Exploring Genitoanal Injury and HIV Risk Among Women: Menstrual Phase, Hormonal Birth Control, and Injury Frequency and Prevalence

BACKGROUND: Genital, anal and oral injuries sustained from sexual intercourse may explain HIV transmission among women. We determined the variability in genitoanal injury frequency and prevalence in women following consensual sexual intercourse, exploring the role of menstrual phase and hormonal birth control. METHODS: We used a longitudinal, observational design with a convenience sample of 393 women aged 21 and older. Participants had a baseline interview with gynecologic examination, followed by consensual sexual intercourse with a male partner and a second gynecologic examination. We analyzed injury prevalence with logistic regression and injury frequency with negative binomial regression among women who were: a) menstrual, not using hormonal birth control, b) menstrual, using hormonal birth control, or c) menopausal. We also compared injury among menstrual women in the follicular, ovulatory and luteal phases. FINDINGS: Women using hormonal birth control had 38% more external genitalia injuries (adjusted rate ratio [ARR] = 1.38, p = 0.030) and more than twice the anal injuries (ARR = 2.67, p = 0.005) as the non-hormonal birth control menstruating group. Menopausal women had more than three times the anal injuries (ARR = 3.36, p = 0.020) than those in the non-hormonal menstrual group. Among menstrual women, those in the follicular phase had a greater prevalence and frequency of external genitalia injuries than those in other phases. INTERPRETATION: Increased rates of post-coital genitoanal injuries are noted among women using hormonal birth control and/or in the follicular phase of menstruation. Biological factors that influence women's risk for HIV warrant further investigation. Language: en