DNA methylation in placentas. a DNA methylation in female and male fetal placentas determined by the Elisa method using 5-mC-specific antibody (non-smoking female group N = 6, non-smoking male group N = 9, smoking female group N = 7, and smoking male group N = 5). Data represent the mean of two experiments. b Percentage of AluYb8 DNA methylation at five consecutive CpG sites (non-smoking group N = 19 and smoking group N = 13). c AluYb8 DNA methylation in males and females (non-smoking female group N = 7, non-smoking male group N = 12, smoking female group N = 8, and smoking male group N = 5). d Percentage of LINE-1 DNA methylation at three consecutive CpG sites (non-smoking group N = 22 and smoking group N = 17). e LINE-1 DNA methylation in males and females (non-smoking female group N = 9, non-smoking male group N = 13, smoking female group N = 9, and smoking male group N = 8). Percentages of methylation were calculated and displayed as described in the legend for Fig. 1. Unpaired t test was used to compare non-smoking and smoking exposed group, while two-way ANOVA was used to compare combined effects of smoke exposure and gender. *Indicates statistical significance, p