MARYLAND SLAVE POPULATION	47

the oldest child plus nine months from the age of the mother, a rough
estimate of the age at first conception is possible: 18.7 years on the average
for these twenty women. This figure should be considered an upper
bound for the mean age at which native-born women initially conceived.
The first child of several of the women may have died before the inven-
tory was taken. Furthermore, some of the women may have been im-
migrants, although appraisers were more likely to record the ages of
native than of immigrant slaves. Allan Kulikoff, working with a larger
number of observations and in a period when the chances of inflating the
result by including immigrants had fallen, has found a mean age at
initial conception of just over 17 years for slave women appearing in
Prince George's County inventories between 1730 and I750.51

A summary of the argument may prove helpful at this point. The
immigrant slave population possessed several characteristics that tended
to depress the rate of natural increase. African-born slaves suffered from
high rates of mortality and morbidity, an unbalanced sex ratio, and per-
haps an extreme alienation expressed in part as an unwillingness to have
children. Most important, immigrant women were well advanced in their
child-bearing years when they arrived in the colony. As a result, the initial
immigrant population failed to reproduce itself. They did have some chil-
dren, however, and these children transformed the demographic character
of slavery in Maryland. The native-born lived longer and were less sickly
than their immigrant forebears, they were more thoroughly assimilated,
and there was among them a relatively equal ratio of men to women.
Most important, native women began their reproductive careers at a
much younger age than their immigrant mothers. Creole women had
enough children to improve the natural growth rate in the slave popula-
tion despite a continuing heavy black immigration, a still unbalanced
sex ratio, and the apparent failure of their masters to appreciate fully the
benefits of a self-perpetuating labor force.52 Although a good deal of

51 Kulikoff discusses age at first conception along with other aspects of slave
demography in his dissertation. For an example of the nature of the evidence used
to estimate age at conception see Inventories and Accounts, XXXVIC, 223. For
a similar method applied in different circumstances see Peter Laslett, "Age at
Menarche in Europe since the Eighteenth Century," Jour. Interdisciplinary Hist.,
II (1971-1972), 228-234.

52 I should emphasize that I am not arguing that fertility necessarily increased,
but merely that native-born slave women had opportunity for sexual intercourse
in Maryland for a larger proportion of their reproductive lives than did immi-
grants. A finding of constant age-specific fertility rates for native and immigrant
women would not be incompatible with the argument. However, it is likely that