Michaela Martin's favourite washing powder is tropical lily and ylang ylang-scented Surf.

To eat, that is ...

Now the 23-year-old mum-to-be has reached out on a Wanganui Facebook page for mothers, asking for help to curb her "insatiable cravings" for washing powder, which she developed while pregnant.

The condition of eating unusual substances is known as pica and is not limited to pregnant women. Other cravings include dirt and clay.

For Miss Martin, the cravings came on just before she entered her third trimester.

"It started as just simply smelling laundry powder when I did the laundry throughout the week," the Turakina woman told the Chronicle.

"As the weeks went on, before I knew it I had my nose inside a laundry powder box every time I walked past the laundry room."

Miss Martin eventually began tasting small amounts of washing powder by wetting her finger, dipping it in the box, and putting it in her mouth.

"I chewed the grains between my teeth to kind of get the texture of the powder as well as the taste, and then would spit it out and rinse my mouth out straight away.

"I ate the yellow Surf washing powder first and it was not how my pregnant mind had imagined it tasting in my head ... although even after trying it and knowing how disappointing the taste was when consuming it, I continued to crave it insatiably."

Even though she didn't like the taste, Miss Martin said the scent that stayed in her mouth and nose was "divine".

The cravings to smell and taste washing powder had got to the point where her partner had to keep her away from the cleaning product aisle at the supermarket, "otherwise I literally stand there and just want to smell the different washing powders".

Miss Martin also loves smelling floor cleaners and dishwashing liquids, but has not been tempted to taste them "as of yet".

She has also developed a love for toothpaste and found herself brushing her teeth "numerous" times throughout the day.

"It's honestly so weird.

"I can't wait to give birth so I can go back to having a normal palate."

She has one other child, but did not have any issues during her first pregnancy.

Embarrassed by her "uncontrollable" habit, she turned to Facebook to ask other mothers how to deal with the craving, and was surprised when others made similar confessions. Her partner also told her of a family member who would eat washing powder by the spoonful, and another relative who used to crave the dirt at the bottom of a potato sack.

Miss Martin hoped other pregnant women would not feel "as ashamed" as she initially did if they suffered from the same thing.

Lesley Dixon from the New Zealand College of Midwives said the cravings would be caused by a condition called pica - "craving substances with little or no nutritional value".

Pica occurs both in pregnant and non-pregnant people, and is "relatively uncommon", Dr Dixon said. "People talk about people they know who craved clay or dirt ... that sort of thing.

"Washing powder is another one that people do."

Dr Dixon said it was not known what caused the cravings. Unilever, the company that owns Surf, advised against chewing or eating their washing powder, which contained ingredients that were "not suitable for consumption".