About a third of all women in the world have been physically or sexually assaulted, according to a new study by the World Health Organization.

The report titled "Global and regional estimates of violence against women: Prevalence and health effects of intimate partner violence and non-partner sexual violence", shows the prevalence of violence against women, either by partners or others. About 30 percent of all women in the world are assaulted by their intimate partners.

"These findings send a powerful message that violence against women is a global health problem of epidemic proportions. We also see that the world's health systems can and must do more for women who experience violence," said Dr Margaret Chan, Director-General, WHO, according to a press release.

About 38 percent of the total murdered women were killed by their partners. Many suffered serious injuries and depression. The study also found that abused women are likely to have high prevalence of sexually-transmitted diseases and low birth-weight babies.

A related study conducted by World Health Organization had found that women abused by their partners are "twice as likely as non-abused women to have poor health and physical and mental problems, even if the violence occurred years before."

The report found that violence by intimate partners against women was particularly high in areas like Africa, Eastern Mediterranean and Southeast Asia.

"This new data shows that violence against women is extremely common. We urgently need to invest in prevention to address the underlying causes of this global women's health problem." said Professor Charlotte Watts, from the London School of Hygiene & Tropical Medicine.

Sadly, these high numbers might just be the tip of an iceberg as most women don't report violence due to social stigma, said WHO. Other problems like absence of such surveys in several countries and poor data collection methods also posed to be major challenge for gathering data on violence against women.

The report was released by the WHO along with the London School of Hygiene & Tropical Medicine and the South African Medical Research Council. The study and info-graphics can be found here.