流动人口女性个体的生育间隔影响因素研究——基于2016年全国流动人口动态监测调查数据

本文采用2016年全国流动人口动态监测调查数据,运用半参数Cox回归对我国流动人口的生育间隔进行分析。结果发现：第一,不仅人口流动会延迟女性的生育时间,而且受教育水平的提高对女性的婚育间隔、第一次生育间隔均有显著的延迟效应。第二,结婚年龄越大,婚后越有可能选择尽早生育,且不同初婚时间对生育间隔的影响差异明显。同时,参加医疗保险对婚育间隔存在显著的缩短效应,而参加生育保险对生育间隔存在显著的延迟效应。越有经济实力以及在工作中担任重要职位的女性越有可能扩大生育间隔;而随着婚育间隔的扩大,第一次生育间隔反而会缩短。第三,初育子女的性别对第一次生育间隔的影响存在显著差异,即若初次生育为女性,则第一次生育间隔会缩短。第四,根据生育政策效果分析发现,放开生育政策虽无法促使女性缩短婚育间隔,但会明显缩短第一次生育间隔。     

Differentiation of female fertility by educational attainment

The author examines fertility differentials by educational attainment for Polish women using official vital statistics on births as modified in 1974. Comparisons are made with fertility recorded in previous studies based on census or sample survey data     

Models of procreative behavior based on the concept of the life cycle

This is the first in a planned series of papers applying path analysis methods to the study of reproductive behavior in rural areas in Poland. Factors considered include total number of births, birth intervals, birth control and abortion, and future fertility intentions. The objective is to examine how the fertility of rural women is affected by various social and economic factors. (SUMMARY IN ENG)     

The sex ratio at birth

Several aspects of the disparity in birth ratio of males over females are discussed including variations among different races, variations by order of birth, by age of the parent, and in multiple births. Avenues of statistical exploration are suggested in an attempt to indicate certain peculiarities in nature. The Negro population in the United States has a sex ratio of 102 males to 100 females as opposed to 105:100 for whites, a highly significant difference. Inferences from these statistics are suggested for study of the sex ratios of mixed unions. The group classified as Mulatto show a lower sex ratio and further analysis of this was suggested including examination of slave records. For the white population sex ratio declines from 106.2 to 102.9 between 1st order and 7th order births. This is highly significant. However, nonwhite determinations were more irregular. Data limitations on sex ratio by age of parent prevented conclusive results. Multiple births among whites show a decline from 105.3 for single live births to 103.2 for twins and 86.1 for all other plural deliveries. Among nonwhites these ratios are 102.3, 99.7, and 102.6 respectively. Further information should be developed using the multiple facts relating to the sex ratio at birth.     

Statistical materials

Official population data for the USSR are presented for 1985 and 1986. Part 1 (pp. 65-72) contains data on capitals of union republics and cities with over one million inhabitants, including population estimates for 1986 and vital statistics for 1985. Part 2 (p. 72) presents population estimates by sex and union republic, 1986. Part 3 (pp. 73-6) presents data on population growth, including birth, death, and natural increase rates, 1984-1985; seasonal distribution of births and deaths; birth order; age-specific birth rates in urban and rural areas and by union republic; marriages; age at marriage; and divorces.     

The analysis of seasonality in births and deaths

"Monthly data on live births and stillbirths and quarterly data on mortality and infant mortality in Poland are analyzed for the period 1983-1985. The aim is to evaluate and compare seasonal fluctuations in these variables in Katowice voivodship and in Poland as a whole. Effects of seasonal factors are estimated separately for males and females and urban-rural areas via a regression model. For births, effects of seasonality are similar in Katowice and Poland, while for deaths significant differences are observed.     

Regional conditions for differentiation of population reproduction in Poland

This study deals with differentials in gross fertility rates and rates of natural population growth by region in Poland. Two models are formulated with the above indicators as dependent variables and the following set of independent variables: population density, percent of nonagricultural population, housing conditions (number of persons per room), percent of population aged 20-29, percent of population aged 65 and over, percent of male population, percent of urban population, percent of population with high school and college education, percent of working women, and percent of married couples. The most significant variables were age 20-29, urban population, working women, sex ratio, and marital status.     

