POLICE claim a woman with a four-month-old child in the back has crashed in Mandogalup before returning an alleged blood alcohol reading close to three times the legal limit.
It is also alleged the car the pair were travelling in was unregistered.
Police were called to the scene of the single vehicle rollover on Kwinana Freeway southbound at the Rowley Road exit at 12.45am this morning.
There they found the 29-year-old woman and the baby unharmed. Both were taken to Fiona Stanley Hospital as a precaution.
The woman is expected to be charged by summons in relation to the drink driving and vehicle offences.