To date, research on the sexual and reproductive health of female sex workers (FSWs) has primarily focused on vulnerability to sexually transmitted infections (STIs), particularly HIV infection [1]. However, FSWs also may be at high risk of pregnancy, as most are of reproductive age and many experience frequent vaginal intercourse without adequate access to contraceptives [2, 3]. However, the broader reproductive health and pregnancy patterns of FSWs, particularly those who use drugs, have been largely neglected in research and public health interventions globally. Understanding the availability and use of contraceptives as well as pregnancy patterns among FSWs who use drugs is essential to develop more comprehensive, women-centred reproductive health services that promote positive maternal and child health and reduce adverse outcomes such as maternal mortality, unsafe abortions, the vertical transmission of HIV/AIDS, and poor birth outcomes for children of FSWs.

Access to reproductive health services, including contraceptives, prenatal care and mothering services [4], are a basic human right [5, 6], and are particularly important for marginalized, drug-using women who may experience higher rates of maternal morbidity, mortality and negative obstetric, fetal and child outcomes as a result of drug use during pregnancy [7–10]. While research about access to reproductive health services among drug-using FSWs is scarce, a number of studies report that substance-using mothers experience limited or no access to prenatal care because of the stigma attached to maternal substance use during pregnancy [11–13]. Current child-centred policies in Canada have also been found to pose significant barriers to accessing appropriate reproductive health and treatment programs among women who use substances during pregnancy; many women avoid these services for fear of losing custody of their children [14]. The lack of recognition of the reproductive health needs and rights of women who use drugs limits their access to appropriate and non-judgmental reproductive health care services [15, 16]. In addition to barriers posed by their drug use, FSWs' involvement in sex work may further limit their access to reproductive health services. Police surveillance and crackdowns have been found to displace street-based FSWs to peripheral areas, away from health care services [17, 18]. Elsewhere, a lack of targeted services, expensive travel costs, health care service hours and sex work stigma have been identified as barriers to health and social services among FSWs [19], and could potentially restrict access to reproductive health services and impact levels of pregnancy and contraceptive usage among women in our sample.

Most previous studies on reproductive health practices and outcomes of FSWs have been among FSWs living in developing countries. Our literature search yielded no studies that explicitly focused on the reproductive health needs of street-based FSWs who use drugs in industrialized countries. Thus, we undertook a study of street-based FSWs living in Vancouver, Canada, to: (1) describe levels of contraceptive usage, prior pregnancy and pregnancy outcomes (including abortion, adoption, child apprehensions, miscarriage, child custody arrangements); (2) examine the correlates of having a high number of prior pregnancies (defined as having greater than the mean number of pregnancies (5+)).

Data were obtained from a community-based prospective cohort of the BC Centre for Excellence in HIV/AIDS, in partnership with a local sex work agency, Women's Information Safe Haven (WISH) Drop-in Centre Society. The study approach has been described in detail previously [20]. Briefly, between 2006 and 2008, 252 street-based female sex workers were recruited using targeted outreach at solicitation spaces, based on mapping and time-location sampling. While this was not a random sample, time-location sampling has been increasingly used as a method for recruiting hard-to-reach populations at times and spaces where they congregate. The study's eligibility criteria included: self- identifying as a woman (including transgender), aged 14 years or older, actively engaged in street-level sex work and having used illicit drugs within the past month (excluding marijuana). Participants who consented and were enrolled in the study completed a baseline and 6-monthly follow-up interview-administered questionnaires by trained peer researchers (current or former street-based sex workers). Additionally, nurse-administered pre-test counseling and HIV screening using Biolytical Laboratories INSTI™ Rapid HIV Antibody Test (specificity 99.3%, sensitivity 99.6%) were conducted. At baseline, a detailed semi-structured questionnaire covering demographics, health service use, working conditions, violence, sexual and drug risk practices was administered. Participants received $25 remuneration for their time and expertise. Ethical approval for this research was received from the UBC/Providence Health Ethics Review Board.

Of the 211 women eligible for this study, 176 (84%) women reported ever being pregnant. The median age of women reporting 5+ pregnancies was 38 years old [interquartile range (IQR): 25.0-39.0] compared to 34 years [IQR: 25.0-39.0] among women reporting 4 or fewer prior pregnancies. The median age of first sex work was 17 years of age [IQR:15-25]. Forty-five percent were Caucasian and 47% were of Aboriginal ancestry. Forty-seven (22%) reported being HIV positive, and 33(16%) were HIV positive, and taking Highly Active Antiretroviral Therapy (HAART). Approximately half (49%) of the women in our sample had non-commercial, intimate partners within the last 6 months of the interview.

Drug use was prevalent among our sample, with 103 (48.8%) having reported using heroin, 71 (33.7%) who used cocaine and 53 (25.1%) having reported intensive crack use (> 10 rocks per day) 6 months prior to the interview. The median age for initiation of injection drug use was 17.5 years [IQR = 15-23], and the median age of crack cocaine use was 20 years [IQR = 16-29.8].

Among this cohort of FSWs, we found a high prevalence of lifetime pregnancy, abortion and child apprehension, and low utilization of hormonal and insertive barrier contraceptives. On average, the women in this study reported four pregnancies during their lifetime, which is nearly three times the fertility rate of the general Canadian population [22].

