On the duration of pregnancy and the calculation of the date of confinement : is Dr. Wm. Harvey or Dr. Wm. Montgomery in the right? / by J. Matthews Duncan.

  • James Matthews Duncan
Date:
[1856]
Catalogue details

Licence: Public Domain Mark

Credit: On the duration of pregnancy and the calculation of the date of confinement : is Dr. Wm. Harvey or Dr. Wm. Montgomery in the right? / by J. Matthews Duncan. Source: Wellcome Collection.

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    day are not given. In an exact investigation like this, all cases should be rejected except those dating from a single coitus or coitus on a single day. But let us examine and see what this table affords towards the solution of our question. Omitting six cases where a single day is not given, we have fifty where the interval between fruitful intercourse and parturition is said to be as follows:—242, 258, 258, 263, 265, 267, 267, 267, 267, 268, 269, 269, 272, 273, 273, 274, 274, 275, 275, 276, 277, 277, 278, 278, 279, 279, 279, 279, 279, 280, 280, 280, 280, 281, 283, 283, 284, 285, 286, 287, 287, 287, 288, 290, 291, 291, 292, 293, 293, 297. Of these fifty cases, all those satisfactorily known to Dr Montgomery, the mean duration is 277 days. This table, framed under the conditions above de¬ scribed, yields a result opposed to the dogma of its author. Where, then, is the authority for stating 280 days as the natural period of gestation I It is nowhere. We agree with Dr Montgomery in his opinion that there is no other satisfactory method of arriving at the solution of this question, but the one we have just followed, viz,, the collection of well ascer¬ tained facts and their analysis. Independently (says he) of the very few cases in which we have satisfactory evidence of conception following casual intercourse, or perhaps a single coitus, we have no certain means of knowing exactly the commencement of gestation, and are obliged to form our calculation on one or other of three very fallacious grounds; ” which he then proceeds to consider. The Calculation of the Day of Confinement. In the vast majority of cases, this must be made from the termina¬ tion of the last menstruation, for reasons which are well known. The average time to which a woman goes, after the last appearance of the menses is 278 days (a period shorter than Dr Montgomery’s duration of pregnancy!). This average is obtained by the collec¬ tion of single observations and their subsequent analysis. If, then, we wish to ascertain the most probable day of a woman’s confine¬ ment, we add 278 days to the last day of the last menstruation. The method of doing this, without a periodoscope, I have shown in the Mo7itMy Journal for March 1854. Dr Montgomery gives no specific directions for making this im¬ portant calculation. But, it appears, from some passages occurring incidentally in his essay, that he adopts the following plan. Some day is selected after last menstruation, as the most probable day of fruitful intercourse, and 280 days are added thereto. As the selec¬ tion of this day must be, in almost every case, made on the most wortliless and insufficient grounds, the resulting calculation must be similarly characterized. Besides, if there be any truth in the statistical data of Dr Montgomery, and their analysis given above, which is partly his own, then this plan of his must lead to a putting off of the probable day of confinement to far too distant a time. For nstance, we have in the table of observations dated from the day of
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