When I use a word…: Oe no!

As chairman of examiners in last year's preclinical examinations I was responsible for drafting the examiners' report. I circulated the first draft to my coexaminers. One of them asked me to change “fetus” to “foetus.”

Fetus derives from the Latin word feto, I breed, but the spelling “foetus” has been around since at least the beginning of the seventh century. St Isidore, Archbishop of Seville, in a section entitled “De homine et partibus eius” in his Originum sive etymologiarum libri (Books of Origins or Etymologies), commonly known as the Etymologiae (published in about 620 AD), incorrectly wrote that it was derived from foveo, I keep warm: “Foetus autem nominatus, quod adhuc in utero foveatur” (XI, 1, 144).

The earliest English language citation in the Oxford English Dictionary (from 1398) uses the spelling “fetus,” and it is not until 1594 that “foetus” is first recorded: “the Foetus of the Latines, and Embryon of the Greekes” (T B la Primaud). All this confused Samuel Johnson. In his dictionary he defined fetus as “Any animal in embryo” and foetus as “The child in the womb after it is perfectly formed; but before, it is called embryo.”

Spelling does not, however, always accord with etymology, and it is wrong to be prescriptive. I prefer “fetus,” but was prepared to capitulate if “foetus” was more commonly used. I therefore searched my computerised database of world bioscience literature since 1966. The results are shown in the table as percentage occurrences of the spelling “fetus” in the titles and abstracts of nearly 25 000 publications containing the word fetus or foetus.

Currently world wide “fetus” is used in 92% of publications, but there are regional variations. Not surprisingly, the figure is close to 100% in United States publications. In contrast, in English language titles and abstracts of non-English language publications the overall current figure is considerably lower (81%) and has been falling since 1966. In Britain, however, and in English language publications elsewhere it is currently as high as 90%, having in both cases increased significantly since 1966–82.

The striking increase in the use of “fetus” in Britain since 1966 is masked by the summary data. From about 1974 the frequency increased linearly to its current level, which it reached in 1985. But before that it was 67% in 1972–4, 42% in 1969–71, and only 17% in 1966-8. On the other hand, perhaps this rapid rise since the late 1960s is not so surprising—in October 1969 the BMJ first started to use “fetus” as its preferred spelling.