The Harmful Connections report said more than one in 10 women reported being beaten while carrying a child.
The study — which focused on Fiji, Kiribati, Samoa, Solomon Islands, Tonga and Vanuatu — also found children who experienced violence at home were more likely to be perpetrators or victims of family violence when they reached adulthood.
UNICEF Pacific's chief of child protection, Amanda Bissex, said the study showed evidence of what has been understood anecdotally for some time.
“I think in some ways the intergenerational nature of violence is intuitive: we as children mimic the behaviour of the adults," she told Radio Australia's Pacific Beat program.
“So the child that grows up in a household where violence is a normal way of dealing with stress and conflict, and will grow up to mimic that behaviour as they get older.”
Some 23 per cent of women surveyed in Kiribati reported being beaten while pregnant. In Fiji the number was 15 per cent, and 11 per cent in Solomon Islands.
“You would think that during a time of pregnancy, there would be some protection of women from violence, but what we find is that's not the case,” Bissex said.
“And some of the forms of violence against women during pregnancy is very severe such as being kicked or punched in the abdomen.”
“I think its a reflection too of the widespread acceptance of violence ... against women and children."
In Kiribati, women who experienced intimate partner violence were two and a half times more likely to have a partner who was beaten as a child, and in Fiji, three times more likely.
“Many times we hear that people who grow up with violence when they're adults, particularly in the Pacific, will say 'I was hit as a child and it didn't have any impact on me, I'm okay,” Bissex said.
“But what this report tells us is the wide range of impacts that if you grow up in a violent household as a child, you're more likely to become either a perpetrator or a victim of violence.
“Violence against children, in some cases, even begins in the womb.”
Ella Kauhue from the Solomon Islands National Council of Women said she was not surprised by the data.
“Women experiencing aggressive violence, or whether it is in broad daylight on the street, it's something that happens all the time ... across the country and especially here in the capital,” she said.
She said violence against women and children would not stop overnight, but the first step was in the home.