Chapter XXV: Appendix: C

SUGGESTIONS FOR CALCULATING THE DATE OF ANTICIPATED BIRTH

The leading authority in the _Manual of Human Embryology_, edited by Franz Keibel and Franklin P. Mall in two volumes, London, 1910, says:--

“In ancient times it was generally believed that the duration
of pregnancy in man, unlike that in lower animals, was of very
uncertain length; and it was not until the seventeenth century that
it was more accurately fixed, by Fidele of Palermo, at forty weeks,
counting from the last menstrual period. In the next century Haller
found that if pregnancy is reckoned from the time of a fruitful
copulation it is usually thirty-nine weeks, and rarely forty weeks
in duration. In general these results are fully confirmed by the
thousands of careful data collected during the nineteenth century.”

* * * * *

“However, from thousands of records it is found that the mean
duration of a pregnancy varies in first and second pregnancies, is
more protracted in healthy women, in married women, in winter, and
in the upper classes.”

* * * * *

“From these figures it is seen that most pregnancies take place
during the first week after menstruation, and that the duration
of pregnancy is longer if copulation takes place towards the end
of the intermenstrual period. And this is explained if we assume
that in the first week, especially the first few days after the
cessation of menstruation, the ovum is in the upper end of the
tube awaiting the sperm and that conception immediately follows
copulation. When the fruitful copulation takes place in the latter
two weeks of the month the opposite is usually the case; the sperm
wanders to the ovary and there awaits the ovum; and, therefore, on
an average, pregnancy is prolonged in this group of cases, when
determined from the time of copulation.”

* * * * *

“In determining the age of human embryos it is probably more
nearly correct to count from the _end_ of the last period, for
all evidence points to that time as the most probable at which
pregnancy takes place.”

On the whole it is generally found that 280 days (_i.e._, 40 weeks) can be reckoned as the average period during which the child develops internally if the date is counted from the first day of the last menstrual period and 269 days if estimated from the date of actual union.

Leuckart tabulated results from a large number of births which took place within the first ten months of marriage, and found that there was a maximum number of births on the 275th day, then a decrease and a second maximum on the 293rd day. Nevertheless, in spite of careful reckoning, there are, as will be recognized, many sources of error, and medical men and nurses are often wisely cautious of giving any exact date for an anticipated birth; sometimes too cautious even to suggest the week within which the birth will take place. I have known a good many mothers, however, who were much more accurately certain about this point than their attendants, and have found that the birth took place exactly on the day they anticipated. As an illustration of this, I give the answer from one of my correspondents, both of whose children were born on the exact day she anticipated. I asked her how she estimated these periods, and she said:--

“I simply took old Dr. Chevasse’s rule which he gives in _Advice to
a Wife_; you know how he puts the date of conception and opposite
it the probable date of birth. I went by the first union after the
last period. It so happened that my husband was seedy and there
was no union for a fortnight after the end of the period. I took
that first union as the date of conception and looking up the date
in Chevasse and the corresponding date of birth opposite, I found
it to be August 20th, and sure enough on August 20th he was born.
With the second boy, the union took place the day after the last
period, and I took that as the starting date and against it I found
January 21st and on January 21st he arrived in spite of the doctors
insisting in each case that it would be three weeks earlier. What I
do is, I always make a mark in my diary against the date of first
union after every period. Then when I had missed a period and so
knew that there was probably conception, I could at once tell the
probable date.”

The table Chevasse quoted from Galabin is as follows--

From Jan. 1st to Oct. 1st = 273 (274) days, add 5 (4) days
„ Feb. 1st to Nov. 1st = 273 (274) „ „ 5 (4) „
„ Mar. 1st to Dec. 1st = 275 „ „ 3 „
„ Apl. 1st to Jan. 1st = 275 „ „ 3 „
„ May 1st to Feb. 1st = 276 „ „ 2 „
„ June 1st to Mar. 1st = 273 (274) „ „ 5 (4) „
„ July 1st to Apl. 1st = 274 (275) „ „ 4 (3) „
„ Aug. 1st to May 1st = 273 (274) „ „ 5 (4) „
„ Sep. 1st to June 1st = 273 (274) „ „ 5 (4) „
„ Oct. 1st to July 1st = 273 (274) „ „ 5 (4) „
„ Nov. 1st to Aug. 1st = 273 (274) „ „ 5 (4) „
„ Dec. 1st to Sep. 1st = 274 (275) „ „ 4 (3) „

_Printed in Great Britain by_
UNWIN BROTHERS, LIMITED, THE GRESHAM PRESS, WOKING AND LONDON

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Transcriber's Note

The following apparent errors have been corrected:

p. 2 "hearts’ desire" changed to "hearts desire"

p. 26 "undertsand" changed to "understand"

p. 73 "incapacities is," changed to "incapacities, is"

p. 124 "diappointments" changed to "diappointments"

p. 130 "parent this" changed to "parent: this"

p. 148 "agggravation" changed to "aggravation"

p. 150 "ffower" changed to "flower"

p. 154 "want to to" changed to "want to"

p. 218 "ignorance" changed to "ignorance."

p. 233 "Franz, Keibel" changed to "Franz Keibel"

The following possible errors have not been changed:

p. 4 millenium

p. 34 co-incidently

p. 132 August 24 1893

p. 235 follows--

The following are used inconsistently in the text:

lifelong and life-long

overstrained and over-strained

prenatal and pre-natal

shamefaced and shame-faced

X-rays, “X” rays and “X”-rays

End of Project Gutenberg's Radiant Motherhood, by Marie Carmichael Stopes