Skip to main content
. Author manuscript; available in PMC: 2015 Jan 1.
Published in final edited form as: Obstet Gynecol. 2014 Jan;123(1):113–125. doi: 10.1097/AOG.0000000000000052

Table 3.

Maternal Report and Testing Results for Smoking and Drug Use by Stillbirth Collaborative Research Network Case Status for Nonanomalous, Singleton Pregnancies Excluding Intrapartum Stillbirths

Characteristic - Weighted %* Stillbirth Live Birth Odds Ratio (95% CI) P

Maternal report of smoking

Unweighted sample size – n 412 1,723

Weighted sample size – nw 405 1,304

Smoked trimester the baby was born
  No, never smoked 80.4 86.9 Reference 0.001
  No, smoked previously 9.5 7.4 1.40 (0.94, 2.07)
  Yes, 1–9 cigarettes/day on average 6.0 3.7 1.78 (1.07, 2.97)
  Yes, 10+ cigarettes/day on average 4.1 2.1 2.09 (1.10, 3.94)

  Test: linear trend 0.017

Cotinine Testing

Unweighted sample size – n 396 1,455

Weighted sample size – nw 387 1,131

Positive for cotinine 18.9 9.2 2.29 (1.66, 3.16) <.001

Cotinine concentration (ng/ml)
  Negative (<0.25) 81.1 90.8 Reference <.001
  Positive, <3 6.0 3.2 2.12 (1.27, 3.53)
  Positive, 3+ 12.9 6.0 2.39 (1.62, 3.52)
  Test: linear trend <.001

Cotinine concentration (ng/ml), by quartile for positives
  Negative (<0.25) 81.1 90.8 Reference <.001
  Positive, ≤1.49 4.0 2.1 2.12 (1.14, 3.94)
  Positive, 1.49 – 9.68 3.4 2.3 1.66 (0.87, 3.17)
  Positive, 9.68 – 23.62 4.8 2.5 2.18 (1.18, 4.04)
   Positive, >23.62 6.7 2.4 3.18 (1.83, 5.53)
Test: linear trend 0.001

Cotinine concentration (ng/ml), by median for positives
  Negative (<0.25) 81.1 90.8 Reference <.001
  Positive, ≤ 50th percentile (≤9.68) 7.4 4.4 1.88 (1.19, 2.97)
  Positive, > 50th percentile (>9.68) 11.5 4.8 2.67 (1.75, 4.07)

  Test: linear trend <.001

Maternal report of smoking and cotinine testing

Unweighted sample size – n 371 1,404

Weighted sample size – nw 363 1,095

Cotinine and smoking during the trimester the baby was born
<.001
  Negative cotinine (<0.25) & never smoked 75.0 84.6 Reference
  Negative cotinine (<0.25) & smoked previously 6.0 5.6 1.20 (0.72, 1.98)
  Negative cotinine (<0.25) & smoked 0.5 0.8 0.71 (0.15, 3.29)
  Positive cotinine, <3 ng/ml, & did not smoke 4.8 2.6 2.10 (1.18, 3.73)
  Positive cotinine, 3+ ng/ml, & did not smoke 4.1 1.5 3.03 (1.52, 6.06)
  Positive cotinine, any concentration, & smoked 9.6 4.8 2.24 (1.42, 3.52)

Cotinine and smoking during the trimester the baby was born
  Negative cotinine (<0.25) & never smoked 75.0 84.6 Reference <.001
  Negative cotinine (<0.25) & smoked previously 6.0 5.6 1.20 (0.72, 1.98)
  Negative cotinine (<0.25) & smoked 0.5 0.8 0.71 (0.15, 3.29)
  Positive cotinine, ≤ 50th %tile (≤9.68 ng/ml), & did not smoke 5.6 3.3 1.88 (1.11, 3.19)
  Positive cotinine, > 50th %tile (>9.68 ng/ml), & did not smoke 3.3 0.8 4.95 (2.10, 11.65)

Maternal report of lifetime drug use

Unweighted sample size – n 410 1,714

Weighted sample size – nw 402 1,288

Lifetime drug use
  Reported never used drugs 66.6 69.7 Reference 0.017
  Reported drug use
    Without addiction 28.5 28.1 1.06 (0.82, 1.37)
    With addiction 4.9 2.2 2.33 (1.31, 4.17)

Toxicology screening§

Unweighted sample size – n 297 993

Weighted sample size – nw 284 842

Positive for any drug 8.2 3.8 2.23 (1.29, 3.88) 0.004

Positive for specific drugs
  Morphine 1.5 0.4 4.19 (0.93, 18.98) 0.063
  Hydromorphone 0.0 0.0
  Codeine 0.4 0.2 1.81 (0.16, 20.31) 0.629
  Hydrocodone 0.3 0.0 95.29 (5.93, 1531.34) 0.001
  Pethidine / Meperidine 0.0 1.0
  THCA (tetrahydrocannabinolic acid) 4.9 1.8 2.83 (1.34, 5.99) 0.007
  Cocaine (Benzoylecgonine) 1.3 0.6 2.19 (0.57, 8.48) 0.256
  Amphetamine or Methamphetamine 0.7 0.1 7.61 (0.67, 85.98) 0.101

None, single or multiple drugs detected
  Negative for all drugs 91.8 96.2 Reference 0.015
  Positive for 1 drug 7.3 3.6 2.14 (1.20, 3.79)
  Positive for 2 drugs 0.8 0.2 3.71 (0.54, 25.42)

Maternal report of lifetime drug use and toxicology screening

Unweighted sample size – n 270 928

Weighted sample size – nw 259 784

Umbilical cord toxicology and lifetime drug use
  Negative for all drugs & reported never used drugs 61.4 68.7 Reference 0.008
  Negative for all drugs & reported drug use 30.6 27.7 1.24 (0.90, 1.70)
  Positive for any drug & reported never used drugs 2.7 2.0 1.56 (0.62, 3.87)
  Positive for any drug & reported drug use 5.3 1.6 3.79 (1.69, 8.53)

Cotinine testing and toxicology screening

Unweighted sample size – n 274 845

Weighted sample size – nw 262 715

Cotinine and drug use
  Negative cotinine (<0.25) & negative for all drugs 78.1 88.8 Reference <0.001
  Positive cotinine & negative for all drugs 13.5 7.6 2.02 (1.29, 3.16)
  Negative cotinine (<0.25) & positive for any drug 4.1 2.4 1.94 (0.88, 4.26)
  Positive cotinine & positive for any drug 4.3 1.1 4.35 (1.74, 10.84)
*

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).