A pregnant woman has been flown to hospital to give birth after flood waters in North Richmond stopped paramedics from taking her by road.

The 37-year-old was being driven to hospital in an ambulance when flooding from the Nepean River stopped the vehicle from crossing.

A CareFlight chopper was called for help just before 4pm on Monday and landed about 20 minutes later along Beaumont Ave.

The woman was then placed in the care of the helicopter's specialist doctor and a NSW Ambulance critical care paramedic.

She was flown to Nepean Hospital in a stable condition.

Flood waters covered the Windsor bridge, built last year to be "flood proof", on Monday.

The bridge was closed on Sunday.

Floodwaters are expected to rise to crisis levels at Windsor, Pitt Town, North Richmond, Freemans Reach and Colo.

Penrith and other towns and suburbs along the Nepean were told to evacuate on Sunday as the state endured devastating floods after almost a week of heavy rainfall.

Originally published as Floods threaten pregnant woman in labour

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