Table 3.

Seasonal variation in confounding factors

Factor	Winter	Spring	Summer	Fall	P-value
Sexual Factors
Mean vaginal sex frequency*	2.2/week	2.2/week	2.4/week	2.4/week	0.004
Mean oral sex frequency*	0.6/week	0.6/week	0.6/week	0.6/week	0.79
Mean number recent sex partners*	0.90	0.90	0.97	0.95	<0.001
New sex partner*	8%	8%	8%	8%	0.78
Hormonal contraception	47%	47%	49%	49%	0.79
Health-related Factors
Weight (kg)	81.8	80.6	80.2	81.2	<0.001
Smoking	28%	29%	28%	30%	0.18
Alcohol drinking	54%	53%	51%	51%	0.009
Metronidazole since last visit**	15%	15%	13%	15%	0.04
Hygiene-related Factors
Douching*	43%	43%	44%	45%	0.14
Powder on genitals*	23%	23%	21%	25%	0.03
Towelette use*	9%	8%	7%	7%	0.03
Feminine deodorant spray*	13%	12%	10%	12%	0.07
Showers only*	9%	9%	11%	9%	†
Baths only*	15%	16%	15%	15%	†
Baths and showers*	76%	75%	74%	77%	†

^*In past 6 months at initial study visit, in the past 3 months for follow-up visits

^**In past 2 weeks for first study visits, since previous visit for follow-up visits

^†shower vs bath and shower, p=0.01; bath only vs. bath and shower, p=0.13; bath only versus shower only, p=0.07.