A new rule raising the minimum age of marriage and civil partnerships from 16 to 18 in England and Wales has come into place.
Those aged 16 or 17 could previously get married with parental consent.
BBC News also reported that the new law also applies to cultural or religious marriages that are not registered with the local council.
Conservative MP Pauline Latham, who introduced the bill to Parliament, said it would "transform the life chances of many girls".
Children would not face penalties under the new rule, but adults who facilitate the marriage could face up to seven years in jail and a fine.
This would include adults who took children abroad to carry out the marriage.
The bill went through Parliament with little opposition and will receive Royal Assent later in the week, binding it into law.
The new law will not affect the validity of any marriages or civil partnerships that happened before the legislation comes into force.
It does not apply to Northern Ireland and Scotland, where the minimum age will stay at 16.
In Northern Ireland you still need parental consent to marry at 16, but in Scotland, you don't.
Complications in the new rule
BBC News reported that Mihai Calin Bica, of the Roma Support Group, said the bill was "a good initiative to protect our youth", but the group expressed concern "about how it will be applied in practice".
It noted that in Roma communities the word "married" was often used to explain boyfriend-girlfriend relationships their children have.
They warned this could create complications when enforcing the law and urged the government to run an educational campaign aimed at raising awareness of the new rules.
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