Among our entire sample of 211 FSWs, 76 (36%) abortions were reported (median of 1, [IQR:1-3]). The self-reported prevalence of abortions among our cohort suggests a much higher level of unintended/unwanted pregnancy compared to the general Canadian population; the Canadian induced abortion rate is 14.1 per 1,000 women aged 15-44 [23]. Despite the lack of data on abortions among drug-using FSWs in resource rich countries, a few studies in low and middle-income countries have also reported high rates of abortion among FSWs [2, 24]. For example, a study in Colombia found that 53% of FSWs interviewed reported having ever had an abortion [24]. Results from a Kenyan survey revealed an 86% prevalence of lifetime abortion among FSWs, with 50% of respondents reported having more than one [25]. Abortion data amongst the women enrolled our study are comparable to those in low-resource settings and suggest that despite legalized abortion and universal health care access in Canada, many women, particularly marginalized women, could benefit greatly from improved uptake of effective contraception and improved access to reproductive and sexual health care, including abortion services. Since our study does not capture abortions post-interview, our findings likely underestimate the true rate of lifetime abortions among FSWs. Additionally, though abortion rates can be used as a proxy for unwanted pregnancy, our findings likely underestimate the true rate, since access to abortion services may be limited among this population.

While evidence of female-controlled contraception among FSWs in our setting is scant, the limited use of contraceptives in our study is comparable to findings in resource-poor settings [1, 2, 26], and may suggest low access to female-controlled contraceptives and reproductive health services in this setting [27]. Other studies in our setting have found low utilization of health care services in general, due to the marginalization of FSWs and drug users, and their reluctance to use health and social services [27, 28]. Avoidance of police and individual zoning restrictions (resulting from previous drug or solicitation charges) restrict FSWs' access to health services [29]. The high rate of child apprehension observed in our sample may further act as a barrier to seeking health care and social services [14]. Such policies that restrict access to health and social services can deny FSWs of enabling environments necessary to exercise their reproductive rights. Low access to reproductive health and mothering services (including antenatal care) may be of concern, considering the high rates of pregnancy among FSWs in our study. Contextual factors, such as poverty and homelessness, may reduce FSWs' ability to travel to clinics [19], or purchase hormonal contraceptives. Moreover, the instability arising from homelessness and illicit drug use may not be conducive to hormonal contraceptives such as the birth-control pill, which require routine and strict adherence, and annual or semi-annual prescription renewals. Homelessness has been associated with decreased access to health care services [30], and may also limit access to contraceptives. Illicit drug use may further exacerbate barriers to accessing contraceptives [24], although we found that illicit drug use and economic dependence on one's partner were not significantly associated with higher number of pregnancies. Additionally, perceptions of negative side effects (e.g., physical and emotional side effects; long-term health effects) of hormonal contraceptives may also contribute to their low uptake [31]. Additional studies are needed to elucidate the reasons for low use of hormonal and insertive contraceptives among FSWs.

The higher rate of condom use compared to hormonal contraceptives, particularly among younger FSWs, may reflect their knowledge of condoms' dual role in pregnancy and STI/HIV prevention. Low or no-cost condoms and their widespread availability also may contribute to the relatively higher use of condoms compared to other forms of contraceptives. Additionally, we found the rate of condom use (primarily by intimate/regular partners) to be much lower than the reported rate of consistent condom use by FSWs' clients from a previous study in our setting (72%) [21]. The low rates of condom use by intimate partners point to the need for dual protection from STIs/HIV and unwanted pregnancies. Long-lasting, female-controlled contraception methods, such as injectable hormones, may be effective in reducing unintended pregnancy. Permanent contraceptives usage was high among our sample, particularly tubal ligation and hysterectomy. The hysterectomy rate among our sample is exceptionally high when compared to the Canadian rate of 338 per 100,000 population [32]. The factors contributing to this prevalence in our study are unclear and warrant further attention.

This study has a number of limitations. The findings from this study may not be generalizable to FSWs working in other venues, such as bars, massage parlours and/or escort agencies. Given the sensitive nature of the topic, and our reliance on self-report data, the responses obtained in this study may be subject to social desirability bias. However, previous studies suggest that sex workers and drug users provide truthful accounts of their sex and drug use activities when questioned in a non-threatening environment [33]. Additionally, our study may underestimate the true rate of lifetime pregnancy and abortion among FSWs, as pregnancies post-interview are not captured. In the absence of data about pregnancy intention/desires, we used abortion rates as a proxy for unwanted pregnancy, which may limit our estimation of the true rate of unwanted pregnancy. However, induced abortion has been used as a proxy for unwanted pregnancy in other studies [34]. Finally, our small sample size (particularly our sample restricted to FSWs who had ever been pregnant) may have limited our statistical power to detect associations with high pregnancy levels.

The high levels of unwanted pregnancy and underutilization of effective contraception suggests that FSWs who use drugs may not have access to knowledge or resources, such as contraceptives or reproductive health services, that allow them to have full control over their reproductive health. It is imperative to develop targeted services for FSWs that extend beyond HIV/STI prevention and comprehensively address reproductive health needs. The core principles of women-centred care, which emphasize women's autonomy, empowerment, safety, diversity and complexity as well the importance of social context in shaping reproductive health [35], need to be considered in order to better attend to the specific reproductive health needs of FSWs. Efforts to improve access and utilization of reproductive health services amongst this population also need to address other barriers, including the fear of child apprehension when help-seeking, particularly during pre- and post-natal periods. Comprehensive outreach services that include family planning and reproductive health services may hold promise for better serving this population [21, 36].