Watch: National MP opens up about tragic death of her two-year-old son, in maiden speech to Parliament

National MP Denise Lee has given a heartfelt maiden speech to Parliament where she talked about the death of her two-year-old son being a driving force behind her political career.

The MP for Maungakiekie began her speech with a Maori welcome before later talking about the unexpected loss of her two-year-old son Riley.

"One night I awoke as a young parent and decided to check on my two year old son Riley only to discover he had died in his sleep.

"What ensued was a series of random interactions with a cold-hearted function-driven system.

"The failure of police inquest officers, pathologists and coroners to sensitively inform and communicate their process to two shell-shocked parents still mystifies me today," Ms Lee said.

The ordeal played a large role in the National MPs decision to change what she saw as a broken system.

"This indignance formed a seed that merged into a big part of the driving force that sees me standing here today.

"Politics really did become personal for me then. A flick of the pen, wording of an amendment, an exchange in the debating chamber - parliament’s processes affect everyday lives," she said.

Ms Lee also said she believes the system has since improved for the better with the 2006 Coroners Act better protecting grieving families.