A CANADIAN woman pregnant with her third child says she was served a chemical cleaning agent at a McDonald’s restaurant instead of the latte she ordered.

Sarah Douglas was taking her son to a baseball tournament on Sunday morning in Alberta when they stopped at a McDonald’s drive-thru for the coffee.

When she took a sip she knew something was wrong and pulled over to spit it out.

“I had no idea what I was drinking,” she reportedly said. “I just knew it wasn’t coffee and tasted like chemical.”

Ms Douglas returned to the restaurant with the coffee to complain, she was shocked to see the coffee machine was still connected to a bottle of cleaning chemicals.

A spokeswoman for McDonald’s issued an apology on behalf of Dan Brown, the restaurant franchisee.

“Since learning about the complaint, our team has been in very close contact with the guest and apologised to her,” the statement read.

“The health inspector also visited my restaurant and is not investigating further.

“What happened is that the machine was being cleaned — as it is every morning. Unfortunately, the milk supply line was connected to the cleaning solution while this guest’s drink was made.”

Ms Douglas contacted poison control and met with her doctor as a precaution.