Measurement and analysis of demographic processes: the characteristics of generation

Since it would take too long (100 years) to ascertain all demographic data about a given age group, i.e., all those born in a given year, these data are determined hypothetically by measuring the various characteristics of persons of all ages in a given time period (1-2 years). Also needed is an indicator of the population as a whole; cumulative coefficients are used for this purpose. One of these is the overall coefficient of births, meaning the number of children a women would have over her whole period of fertility if she had the precise number of children at each period in her life as other women of that age. An analogous indicator is used for measuring mortality--the average life expectancy of a person at each stage in his life. The crude coefficient of population reproduction represents the number of girls to which each woman will give birth between the ages of 15 and 50. This has to be corrected by the number of those who will not live to reproductive age. The result is the corrected coefficient of reproduction of the female population. This coefficient is often thought to reflect the population's growth prospects; if less than unity, therefore, the population will not reproduce itself. This is an incorrect interpretation. The impact of immigration and emigration on the population must also be incorportated. In addition to the above hypothetical indicators, we must also develop real population indicators. Techniques must also be employed to evaluate the reliability of these demographic indicators.     

Births in remarriages (using data from sample surveys)

Data from sample surveys conducted between 1978 and 1981 are used to examine the fertility of women in second and subsequent marriages in the USSR. The results indicate that women up to age 25 who have been married more than once have higher fertility than women in a first marriage. However, total fertility is higher for women in uninterrupted marriages. The analysis is presented separately for various cohorts and for socioeconomic characteristics such as educational status and rural or urban residence.     

Seasonal daily effect on the number of births in Israel

Previous studies have observed a 7-day cycle with the least number of births occurring on Sundays. This study was aimed at characterizing the daily effect on the number of births in Israel, where Sunday is a regular working day and Saturday is a nonworking day. It was hypothesized that fewer births would be noted on Saturday rather than Sunday and fewer births on Jewish holidays. The data consisted of a random sample of live births during 1975. A robust time series procedure was used for the data analysis. As expected, the number of births was much smaller on Saturdays than on other weekdays (10% reduction). The seasonal component for Sundays was greater than that for any other day due to births delayed from Saturday and scheduled induced births. The number of births was not reduced as much on Saturdays during spring and summer as during fall and winter. In addition, fewer births occurred on most Jewish holidays. However, an unexpected and extremely high number of births was noted on Yom Kippur and the day after. It is speculated that the strain and fasting during this holiday promoted labor induction. In 21 of the 52 weeks in the study period, the least number of births occurred on a Saturday, and the number of births was less than the mean of the remaining 6 days in 46 of these weeks. Similarly, in 17 of the 52 weeks, the greatest number of births occurred on a Sunday, and the Sunday births exceeded the mean of Monday-Friday births in 35 of these weeks. Thus, these results confirm the study hypothesis and are believed to reflect intervention in childbirth.     

Why is the number of births increasing?

The author examines whether the unexpectedly high number of births recorded in Poland in 1982 and 1983 is evidence of a change in fertility patterns. It is suggested that the increase in the gross reproduction rate that occurred was due to lower standards of living and fewer opportunities to acquire material possessions or travel abroad as an alternative to having children. Some of the increase may also be due to new pro-natalist measures such as prolongation of paid leave of absence for mothers. The author suggests that the increase in fertility is temporary and that fertility will soon decline to its former level.     

Truncation effect in closed and open birth interval data

A numerical investigation using a flexible simulation model to establish interval analysis as an index for changing natality patterns. Such an index should reflect parity distribution, the age at which women start reproduction, and the spacing of their births. The simulated statistical results illustrate the truncation effect that reflects a negative correlation between parity and the length of closed and open intervals in a birth or marriage cohort. Truncation is related to the duration of marriage at survey, but this duration interacts with other assumptions. Holding duration constant does not ensure that the data on intervals will reflect postulated changes in the distributions. For complete birth orders, this analysis does reflect patterns of child spacing. However, it ignores changes in the parity distribution, whether produced by deliberate limitation of family size or by the onset of secondary sterility. This difficulty is not overcome by life table analysis except under highly restrictive assumptions. It is doubtful whether the current emphasis on securing such data is justified. Further investigation is needed to provide a better basis for the definition and analysis of interval data if they are to be used.     

Women's opinion concerning methods of birth control

Polish women's attitudes toward methods of birth control are compared using data from a survey undertaken in 1985 among newly married women and women married for at least 12 years. The results show that of the women who have been married longer, more are opposed to all methods of family planning, although fewer women in this group approve of natural family planning methods only.     

A NOTE ON THE DEMOGRAPHIC IMPACT OF CONTRACEPTION IN A MATHEMATICAL MODEL OF HUMAN REPRODUCTION

The application of mathematical models of human reproduction to the study of reproductive behaviour as a function of contraceptive behaviour was pioneered by Perrin and Sheps (1963). More recent work in this area continues to focus on an examination of the birth rate as the principal dependent variable. This note suggests an alternative procedure for studying the demographic impact of contraception through the analysis of birth intervals. A mathematical model is formulated for the waiting time between successive live births, and a procedure is described for incorporating into the model certain contraceptive parameters. A controlled experiment is then performed to determine the effect of these parameters on expected child spacing patterns.     

