This prospective study was ancillary to the large multicentre ECHO trial, a rigorous RCT that found no clear difference in HIV incidence among women randomised to DMPA-IM, the copper IUD and the LNG implant. Three hundred and ninety women in this ancillary study completed 27 or 28 days of their daily diaries and we used logistic regression to investigate behavioral risk factors for HIV acquisition using these data. The overall incidence of HIV in our cohort (8.4%) was higher than that of the main ECHO trial (5%), highlighting the enormous risk of HIV infection among contraceptive users in our South African setting.
As expected, oligo-amenorrhoea, a well-known side effect of progestin-only contraceptives, was much more common among DMPA-IM and LNG implant users than IUD users. As an apparent consequence of this outcome, intra-menstrual coitus was significantly more common among copper IUD users than users of the progestin-only methods. This was also a finding of the main ECHO trial, in which women were asked to recall at each follow-up visit whether they had had sexual intercourse during menses in the preceding three months.10 Among ECHO trial participants, the frequency of intra-menstrual coitus (reported as 7·2%, 9·1% and 7·1% for DMPA-IM, the copper IUD, and the LNG implant, respectively), was much lower than that reported in our study, in which almost half of the participants had at least one episode of intra-menstrual coitus during the 28 days of study. This difference is probably a result of the different methodology employed, as recall in our study was a daily reflection, as opposed to recall in the main ECHO trial, which involved reflection over the preceding 90 days. However, the relative effects found in the ECHO trial were in the same direction, and statistically significant for DMPA-IM vs the copper IUD (p < 0·0001), as our study.
In our study, DMPA-IM users had the highest rates of amenorrhoea, the shortest duration of menstruation, and the lowest frequency of intra-menstrual coitus, probably because most women in this group experienced no menstruation during the study period. Conversely, copper IUD users had the lowest rates of amenorrhoea, the longest duration of menstruation and the highest frequency of intra-menstrual coitus. DMPA-IM users also had the highest coital frequency, which could be due to less days of menstrual bleeding and, therefore, more days available for coitus outside of menses. Higher rates of dysmenorrhoea may also have contributed to the lower coital frequency seem amongst copper IUD users in our study.
The main ECHO trial found no difference in self-reported coital frequency between groups.10 However, as mentioned above, these findings were based on recall of sexual activity over the past 90 days, which is likely to be less accurate than daily recall of events from the preceding 24 hours.
DMPA-IM users in our study were less likely to use condoms than copper IUD and LNG implant users. This may be because condoms were more likely to be used when coitus occurred during menstruation. Copper IUD users had the highest rate of condom use with steady partners. Again, this may be because menstruating women were more likely to use condoms, and copper IUD users had more intra-menstrual coitus than the other groups.
Our findings on reported condom use differ from those of the main ECHO trial, however, which found higher condom usage amongst the DMPA-IM users.10 This difference may be due to behavioral differences between the study sites, but could also be a function of recall bias that might have occurred in the main ECHO trial in relation to this outcome.
Whilst no statistically significant associations with potential risk factors were found, the odds of HIV acquisition was increased with the occurrence of intra-menstrual coitus and reduced with longer duration of menstruation. Intra-menstrual coitus occurred in 49% of our study sample, indicating that this practice is common in our population. This is higher than found in another South African study that reported a lifetime incidence amongst 531 women of coitus during genital bleeding (80% of which was menstrual) of 26%.16 Women in this study who reported the latter were over four times more likely to have been diagnosed with a sexually transmitted infection (STI) including HIV.16 Similarly, a North American study reported an incidence of intra-menstrual coitus of around 26% among 1586 women, finding a “strong statistical association” of intra-menstrual coitus and self-reported STI history, and suggesting that this practice might emerge as a risk factor for heterosexual transmission of HIV.17 Another study of HIV risk factors among women in the Dominican Republic reported that engaging in intra-menstrual coitus was associated with a three-times increased risk (OR 3.2) of being HIV positive.18 In addition, other studies have linked sexual exposure during menstruation with an increased risk of gonococcal infection.20,21
Our finding of a tendency to a negative association between menstruation and HIV acquisition suggests that menstruation might be a protective factor for HIV acquisition, probably because women are less likely to engage in sexual intercourse during their menstrual periods and therefore have less sexual intercourse overall compared with women who do engage in intra-menstrual coitus. Women (and men) may intuitively feel more exposed to the risk of STI acquisition during menstruation and may prefer to avoid intra-menstrual coitus. In addition, decision-making about condom use during menses may be influenced by the desire to avert acquisition or transmission of STIs.22 Reduced coitus and increased condom use during menses could also be related to an aversion to blood contamination, or for cultural or religious taboos;23,24 avoidance of intra-menstrual coitus is common to the teachings of all major religions.25
The United Kingdom’s National Health Service advises using a condom for sex during menstruation to prevent HIV and other STIs.26 However, more needs to be done globally to convey the importance of dual protection, especially during menstruation, and particularly where HIV and other STI rates are extremely high, as in our setting.
This ancillary daily diary study has several strengths: it was conducted alongside a rigorous RCT in which participants had been randomly assigned to contraceptive methods, therefore selection bias is unlikely to be responsible for behavioral differences. There were similar numbers of participants in each intervention group with similar baseline characteristics to the study center cohort; therefore, bias due to selective participation is unlikely. In addition, recall bias was minimized through the use of a daily symptom and behavior diary.
However, it also has several limitations. We correlated HIV acquisition during the course of the ECHO trial with a daily diary commenced and completed during the second month after enrolment; a subsequent follow-up diary would have been preferable to confirm these findings. In addition, the lack of significance in the findings on intra-menstrual coitus may have been due to the small sample size.