Previous studies on prefectural differentials in fertility argued that the period marital fertility in Tokyo is at the same level as that of total Japan via standardization or decomposition using age-specific marital fertility rates. We have argued, however, that period marital fertility should be measured by cumulative marital fertility rates and that age-specific marital fertility rates sometimes show the different trend from that of the cumulative marital fertility rate. We have proposed a measure to indicate period cumulative marital fertility: i.e. ever-married fertility rate defined as total fertility rate divided by total first marriage rate, which reflects the fact that the Japanese fertility is markedly influenced by marriage occurrence.
In terms of period marital fertility, we showed that the ever-married total fertility in Tokyo (1.79 in 1985 and 1.58 in 1990) was the lowest (totals Japan: 2.13 and 1.97 in those years). Also, we showed the total marital fertility rate in Tokyo was 1.876 whereas that in total Japan was 1.997 in 1982-1986 using the data of the ninth National Fertility Survey in 1987. Thus, we conclude that the recent period marital fertility in Tokyo was lower than that in total Japan. Previous studies considered the high proportion never-married as a factor lowering fertility in Tokyo, inferring relatively high marital fertility. On the contrary, we clarified that the high proportions never-married in Tokyo produces relatively high occurrence of first marriage counteracting the lower marital fertility.
Concerning ever-born fertility by prefecture, we analyzed the number of own children of females aged 35-39 by the 1990 Census which we use as a proxy of cohort completed fertility. The main results are as follows.
(1) Both fertility and ever-married fertility are the lowest in large metropolitan prefectures such as Tokyo and Osaka, and so is proportion ever married, though the low proportion ever-married is also found in some local prefectures such as Okinawa.
The difference in fertility in Tokyo from total Japan (-0.286) is attributable to the difference in proportion ever-married (-46.3%) and to that in ever-married fertility (-53.7%).
(2) The differences in fertility of employed women in the large metropolitan prefectures from that of total Japan are larger than the differences of non-employed women. The differences in fertility of employed women in Tokyo from that among employed women of total Japan (-0.436) is attributable to the difference in proportion ever-married (-52.0%) and to that in ever-married fertility (-48.0%).
The difference in fertility in Tokyo from total Japan (-0.286) is also attributable to the differences in the proportion-employed (7.296), in employed fertility (-85.0%) and in non-employed fertility (-20.3%).
(3) The proportion ever married among women aged 35-39 years in Tokyo is the lowest, though the lowest proportions are also observed in some of the local prefectures such as Okinawa. The difference in the proportion ever-married in Tokyo from total Japan (-0.0768) is attributable to the differences in the proportion employed (8.5%), in the proportion ever-married among the employed (-101.4%) and in the proportion ever-married among the non-employed (-3.3%).
(4) The proportions employed among ever-married women aged 35-39 in metropolitan prefectures are the lowest in Japan and, on the contrary, the proportions employed among never married there are the highest.
(5) The proportions of zero parity among ever-married women aged 35-39 years in metropolitan prefectures are the highest in Japan, and the proportions of parity three and more there are the lowest.
The proportions employed among ever-married women aged 35-39 by parity in metropolitan prefectures are all the lowest, which means that the wives in metropolitan prefectures have the largest difficulties to work outside home if they have children and that, even if they have no children, they are least likely to be employed.
In conclusion, the lowest completed fertility in metropolitan prefectures is not due to the employment rate itself but due to the lowest proportion married and the lowest marital fertility among employed women. The reduced fertility, proportion married and marital fertility in those prefectures are assumable caused by the environment peculiar to metropolitan prefectures in respect to childbearing, child rearing and marriage such as hard working condition, housing, childcare and child education.