Dame Margaret Sparrow writes about the Coca-Cola bottle top on display in Te Papa’s exhibition Contraception: Uncovering the collection of Dame Margaret Sparrow (Illott Room, level 4).

The Coca-Cola flavour was introduced by an American pharmacist in 1886 and sold in bottles from 1894. In 1915 a competition was held for a distinctive bottle which was then patented and launched as a marketing innovation which set Coca-Cola apart from other competitors. Throughout 2015 Coke is celebrating the centenary of the ‘hold in your hand’ bottle in a global marketing campaign.

In the 1950s and 60s, young New Zealanders found it hard to access contraceptives – they couldn’t just buy them off the shelf and doctors were not permissive. In desperation and showing practical improvisation, some women douched with Coca-Cola which seemed fit for the purpose given the shape of the bottle and the powerful fizz to propel the solution into the vagina after intercourse (sometimes referred to as “shake and shoot”).

Was there any basis for this practice? Three researchers from Harvard Medical School looked at the spermicidal properties of Classic Coke, New Coke and Diet Coke and found that indeed they did kill sperm, at least in the laboratory. The most effective was Diet Coke followed by Classic Coke.* However sperm can be found in fertile cervical mucus within 15 seconds of ejaculation so flushing with any sort of douche is not a very effective method of contraception and may even introduce infection. Coke is definitely not recommended for contraceptive purposes.

*Umpierre, S.A., et al. Effect of ‘Coke’ on Sperm Motility. New England Journal of Medicine. November 1985 (p. 1351).