Reactions to Blake and Das Gupta’s “the fallacy of the five million women: A re-estimate”

This article reviews the methods used by Blake and Das Gupta (1972) to estimate need for contraceptive protection among single (never-married) and previously married women below the near-poverty line in 1966. More recent data than those used by Blake and Das Gupta to estimate coital activity and protection by contraception allow calculation of alternative estimates of the number of single and previously married women in need in 1966. To assess the relative accuracy of the two estimates, we introduce a validity check. Using vital data from the National Natality Survey and other sources, we calculate a birth rate and a pregnancy rate for low-income single and previously married women, using the two estimates of the number of women in need—i.e., the population at risk of these vital events. If the two estimates of the number in need of contraceptive protection are either excessively low or high, this should be apparent in the resulting birth and pregnancy rates.     

Marital Shopping and Epidemic AIDS

HIV risks decline sharply at age 30 for women in South Africa, long before coital frequencies or pregnancies decrease. I evaluate several prominent behavioral models of HIV, and find that these do not suggest sharply decreasing risks with age. I formulate a model of spousal search and find that “marital shopping” can generate epidemic HIV prevalence despite low transmission rates because search behavior interacts with dynamics of HIV infectiousness. The implied age-infection profile closely mimics that in South Africa, and the suggested behavior matches that reported by South Africans. Condom use in new relationships and transmission rate reductions are both found to be effective policies and, when used together, eliminate the potential of spousal search to spread HIV. In contrast, antiretroviral treatment is found to have only a minimal effect on the epidemic.     

The Impact of State Abortion Policies on Teen Pregnancy Rates

The availability of abortion provides insurance against unwanted pregnancies since abortion is the only birth control method which allows women to avoid an unwanted birth once they are pregnant. Restrictive state abortion policies, which increase the cost of obtaining an abortion, may increase women’s incentive to alter their pregnancy avoidance behavior, thereby reducing the likelihood of unwanted pregnancies. This study, using state-level data for the years 1982, 1992, and 2000, examines the impact of restrictive state abortion laws on teen pregnancy rates. The empirical results indicate that the price of an abortion, Medicaid funding restrictions, and informed consent laws reduce teen, minor teen and non-minor teen pregnancy rates. The empirical results suggest that these abortion policy restrictions affect the unprotected sexual activity of teens resulting in fewer unwanted teen pregnancies.     

Polygyny, Partnership Concurrency, and HIV Transmission in Sub-Saharan Africa

We study the relationship between polygyny and HIV infection using nationally representative survey data with linked serostatus information from 20 African countries. Our results indicate that junior wives in polygynous unions are more likely to be HIV positive than spouses of monogamous men, but also that HIV prevalence is lower in populations with more polygyny. With these results in mind, we investigate four explanations for the contrasting individual- and ecological-level associations. These relate to (1) the adverse selection of HIV-positive women into polygynous unions, (2) the sexual network structure characteristic of polygyny, (3) the relatively low coital frequency in conjugal dyads of polygynous marriages (coital dilution), and (4) the restricted access to sexual partners for younger men in populations where polygynous men presumably monopolize the women in their community (monopolizing polygynists). We find evidence for some of these mechanisms, and together they support the proposition that polygynous marriage systems impede the spread of HIV. We relate these results to the debate about partnership concurrency as a primary behavioral driver for the fast propagation of HIV in some parts of sub-Saharan Africa.     

Non-Heterosexuality,Relationships, and Young Women’s Contraceptive Behavior

Non-heterosexual young women have a higher rate of unintended pregnancy than their heterosexual peers, but their fertility behaviors are understudied. We use longitudinal data from the Relationship Dynamics and Social Life study to investigate mechanisms contributing to non-heterosexual women’s higher pregnancy risk. These data include weekly reports of relationships, sex, and contraceptive use over 30 months. We compare the relationships and fertility behaviors of three groups: exclusively heterosexual (consistent heterosexual behavior, identity, and attraction); mostly heterosexual (heterosexual identity with same-sex behavior and/or same-sex attraction); and LGBTQ (any non-heterosexual identity). We find that mostly heterosexual and LGBTQ women behave differently from exclusively heterosexual women in ways likely to elevate their risk of unintended pregnancy: more distinct partners during the study period, more sexual intercourse with men, less frequent contraceptive use, less use of a dual method (condom plus hormonal method), and more gaps in contraceptive coverage. Mostly heterosexual women resemble LGBTQ women in their contraceptive behavior but have significantly more intercourse with men, which may increase their pregnancy risk relative to both LGBTQ and exclusively heterosexual women. We conclude by considering implications for LGBTQ health and the measurement of sexual minority populations.     

