Two friends who went to see Bad Moms 2 were turned away – because the movie was R16 and they had their babies with them.
The babies were aged 5 weeks and 5 months.
National and Hutt South MP Chris Bishop reported his friend's experience on Facebook, under the heading, "thinking about possible law changes".
"Calling Mums and Dads - has anyone ever been denied entry to a restricted (e.g R16) movie with a small (under 12 months) child? A friend of mine the other day (and her friend) tried to take their 5 week and 5 month old babies with them to see "Bad Moms 2" (yeah, yeah...I know) and were told it was R16. No dice.
"Seems a bit silly to me... what do you reckon?"
Bad Moms 2 stars Mila Kunis and Kristen Bell, and has an R16 rating because the movie contains drug use, sexual references and offensive language.
According to promotional material, the movie follows three "under-appreciated and over-burdened moms as they rebel against the challenges and expectations of Christmas".
Bishop said if he did decide it was worth changing the law to exempt babies with their parents from film age restrictions, it could be progressed as part of a statutes amendment bill – an omnibus bill that makes a range of amendments to different legislation, in order to save Parliament's time.
His friend had tried to buy tickets to a mid-afternoon session, and was amused and frustrated when told they couldn't buy tickets because their babies were under age.
"My initial reaction was, that seems a bit stupid. There are R16 laws for a reason, but they are not there to protect a five week old kid."
Bishop said the reaction to his Facebook post had been polarising, with a lot of people saying babies shouldn't be taken to movie theatres at all.
Other people had told him they had been to "mums and bubs" sessions at cinemas, including to watch age-restricted movies.
"Clearly it is probably a law that is not always enforced, for the very reason it seems a bit harsh on mums and dads who want to take small kids in."