Officers from the Mablethorpe and Alford policing team were flagged down on the A158 just before midnight on Saturday night.
They tweeted: “Night turn officers flagged down to assist woman in labour at the side of busy main road. Wasn’t expected putting their boots on last night.”
Their action has been praised by Police and Crime Commissioner Marc Jones, who shared the tweet and said: “Think policing is all about crime? Think again! Our communities rely on professionalism & skill of officers & staff for many things #welldone”
A spokesman from Mablethorpe and Alford Police said the woman made ot safely to hospital before the baby arrived.