
| Negative (<0.25)‡ | 81.5 | 90.7 | Reference | <.001 |
| Positive, ≤1.49 | 4.8 | 2.3 | 2.36 (1.40, 3.97) | |
| Positive, 1.49 – 9.68 | 3.5 | 2.3 | 1.73 (0.99, 3.03) | |
| Positive, 9.68 – 23.62 | 4.1 | 2.4 | 1.96 (1.10, 3.47) | |
| Positive, >23.62 | 6.0 | 2.4 | 2.81 (1.69, 4.67) | |
| Test: linear trend | 0.004 | |||
| Cotinine concentration (ng/ml), by median for positives (%) | ||||
| Negative (<0.25)‡ | 81.5 | 90.7 | Reference | <.001 |
| Positive, ≤ 50th %tile (≤9.68) | 8.4 | 4.5 | 2.04 (1.39, 3.01) | |
| Positive, > 50th %tile (>9.68) | 10.1 | 4.7 | 2.39 (1.62, 3.52) | |
| Test: linear trend | <.001 | |||
| Maternal report of smoking and cotinine testing | ||||
| Unweighted sample size – n | 548 | 1,489 | ||
| Weighted sample size – nw | 546 | 1,144 | ||
| Cotinine and smoking during the trimester the baby was born (%) |
|
|||
| Negative cotinine (<0.25)‡ & never smoked | 75.8 | 84.5 | Reference | |
| Negative cotinine (<0.25)‡ & smoked previously† | 5.3 | 5.6 | 1.04 (0.66, 1.65) | |
| Negative cotinine (<0.25)‡ & smoked | 0.5 | 0.8 | 0.73 (0.20, 2.72) | |
| Positive cotinine, <3 ng/ml, & did not smoke | 5.0 | 2.7 | 2.06 (1.24, 3.41) | |
| Positive cotinine, 3+ ng/ml, & did not smoke | 3.6 | 1.5 | 2.61 (1.39, 4.88) | |
| Positive cotinine, any concentration, & smoked | 9.8 | 4.8 | 2.30 (1.54, 3.43) | |
| Cotinine and smoking during the trimester the baby was born (%) | ||||
| Negative cotinine (<0.25)‡ & never smoked | 75.8 | 84.5 | Reference | <.001 |
| Negative cotinine (<0.25)‡ & smoked previously† | 5.3 | 5.6 | 1.04 (0.66, 1.65) | |
| Negative cotinine (<0.25)‡ & smoked | 0.5 | 0.8 | 0.73 (0.20, 2.72) | |
| Positive cotinine, ≤ 50th %tile (≤9.68 ng/ml), & did not smoke | 5.9 | 3.5 | 1.89 (1.19, 3.00) | |
| Positive cotinine, > 50th %tile (>9.68 ng/ml), & did not smoke | 2.7 | 0.8 | 3.84 (1.74, 8.46) | |
| Maternal report of lifetime drug use | ||||
| Unweighted sample size – n | 611 | 1,823 | ||
| Weighted sample size – nw | 610 | 1,349 | ||
| Lifetime drug use(%) | ||||
| Reported never used drugs | 67.2 | 69.3 | Reference | 0.007 |
| Reported drug use | ||||
| Without addiction | 28.1 | 28.6 | 1.01 (0.81, 1.26) | |
| With addiction | 4.7 | 2.1 | 2.30 (1.37, 3.86) | |
| Toxicology screening§ | ||||
| Unweighted sample size – n | 418 | 1,050 | ||
| Weighted sample size – nw | 405 | 874 | ||
| Positive for any drug (%) | 7.0 | 3.7 | 1.94 (1.16, 3.27) | 0.012 |
| Positive for specific drugs (%) | ||||
| Morphine | 1.3 | 0.4 | 3.46 (0.86, 13.90) | 0.080 |
| Hydromorphone | 0.0 | 0.0 | — | — |
| Codeine | 0.6 | 0.2 | 2.80 (0.39, 20.27) | 0.307 |
| Hydrocodone | 0.4 | 0.0 | 152.57 (13.73, 1695.65) | <.001 |
| Pethidine / Meperidine | 0.0 | 1.0 | — | — |
| THCA (Tetrahydrocannabinolic acid) | 3.9 | 1.7 | 2.34 (1.13, 4.81) | 0.021 |
| Cocaine (Benzoylecgonine) | 0.9 | 0.6 | 1.59 (0.41, 6.14) | 0.501 |
| Amphetamine or Methamphetamine | 0.7 | 0.1 | 8.17 (0.84, 79.68) | 0.071 |
| None, single or multiple drugs detected (%) | ||||
| Negative for all drugs | 93.0 | 96.3 | Reference | 0.033 |
| Positive for 1 drug | 6.2 | 3.5 | 1.83 (1.06, 3.15) | |
| Positive for 2 drugs | 0.8 | 0.2 | 3.69 (0.64, 21.31) | |
| Maternal report of lifetime drug use and toxicology screening | ||||
| Unweighted sample size – n | 384 | 980 | ||
| Weighted sample size – nw | 373 | 813 | ||
| Umbilical cord toxicology and lifetime drug use (%) | ||||
| Negative for all drugs & reported never used drugs | 64.8 | 68.4 | Reference | 0.023 |
| Negative for all drugs & reported drug use | 28.3 | 28.2 | 1.06 (0.80, 1.41) | |
| Positive for any drug & reported never used drugs | 2.1 | 1.9 | 1.19 (0.50, 2.84) | |
| Positive for any drug & reported drug use | 4.8 | 1.5 | 3.30 (1.54, 7.03) | |
| Cotinine testing and toxicology screening | ||||
| Unweighted sample size – n | 380 | 891 | ||
| Weighted sample size – nw | 367 | 742 | ||
| Cotinine and drug use (%) | ||||
| Negative cotinine (<0.25)‡ & negative for all drugs | 80.6 | 88.6 | Reference | 0.001 |
| Positive cotinine & negative for all drugs | 12.4 | 8.0 | 1.70 (1.13, 2.56) | |
| Negative cotinine (<0.25)‡ & positive for any drug | 3.3 | 2.4 | 1.53 (0.71, 3.27) | |
| Positive cotinine & positive for any drug | 3.8 | 1.1 | 3.86 (1.61, 9.24) | |
CI, confidence interval.
Weighted percentages, odds ratios and p-values are shown. The weights take into account the study design and differential consent based on characteristics recorded on all eligible pregnancies that were screened for the study. Unweighted and weighted samples sizes are also provided. The weighted sample sizes are not integers, but are shown rounded to the nearest integer. For ordered categories on smoking history in the trimester the baby was born and cotinine levels, tests for linear and quadratic trends in the log odds of stillbirth were conducted using orthogonal contrasts. None of the quadratic trends was significant and their p-values are not reported. Nw is a count of the observations according to their relative weight in the analysis.
‘Previously’ indicates that the mother reported smoking 3 months prior to pregnancy or during pregnancy, but not during the trimester the baby was born.
Lower limit of detectability for the cotinine assay.
The toxicology screening panel can detect amphetamines (amphetamine, 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxy-N-ethylamphetamine (MDEA), N,N-Dimethyldopamine (DMDA), and methamphetamine), cannabinoids (carboxy-THC), cocaine (benzoylecgonine), opiates (codeine, hydrocodone, hydromorphine, morphine, 6-Monoacetylmorphine (6MAM), and meconin), phencyclidine (phencyclidine), 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), methadone, and barbiturates (amobarbital, butalbital, pentobarbital, Phenobarbital, and secobarbital).