In the Malthusian perception of reproduction the only restriction on the number of births was the number of women that entered matrimony and the age at which they took this step. For the world Malthus lived in this was an adequate description. Given the near absence of methods and appliances for birth control, fertility in the late 18th and early 19th centuries was indeed determined primarily by the length of time fecund women were at risk of conceiving: that is, the years between approximately 15 and 50 lived as a married woman. The result was, in Louis Henry's terminology, ‘natural’ fertility, fertility uninfluenced by parity, the number of children already born to a couple, or by a target family size. Still, the evidence from empirical studies informs us that natural fertility was not the same in every society. Even in populations not deliberately controlling fertility, the range of number of births was large. Henry himself pointed to the fact that the differences were caused by behavioral as well as biological variables.

This chapter first presents the demographic characteristics of marital fertility. We will compare the age specific marital fertility of Nijmegen and Lugang. Next, we try to understand the differences found by presenting the determinants of fertility. An assessment of differential fecundability proves to be very informative. Post-partum non-susceptibility is the next determinant identified in many studies. Final parity, then, is also dependent on the average birth intervals and on the age at which women stopped having children. The variables gathered upto this point allow us to calculate the expected number of children ever born to a woman. In this way, the theoretical fertility of the age specific marital fertility is replaced by a measure more appropriate to the reality described. All this amounts to deconstructing general marital fertility in its composing parts. The causes behind the differential fertility of Lugang and Nijmegen, and the possible change in these differences are dealt with in a multivariate analysis. At this point the socio-economic and socio-cultural variables are also introduced.

Age Specific Marital Fertility and Total Marital Fertility Rate

Before dealing with the factors responsible for the variation in ‘natural’ fertility we will first turn to an often used general measure of fertility in our two towns, the age specific marital fertility (asmf).