A probability model applicable to the study of inter-live birth intervals and random segments of the same

Abstract This paper deals with an analytical study of two types of birth intervals, viz. 'closed intervals' and 'open intervals' through the application of simple probability theory. The 'closed interval' stands for the time interval between two successive live births of a woman, and the 'open interval' denotes the interval between the date of last live birth and the date of survey for a married woman in the reproductive age group surveyed at a point of time. The study considers the 'closed interval' as the sum of independent random variables, each representing a particular component like post-partum amenorrhea, waiting time in the susceptible state, etc. Approximations to the patterns of distributions of these component random variables are made from the available data collected in fertility surveys at Gandhigram. The 'open interval' for any parity is studied separately for two different (mutually exclusive) categories of women, viz. those who have at least one more live birth at some time or other during their reproductive period and those who cease childbearing. In the first case the 'open interval' is considered as a random segment or partition of the corresponding 'closed interval'; in the second as a random segment of the interval between the date of birth of the last child and date at which the woman attains 45 years of age. The mean and variance of the 'open interval' is obtained separately in each case, and the moments of the 'open interval' distribution for women chosen at random from the population are obtained as an appropriate mixture of the two types.     

Some comments on Ursula M. Cowgill's article, 'life and death in the sixteenth century in the city of York' (Population Studies, July 1967)

Abstract The initial purpose of Miss Cowgill's investigation was to study possible differences in mortality according to the season of birth, a study in which groups of people must be followed from birth to death. In the present case the groups were composed of people born in six parishes of the City of York between 1538 and 1601.     

Some comments on ‘the structure of subjective well-being in nine western societies’ by andrews and inglehart

This paper makes a number of critical comments on a recent article by Andrews and Inglehart (1979), where the similarity of subjective well-being data from nine different countries was investigated. It is first shown that different MDS representations can be constructed for the data which differ considerably among each other and with respect to the similarity hypothesis. The goodness of the MDS solutions is discussed by using finer indices than overall Stress. Then, the measures of configurational similarity are evaluated statistically. Finally, it is shown that other, equally valid measures lead to completely different conclusions. It is argued that this poses an insurmountable problem. A facet theoretical approach which looks for prototypical structures rather than a single similarity index avoids this dilemma.     

Frequency and timing of intercourse: Its relation to the probability of conception

Abstract This paper describes a simple study of the chance of conception assuming a fixed-length menstrual cycle, a specific probability distribution for the day of ovulation, and a broad and a narrow fertile period. Eight different patterns of intercourse throughout the cycle are considered with frequency of intercourse ranging between 5 and 12 times per cycle. Results are given in terms of chance of conception and in terms of waiting times until conception.     

Tobacco use in the third trimester of pregnancy and its relationship to birth weight. A prospective study in Spain

BackgroundFew studies have been carried out in Spain examining the use of tobacco amongst expectant mothers and its effect on birth weight.AimsTo observe the proportion of expectant mothers who smoke during their pregnancy, and the impact of tobacco consumption on maternal and birth weight. We also aimed to identify the trimester of pregnancy in which tobacco use produced the greatest reduction in birth weight.MethodsProspective observational study in Spain. A random sampling strategy was used to select health centres and participant women. A total of 137 individuals were enrolled in the study. Exposure to tobacco was measured through a self-reported questionnaire. Regressions were performed to obtain a predictive model for birth weight related to smoking.FindingsOverall, 35% of study participants were smokers during the pre-gestational period (27% in the first trimester, 21.9% in the second and 21.2% in the third). 38.7% of smoking cessation attempts took place in the third-trimester. Pregnant women who smoked up to the third trimester had a higher risk of giving birth to a baby under 3000 g, compared to non-smokers (OR = 5.94, CI 95%: 1.94–18.16). Each additional unit of tobacco consumed daily in the 3rd trimester led to a 32 g reduction in birth weight.ConclusionAn important proportion of pregnant women in Spain smoke during pregnancy. Pregnant women exposed to tobacco have newborns with lower birth weight. Smoking during the 3rd trimester of pregnancy is associated with the greatest risk of lower birth weight.     

