Table 1.
Population characteristics of mothers and infants with completed doppler ultrasound.
| Nonsmokers (n=33) | Placebo-treated smokers (n=26) | Vitamin C-treated smokers (n=29) | p-value vitamin C vs. placebo | |
|---|---|---|---|---|
| Maternal characteristics at randomization | ||||
| Age at enrollment, median (IQR), years | 32 (29–33) | 24 (22.25–32) | 28 (21–32) | 0.953 |
| Race, n white (%) | 30 (90.9) | 21 (80.8) | 27 (93.1) | 0.308 |
| Gravida, median (IQR) | 2 (1–3) | 2.5 (1–4.8) | 3 (1–3) | 0.753 |
| Body mass index at enrollment, mean (SE) kg/m2 | 27.83 (1.01) | 30.78 (1.37) | 26.71 (0.79) | 0.020 |
| History of asthma, n (%) | 5 (15.2) | 5 (19.2) | 10 (34.5) | 0.335 |
| Private health insurance, n (%) | 31 (93.9) | 5 (19.2) | 4 (13.8) | 0.471 |
| Gestational age at randomization, median (IQR), weeks | NA | 17.75 (14.8–19.53) | 17.9 (14.7–19.4) | 0.627 |
| Maternal cigarettes/day during pregnancy, median (IQR) | NA | 8 (4.25–10) | 8 (5–10) | 0.898 |
| Urine cotinine at randomization, median (IQR), ng/mL | Not detectable | 5197 (1885–8302) | 5418 (1872–7278) | 0.959 |
| Plasma ascorbic acid at randomization, mean (SE), µmol/L | Not measured | 41.9 (3.1) | 46.2 (3.3) | 0.416 |
| Plasma ascorbic acid at mid-gestation mean (SE), µmol/L | Not measured | 32.2 (2.8) | 57.9 (4.3) | <0.001 |
| Plasma ascorbic acid at late-gestation mean (SE), µmol/L | Not measured | 33.47 (3.1) | 45.7 (3.9) | 0.016 |
| Patient characteristics at Doppler ultrasound | ||||
| Time from last cigarette, median (IQR), h | NA | 1.3 (0.58–1.41) | 1.11 (0.53–1.46) | 0.454 |
| Gestational age at ultrasound, median (IQR), weeks | 35 (33.4–36.2) | 32.8 (32.3–34.3) | 34.2 (32.3–35.2) | 0.423 |
| Birth characteristics of infants | ||||
| Birth weight, mean (SE), g | 3571.8 (76.3) | 3175.9 (97.1) | 3142.4 (105.2) | 0.958 |
| Placental weight, mean (SE), g | Not measured | 584.45 (142.75) | 612.19 (119.88) | 0.551 |
| Gestational age at birth, median (IQR), weeks | 39.6 (39.1-40.0) | 39.1 (38.3-39.6) | 38.6 (37.3-39.6) | 0.140 |
| Female, n (%) | 19 (57.6) | 12 (46.2) | 11 (37.9) | 0.731 |
| Preterm, <37 weeks gestation, n (%) | 0 (0) | 0 (0) | 5 (17.23) | 0.080 |
Significant values are in bold.
Normally distributed variables are expressed as mean and standard error and compared for group differences using an unadjusted F-test. Non-normally distributed variables are expressed as median and interquartile range (25th–75th percentile) and the Wilcoxon rank sum test was used to compare groups. Chi-square test was used to compare categorical variables.