New figures released by counter-terrorism police show 56 British girls and women are thought to have fled from the UK for to Syria in 2015.
That is an increase of 13 on the 43 who reportedly travelled to the war-torn country in the previous 12 months.
The figures come as police released a video featuring three female Syrian refugees talking about the realities of life in their home country.
[caption id="" align="alignnone" width="589"] Zakaa, one of the Syrian women in the video[/caption]
The short film warns about the dangers of going to Syria to join Islamic State (IS) militants.
Helen Ball, the senior national coordinator for counter-terrorism, says people are often attracted by IS propaganda which paints an idyllic picture of life in the caliphate.
We are deeply concerned about the numbers of girls, young women and also families who are taking the decision to go to Syria," she said.
"(They are) unaware of the dangers they face when they arrive and the fact that they are unlikely to ever be able to return home to their devastated wider families."
Ms Ball added: "The personal accounts of the women in this film highlight the harsh reality of life for women and children living in a war torn country.
"I hope they will go some way to helping young women and mothers stop and think about the huge mistake they would be making if they travel."
The three women have also written open letters on the Prevent Tragedies website, which is part of the campaign to tackle radicalisation.
One of the mothers, Zakaa, says her husband was killed by a sniper.
"Please tell your daughter my story so that she can understand that Syria is a dangerous place to live and no place to bring up children," she wrote.
"Ask your daughter to think about what she has here in the UK - a country where she has safety and freedom of choice compared to Syria where, under ISIS control, she would have neither?
"ISIS is far from the views of Islam. They do not follow Islam and they are not Muslims .ISIS is more feared by Syrians than the Assad regime itself."
Recent high-profile profile cases have included school friends Shamima Begum and Amira Abase, both 15, and Kadiza Sultana, 16, all from Bethnal Green, east London.
They left for Syria in February and are now reported to be married to IS fighters.
Assistant Chief Constable Angela Williams said: "It is important for everyone do everything they can to help stop people from travelling to Syria and other conflict zones.
"Children have been taken to dangerous places and are at great risk; vulnerable people have been brainwashed into travelling.
"My message to mothers across the region is to please come forward if you have any concerns about your loved ones who may be considering travel to Syria."