Violence by an intimate partner is increasingly recognized as an important public and reproductive health issue. Intimate partner violence is highly prevalent, with population based surveys finding lifetime prevalence rates of physical and/or sexual partner violence between 15 and 71% [
1]. As recognition of the prevalence of intimate partner violence and its negative sexual and reproductive health outcomes has grown [
2,
3], it is important to understand more about its association with induced abortion and pregnancy loss in different settings.
Studies conducted in low-income countries that used population-based, representative survey data, namely Bangladesh [
4], India [
5], Cambodia, the Dominican Republic, and Haiti [
6] have found an association between physical and/or sexual intimate partner violence and induced abortion and pregnancy loss. The study conducted in Bangladesh, using the cross-sectional, nationally representative 2004 MEASURE Bangladesh Demographic Health Survey found that 76% of Bangladeshi women experienced violence from husbands and that those women who experienced violence from their husbands were more likely to report both unwanted pregnancy and a pregnancy loss in the form of miscarriage, induced abortion, or stillbirth [
4]. The study from India drew on population-based data from two rural communities in Uttar Pradesh and Tamil Nadu collected in 1993 to 1994 and found support for an association between pregnancy loss and intimate partner violence [
5]. In both of these studies the association even persisted after controlling for recognized explanatory factors such as education, poverty and parity. An analysis of the population based, representative Demographic and Health Survey data from Cambodia, the Dominican Republic and Haiti, conducted in 2000 and 2002 also showed an association between ever experiencing intimate partner violence and having had a pregnancy that ended in a non-live birth. Unfortunately this study did not differentiate between miscarriage, stillbirth and induced abortion [
6].
Most studies from high income countries also support this association [
7-
9], for example a population-based, study from New Zealand, which had a similar design to the WHO multi-country study on which this paper is based on found that women who had ever experienced intimate partner violence were 1.4 times more likely to report they had ever had a miscarriage compared with women who had never experienced violence, and were 2.5 times more likely to report they had ever had an abortion, even after controlling for potential confounders [
7]. Still, a prospective study among predominately low income, African-American pregnant women in the US did not find an association between intimate partner violence and pregnancy loss [
10]. Until now, only one study using population-based data using the Cameroon Demographic Health Survey has been conducted in Sub-Saharan Africa to investigate whether exposure to physical, sexual and/or emotional intimate partner violence is associated with induced abortion and pregnancy loss [
11]. This study found that women who were exposed to spousal violence were 50% more likely to experience at least one episode of pregnancy loss compared with women not exposed to abuse [
11].
We hypothesized four pathways on how intimate partner violence can lead to adverse reproductive health outcomes in general and pregnancy loss in particular. The first pathway is direct, assuming that pregnancy loss is caused by direct physical trauma [
12,
13]. The other pathways are based on indirect associations. The first indirect pathway suggests that intimate partner violence is associated with pregnancy loss due to the women's stress related physiological responses to intimate partner violence, which can lead to low weight gain during pregnancy, restricted intrauterine growth, hypertension and infections during pregnancy [
14,
15]. The second indirect pathways is based on the assumption that intimate partner violence negatively impacts women's prenatal risk and health seeking behaviour, which may include alcohol and substance abuse during pregnancy as well as lower rates of antenatal care seeking and not seek hospital based delivery [
2,
16]. The third indirect pathway, which is also a potential explanation for the association between induced abortion, is that intimate partner violence can increase women's inability to negotiate contraceptive methods with her partner, which may lead to unintended pregnancy and thereby higher rates of induced abortions [
16-
18]. Even if unintended pregnancies are not terminated, evidence has shown an association with poor pregnancy outcomes [
19]. Additional hypothesized pathways linking intimate partner violence and induced abortions are that abused women might be more likely to have had an induced abortion because their abusive partners forced them to have one or because the women feel unable to raise a child in an abusive relationship [
7,
20].
The WHO Multi-Country Study on Women's Health and Domestic Violence, on which this study is based found that the prevalence of physical and/or sexual intimate partner violence in Tanzania is high, with estimates of 41% in the Tanzanian capital Dar es Salaam and 56% in the rural region Mbeya [
1]. A representative household survey of women aged 20 to 44 in the urban district of Moshi, Tanzania, conducted in 2002 to 2003 found a prevalence of 26% for experiencing threats of physical abuse, being subjected to physical abuse and forced intercourse by a partner [
21]. In addition, rates of pregnancy loss and induced abortion are also expected to be above average in Tanzania, with the 2003 estimated global induced abortion rate being 29 per 1000 women aged 15 to 44, and the rate in Eastern Africa being 39 per 1000 women [
22,
23]. Given that induced abortions are illegal in Tanzania unless the woman's life is in danger, the majority of them are carried out under unsafe conditions and therefore carry a high risk of adverse maternal health outcomes [
24]. In an ethnographic study in rural Mwanza, which drew on participant observation, group discussions and individual interviews, women revealed a variety of potential unsafe, clandestine methods to achieve illegal abortions. These include ingestion of dangerously high doses of medication or products not intended for human consumption, trusting people without appropriate skills, training or resources to perform manual abortions. Apart from the serious health consequences, this study also revealed that having to ask for an abortion made women vulnerable to financial and sexual exploitation due to the social ostracism they had to fear [
24].
Due to the limited evidence on the association between intimate partner violence on induced abortion and pregnancy loss from population-based studies in sub-Saharan Africa, this study aims to investigate the relationship between intimate partner violence and induced abortion and pregnancy loss in the United Republic of Tanzania and to estimate its strengths relative to other explanatory factors, such as age, education, economic stress, marital status, extramarital affairs and number of children.