Teen sentenced over robbery of pregnant woman

A teenager could be free in just three months after being sentenced over a violent, broad-daylight robbery on a pregnant Perth mother.

Shocking footage released by WA Police shows the 15-year-old girl pulling the woman to the ground by her hair, as she walked her babies in a pram in September.

The girl is seen yanking the 19-weeks-pregnant mother by the hair and pulling her to the ground in Perth's north-eastern suburbs.

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The pram carrying her two-year-old twin girls is upended, sending the babies upside down and their little legs dangling.

The mother is then dragged at least 10 metres and hit in the head, all the while defending her handbag.

The 15-year-old girl had only been released on bail two days before the robbery, for another violent crime.

The teen was brought to tears today, unleashing an angry tirade as she blamed her cousin for telling her to carry out the attack.

She told a judge she hadn't been thinking straight, admitting to cannabis use in recent months.

Had she known the woman was pregnant she wouldn't have listened to her cousin, the court heard.

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The judge slammed the teen's actions as sickening but a psychological report revealed her dysfunctional upbringing normalised violence.

The girl was handed a 12-month backdated detention sentence.

But she could be free on supervised release in just three months.