When was the noun 'labour' first used in relation to childbirth?
Royal baby: Duchess of Cambridge goes into labour
BBC TV 23rd April 2018
The first reference I can find that is a reliable use of 'labour' in regard to childbirth is in the King James (Authorised) Bible of 1611:
And they iourneyed from Bethel: and there was but a litle way to come to Ephrath; and Rachel traueiled, and she had hard labour.
Genesis 35:16 Textus Receptus
The OED has a few quotes before that (see below) but they do not seem as clear to me (in relation to childbirth).
However, in 1623 Shakespeare, no doubt influenced by the KJV, uses the noun in relation to childbirth:
Shakespeare & J. Fletcher Henry VIII v. i. 18 The Queens in Labor They say in great Extremity, and fear'd Shee'l with the Labour, end.
And there is a metaphoric use of the noun in 1634:
T. Heywood Maidenhead Lost i. B 3 b My brain's in labour, and must be deliuered Of some new mischeife.
So was it the KJV bible which first used the word 'labour' as a noun in relation to childbirth?
OED references earlier than 1611:
1472 J. Paston in Paston Lett. & Papers (2004) I. 452 God spede yow, and Owre Ladye hyre to hyre plesure, wyth as easye labore to overkom that she is abowt as euyre had any lady or [gentyll]-woman saff Owre Lady heer-selffe. And soo I hope she shall to hyre greet joye and all owres.
?1529 R. Hyrde tr. J. L. Vives Instr. Christen Woman sig. Kivv Wherfore she was worthy to beare a chylde with great payne and werynes: and in her labour to be delyuered of her chyde [sic] and her lyfe both.
1580 T. Newton Approoued Med. f. 84 v In the tyme of the byrthe & labour bounde to the Leage, it bryngeth forthe the chylde wythout payne.
1595 Spenser Epithalamion in Amoretti & Epithalamion xxi. sig. H6 Sith of wemens labours thou hast charge, And generation goodly dost enlarge.
The 1472 OED quote definitely refers to childbirth. The quote is from one in a series of letters (known as the Paston Letters). More context makes it clear the author (John Paston, although I'm not sure which one) is referring to "his lady":
And wheer ye goo to my laydy off Norffolkys and wyll be theere att the takyng off hyre chambre, I praye God spede yow, and Owre Ladye hyre to hyre plesure, wyth as easye labore to overkom that she is abowt as euyre had any lady or gentyll-woman saff Owre Lady heer-selffe
A little later in that series, apparently later the same month, he writes that his lady is "with child":
As for the lettyrs that Slyfeld shold get newe of the Kyng, whyche ye shold bryng to my lord of Norffolk, it is myn avyse that ye shall come home your-sylff as hastyly as ye maye so that ye may be at the crystenyng of the chyld that my lady is wyth.
However, the association of the word "labor" with childbirth is older than that quote. I think that "labor" in the childbirth sense comes (at least in part) from this definition (from Middle English):
4 (b) pain, sickness, disease; also, the active phase of an intermittent disease; ~ of birthe
MED
Although I can't find the full text, here's an example of "labor of birth":
In soda when it is grete and at vomite..& crying and labour of birth.
The Middle English Translation of Guy de Chauliac's Grande Chirurgie (?a1425)
Another quote talks about the "labor she had in childing" (where "childing" means childbirth):
And aftyr that sche had conceyved, sche was labowrd wyth grett accessys tyl the chyld was born and than, what for labowr sche had in chyldyng and for sekenesse goyng beforn, sche dyspered of hyr lyfe, wenyng sche mygth not levyn.
The Book of Margery Kempe (a1438)
The verb "labor" also has had the following definition since Middle English:
3(a) To endure pain, suffer; ~ of child, be in labor
MED
And here is an example:
Mor over, in augmentyng of my sorwe, I wend my wif shuld a dyed sith, for aftir she was arestid she laboured of hir child, that she is with all, waityng either to dye or be delyvered, and she hath not gon viij. weks quykke.
What's significant about the above quotation is that it's also from the Paston Letters collection, albeit much earlier (1454) and by a different author (Thomas Denyes) to one of the John Pastons (I think this one, father to the John Paston that wrote the 1472 quote).