unfatiguing occupations of milliners, etc., rest during pregnancy
still remains important, and cannot safely be dispensed with.
"Society," Letourneux concludes, "must guarantee rest to women
not well off during a part of pregnancy. It will be repaid the
cost of doing so by the increased vigor of the children thus
produced" (Letourneux, _De l'Influence de la Profession de la
Mère sur le Poids de l'Enfant_, Thèse de Paris, 1897).

Dr. Dweira-Bernson (_Revue Pratique d'Obstétrique et de
Pédiatrie_, 1903, p. 370), compared four groups of pregnant women
(servants with light work, servants with heavy work, farm girls,
dressmakers) who rested for three months before confinement with
four groups similarly composed who took no rest before
confinement. In every group he found that the difference in the
average weight of the child was markedly in favor of the women
who rested, and it was notable that the greatest difference was
found in the case of the farm girls who were probably the most
robust and also the hardest worked.

The usual time of gestation ranges between 274 and 280 days (or
280 to 290 days from the last menstrual period), and occasionally
a few days longer, though there is dispute as to the length of
the extreme limit, which some authorities would extend to 300
days, or even to 320 days (Pinard, in Richet's _Dictionnaire de
Physiologie_, vol. vii, pp. 150-162; Taylor, _Medical
Jurisprudence_, fifth edition, pp. 44, 98 et seq.; L.M. Allen,
"Prolonged Gestation," _American Journal Obstetrics_, April,
1907). It is possible, as Müller suggested in 1898 in a Thèse de
Nancy, that civilization tends to shorten the period of
gestation, and that in earlier ages it was longer than it is now.