Socio-demographic interests of the population during the transition to a market economy

These are the results of a 1971 survey on reproductive behavior in the former Soviet Union. The survey covered 3,152 women aged 16 or over living in rural or urban areas. Questions were included on ideal, desired, and expected number of children. The results indicate that low fertility expectations characterize the majority of the population and that current political and economic problems are likely to push expected fertility even lower. Significant differences between rural and urban populations and among regions are identified.     

A note on a transient queuing system of a linear birth–immigration process in presence of twin births

In this article, we consider a simple transient queuing system, i.e., a linear birth process with immigration in the presence of twin births. We find the differential-difference equation and also the probability-generating function (p.g.f.) for this process. Again, we generalize it into a linear birth process with immigration in the presence of both single birth or twin births and again for the case of multiple births. From the p.g.f. of linear birth process with immigration in the presence of twin births, we find some particular transient queuing processes like linear birth process with twin births and simple immigration process. Direct derivations of mean and variance of these processes are also discussed without using the generating functions.     

On the eve of birth control. II

The results of a 1981 sample survey on family planning in Poland show that the average birth ratio for couples married in 1975 is 2.1 (2.0 in the cities and 2.5 in rural areas). With a much lower mortality rate, this minimal reproduction ratio still provides the fairly high natural population growth which is characteristic of all industrialized nations. This birth ratio is maintained by almost universal use of various birth control methods after 6-7 years of marriage, i.e., an average family with 2 children is planned and created by means of contraceptives and abortions. The family planning situation in Poland is discussed for women who: 1) plan to have more children, 2) might change their decision not to have more children, and 3) made a final decision not to have more children. The reasons for these decisions are thoroughly analyzed. Particular attention is paid to the extent to which couples are able to reach their reproductive objectives. The analysis indicates that many couples would have had more children if the husband received a higher salary, housing conditions were better, and the mother could quit her job for at least some period of time. Birth control is used because most couples are satisfied with having 2 children and consider their reproductive objectives fulfilled.     

The dynamics and differentials of fertility in the USSR (survey results)

The results of a fertility survey carried out in the USSR in 1978 are presented. The survey included 33,076 women aged 18 to 59. Data are included on fertility rates by region and Union Republic and by urban or rural area, and on expected fertility of women aged 18 to 44. Changes in actual and desired fertility over time are compared for five-year periods from 1945 to 1978. Differences in fertility are analyzed by type of settlement, educational status, and nationality.     

Modeling low birth weights using threshold regression: results for U. S. birth data

Babies born live under 2,500 g or with a gestational age under 37 weeks are often inadequately developed and have elevated risks of infant mortality, congenital malformations, mental retardation, and other physical and neurological impairments. In this paper, we model birth weight as a first hitting time (FHT) of a birthing boundary in a Wiener process representing fetal development. We associate the parameters of the process and boundary with covariates describing maternal characteristics and the birthing environment using a relatively new regression methodology called threshold regression. Two FHT models for birth weight are developed. One is a mixture model and the other a competing risks model. These models are tested in a case demonstration using a 4%-systematic sample of the more than four million live births in the United States in 2002. An extensive data set for these births was provided by the National Center for Health Statistics. The focus of this paper is on the conceptual framework, models and methodology. A full empirical study is deferred to a later occasion.     

THE CASE FOR PARITY AND BIRTH-ORDER STATISTICS

Parity refers to the number of (live) births that a woman (or man) has had. Birth order refers to whether a birth is the first, second, third or higher‐order birth of the parent. In the context of low and shifting fertility, parity and birth‐order statistics are becoming increasingly important for understanding fertility trends and patterns, for policy, and for carrying out projections of future fertility. In Australia, the main sources of demographic data are birth, death and marriage registers, and the five‐yearly national census. Both the birth registers and the census are ideally placed to collect data required to calculate parity and birth‐order statistics. However not all Australian states and territories collect or code the necessary information in the birth registers, and the parity question ‘For each female, how many babies has she ever had?’ is only asked every second census; that is, once every 10 years. In this paper, we outline the importance and uses of parity and birth‐order statistics. We discuss the Australian data available at present and their gaps and shortcomings. We then describe the ‘gold standard’ of parity and birth‐order statistics and how Australia can achieve this standard through some minor changes to the data collection process.