The pill and partnerships: the impact of the birth control pill on cohabitation

This paper investigates the impact on cohabitation behavior of the introduction and dispersion of the birth control pill in the USA during the 1960s and early 1970s. A theoretical model generates several predictions that are tested using the first wave of the National Survey of Families and Households. Empirically, the causal effect is identified by exploiting plausibly exogenous variation in state laws granting access to the pill to unmarried women under age 21. The evidence shows that the pill was a catalyst that increased cohabitation??s role in selecting marriage partners, but did little in the short run to promote cohabitation as a substitute for marriage.     

The effects of child-related benefits and pensions on fertility by birth order: A test on Hungarian data

Using aggregate time-series data from post-war Hungary, we investigated the effect of child-related benefits and pensions on overall fertility and fertility by birth order. The results indicate moderate effects that are robust across a wide range of specifications. According to our estimates, a 1-per-cent increase in child-related benefits would increase total fertility by 0.2 per cent, while the same increase in pensions would decrease fertility by 0.2 per cent. The magnitude of both effects increases by birth order; this is more robust for child-related benefits.     

Life course events and residential change: unpacking age effects on the probability of moving

We know that life course events, especially divorce and separation, trigger residential moves, but we know less about how these and other life course events intersect with how far people move and the relationship with labour market change. This research uses data from the Household, Income and Labour Dynamics Survey in Australia to model a set of life course events and their intersection with the distance of move. I examine essentially positive events, marriage and new births and not so positive events, separation and divorce, and the unexpected events of widowhood and job loss, and their outcomes in the housing market. For the decision to move, the models partly parallel other studies of life course events and their role in the mobility decision, but the results provide enriched results about how age and life course events intersect. The analysis shows in greater detail how age acts as a proxy for complicated life course intersections with moving. The disruption of divorce and separation, as expected, increases the probability of moving but with different effects over distance. Households move in response to these life events but they are much less likely to change metropolitan locations, which reflects the embedded nature of family change and location. Overall, the research enriches previous studies of age-related links to migration and mobility.     

Response to Guttman & Levy's article ‘on the definition and varieties of attitude and wellbeing’

Guttman and Levy have prepared an extravagant critique focused mainly on the 1980 Andrews-McKennell article in this journal. The clearly stated purpose of that article was to report a “series of explorations into the affective and cognitive components of some of the more widely used measures of perceived well-being”. Guttman and Levy ignore this. They proceed on the mistaken impression that we were (or perhaps should have been) embarking upon a definitional exercise to relate the concepts of attitude and wellbeing. Yet the reason we did not cite their article on that topic was precisely because it did not address in a direct or focused way the topic that concerned us. Their critique consists of an entirely irrelevant reanalysis of some attitudinal data by Ostrom, together with a tissue of recondite definitional and methodological issues of little consequence either for the objectives or the conclusions of our research. Their dismissal of our work as ‘scientific retrogression’ rests on an a priori definition of science that fits their own methodological style but excludes that of many other prominent researchers. Their comments reflect an attempt at methodological imperialism. We defend our independence — and that of other investigators — to use promising new methodologies other than the particular approach advocated by Guttman and Levy. (Their denunciation of the new methods of structural equation modeling is not shared even by the authoritative reviewer they themselves quote.) In addition to Guttman and Levy's specific criticisms, our Response addresses general methodological issues such as the status of structural modeling and the testing of structural models. In a concluding section we identify areas that merit further research.     

Investigation on birth desires of couples of childbearing age in Hongsheng and three other villages conforming to consideration conditions for the second birth]

The opinions of inhabitants of outlying rural areas regarding second births are explored in this report. By means of household interviews, it is revealed that 22 households out of 153 (i.e., 14.4%) that are eligible for a second birth usually do not opt for the second birth. In a study that took place in four villages within one county, findings showed that desire for a second birth is determined in large part by the sex of the firstborn, males being preferred to females. Moreover, this desire decreases in proportion to time in that the elegible married couple often realizes the economic benefit of having only one child after the first child's birth and chooses not to have a second one. Similarly, many low-income couples would like to have a second child but find that it is not within their economic means. Mid-range income couples often want a second child as well. However, it is generally the couples with higher income that choose to remain with only one child. The desire for a male child is quite strong in the People's Republic of China, especially in rural areas. The fact that the male carries on the family name is very important in most people's opinion, as is the fact that a son has the potential to increase the family's income through manual labor. Thus, the inhabitants of rural areas traditionally favor male children.     

