Table 1. The background and cotinine levels in the study group.

	Non-smokers (n = 11)	Active-smokers (n = 8)	p value
Age (years)	37 (23–41)	32 (26–34)	0.199 a
Body weight (kg)	50 (48–58)	52 (45.5–54.5)	0.901 a
BMI	20.3 (20.0–22.2)	19.8 (19.2–20.4)	0.216 a
Self-reported smoker (n)	0 (0%)	5 (62.5%)	0.005 b
Serum cotinine (ng/mL)	0.3 (0.2–0.4)	130.8 (36.9–145.8)	<0.001 a
Crown-rump length	14 (11–17)	15 (10–16)	0.772 a

There were no significant differences in the maternal age, BMI, or crown-rump length between the non-smokers and the active smokers. The data are presented as the median and quartiles.

^a p values obtained using the Wilcoxon-Mann-Whitney method.

^b p values obtained using Fisher’s exact test.