The European Commission put together a document in 2014 that you might find interesting which collates a lot of the academic research
www.europarl.europa.eu/RegData/etudes/etudes/join/2014/493040/IPOL-FEMM_ET(2014)493040_EN.pdf
Some select statistics:
"M. Farley’s study carried out across nine countries in 2003 showed that a majority of prostitutes had experienced severe forms of violence, including sexual assault and rape. In most of the cases, they experienced various types of repeated violence. A large proportion (68%) had suffered from Post-traumatic Stress Disorder (PTSD), with a level of severity comparable to that experienced by Vietnam War veterans, as well as psychological dissociation."
"In addition to the violence experienced in the context of prostitution, 43% to 69% of women selling sex have suffered sexual abuse in childhood"
"More than a fifth of them reported enjoying the feeling of power over the prostitute and believed that once the customer had paid, he could do whatever he wanted with the women he bought (22%)"
"M. Farley’s interviews with 785 people in prostitution in nine countries showed that 89% of them wanted to escape prostitution but had no other options for survival"
"According to M. Farley and Di Nicola, the knowledge that the women had been exploited, coerced, or trafficked failed to deter sex buyers from buying sex .In this respect, it has to be noted that most clients are unable to identify indications of forced prostitution"
"Furthermore, it has been observed that men (around 40%) justify or tolerate prostitution because they think that buying sex reduces the likelihood of rape and, if prostitution would not exist, then the number of rapes would increase . In fact, studies from the US seem to prove the contrary (please see above, sub-chapter 1.2.5.)."
"On average 70% of the prostitutes in the EU are migrant women."