Birth order matters: the effect of family size and birth order on educational attainment

Using the British Household Panel Survey, we investigate if family size and birth order affect children’s subsequent educational attainment. Theory suggests a trade-off between child quantity and “quality” and that siblings are unlikely to receive equal shares of parental resources devoted to children’s education. We construct a new birth order index that effectively purges family size from birth order and use this to test if siblings are assigned equal shares in the family’s educational resources. We find that the shares are decreasing with birth order. Ceteris paribus, children from larger families have less education, and the family size effect does not vanish when we control for birth order. These findings are robust to numerous specification checks.

Using the Pao as the primary sampling unit. Some notes and reflections on the possibilities of a census of China by sampling

Recently sample surveys of the population have been taken in Greece and the United States. In this paper the author considers how far the methods adopted in these two sample surveys may be applied to a study of the Chinese population. In particular, the pao-chia system of administration would make it possible to have a sampling scheme in which the pao (or district) would be the primary sampling unit. A sampling scheme of this kind has been worked out and is presented at the end of the paper.     

Some remarks on the paper by A. Okore, 'Rural-urban fertility differentials in Southern Nigeria: An assessment of some available evidence'

Abstract In his paper Okore(1) critically examines the view of Olusanya and Ekanem that, partly because of shorter periods of breastfeeding and abstinence associated with 'modernization', urban fertility exceeds rural. Unfortunately, the proponents of this view have produced very few hard data on durations of breast-feeding and abstinence.(2).     

The influence and meaning of the birth environment for nulliparous women at a hospital-based labour ward in Sweden: An ethnographic study

BackgroundLabour and birth are sensitive physiological processes substantially influenced by environmental and psychosocial factors.AimTo explore the influence and meaning of the birth environment for nulliparous women giving birth in either one of two differently designed birthing rooms at a hospital-based labour ward.MethodsFive months of ethnographic fieldwork was conducted at a labour ward in Sweden, consisting of participant observations of 16 nulliparous women giving birth in either a ‘Regular’ birthing room (n = 8) or a specially designed, ‘New room’ (n = 8). Data included field notes, informal interviews, reflective notes, and individual interviews with eight women after birth. The data was analysed through an ethnographic iterative hermeneutic analysis process.FindingsThe analysis identified the birth environment as consisting of the physical space, the human interaction within it, and the institutional context. The analytic concept; Birth Manual was conceived as an instrument for managing labour in accordance with institutional authority. Significant to the interpretation of the influence and meaning of the birth environment were two abstract rooms: an Institutional room, where birth was approached as a critical event, designating birthing women as passive; and a Personal room, where birth was approached as a physiological event in which women’s agency was facilitated.ConclusionInstitutional authority permeated the atmosphere within the birth environment, irrespective of the design of the room. A power imbalance between institutional demands and birthing women’s needs was identified, emphasising the vital role the birth philosophy plays in creating safe birth environments that increase women’s sense of agency.     

Taking the reins: A grounded theory study of women's experiences of negotiating water immersion for labour and birth after a previous caesarean section

BackgroundWomen seeking a vaginal birth after a caesarean section (VBAC) frequently want to keep their subsequent labour and birth free from intervention. Water immersion (WI) during labour is potentially an effective tool for women having a VBAC for its natural pain-relieving properties. However, negotiating access to WI can be difficult, especially in the context of VBAC.AimTo explore women's experiences of negotiating WI for labour and birth in the context of VBAC.MethodologyThis Grounded Theory study followed Strauss and Corbin's framework and analytic process. Twenty-five women planning or using WI for their VBAC labour or birth were recruited from two midwifery practices and a social media group across Australia. Participants were interviewed during pregnancy and/or postnatally.Findings‘Taking the reins’, the core category explaining the women’s experiences of assuming authority over their birth, comprised five categories: ‘Robbed of my previous birth experience’; ‘My eyes were opened’; ‘Water is my tool for a successful VBAC’; ‘Actioning my choices and rights for WI’, and ‘Empowered to take back control’. ‘Wanting natural and normal’ was the driving force behind women’s desire to birth vaginally. Two mediating factors: Having someone in your corner and Rules for birth facilitated or hindered their birth choices, respectively.ConclusionThe women became active participants in their healthcare by seeking information and options to keep their birth experience natural and normal. Support from other women and advocacy in the form of continuity of midwifery care was crucial in successfully negotiating WI for their VBAC when navigating the complex health system.