Incorporating heterogeneous intercourse records into time to pregnancy models

Information on the timing of intercourse relative to ovulation can be incorporated into time to pregnancy models to improve the power to detect covariate effects, to estimate the day-specific conception probabilities, and to distinguish between biological and behavioral effects on fecundability, and therefore the probability of conception in a menstrual cycle. In this paper, Bayesian methods are proposed for joint modeling of intercourse behavior and biologic fecundability. The model accommodates a sterile subpopulation of couples, general covariate effects, and heterogeneity among fecund couples in menstrual cycle viability and in frequency of unprotected intercourse. Methods are described for incorporating cycles with varying amounts of intercourse information into a single analysis. A Markov chain Monte Carlo algorithm is outlined for estimation of the posterior distributions of the unknowns. Themethods are applied to data from a North Carolina study of couples attempting pregnancy.     

Midlife Women Online: Evaluation of an Internet-Based Program to Prevent Unintended Pregnancy & STIs

Background: Midlife women are an underserved population in the areas of unintended pregnancy and STI prevention yet remain at risk for both health conditions. Methods: A randomized controlled trial of an Internet-based multimedia program to reduce risk of unintended pregnancy and STIs among midlife women was conducted with 164 women ages 40–55 years of age. Results: Women in the treatment condition compared to the control condition reported significant gains in attitudes, self-efficacy, and behavioral intentions at posttest. Conclusion: Interventions specifically targeted to midlife women can impact constructs known to reduce risk. Implications for future research and intervention development are presented.     

Do perceptions of their partners’ childbearing desires affect young women’s pregnancy risk? Further study of ambivalence

We explore whether young women’s perceptions of their sexual partners’ childbearing desires contribute to their risk of pregnancy. We used weekly journal data collected from 787 young women to measure their childbearing desires and their perceptions of their partners’ childbearing desires. We then conducted hazard modelling to predict pregnancy risk with variables based on interactions between the women’s desires and their perceived partners’ desires. Models that include perceived partners’ desires perform better than one based on women’s desires alone. The best model contains three significant predictors: one confirms the importance of pronatal, ambivalent, and indifferent desires for pregnancy risk; one indicates that the perceived partners’ antinatal desires reduce women’s pregnancy risk; and one suggests that women who both perceive their partners accurately and are in agreement with them have a lower pregnancy risk. The results indicate that perceived partner data can improve prediction and enhance our understanding of pregnancy risk.     

Modeling Seasonality in Fecundability,Conceptions, and Births

This paper develops a model of seasonal fluctuations in fecundability, conceptions, and births. We begin with a model of individual fecundability that combines behavioral and biological components, with particular attention to the roles of coital frequency, sperm concentration, fetal loss, and contraception. The individual-level model is then expanded into a model of seasonal fluctuations in births at the population level, which accounts explicitly for seasonal fluctuations in the size of the susceptible population. We illustrate the use of the model by analyzing proposed explanations of birth seasonality that rely on extreme summer heat.     

The contribution of HIV to fertility decline in rural Zimbabwe, 1985-2000

HIV-related sub-fertility has been reported for those populations in sub-Saharan Africa in which contraceptive use is low. We use data from a retrospective survey in rural Zimbabwe and multivariate logistic regression models to show that recent birth rates and current pregnancy rates are also lower among HIV-positive women than among HIV-negative women in those African populations where contraceptive use is high. The fertility reduction is smaller than where contraceptive use is low because age at first sexual intercourse is later and birth rates at older ages are already low. Nevertheless, total fertility is approximately 8.5 per cent lower and HIV-associated sub-fertility may account for as much as one-quarter of fertility decline in Zimbabwe since the late 1980s. Mechanisms for HIV-associated sub-fertility in rural Zimbabwe include more frequent widowhood and divorce, reduced coital frequency, increased amenorrhoea, and possibly, pelvic inflammatory disease. Miscarriage appears to be a less important factor than elsewhere possibly because syphilis is rare.     

Forced Displacement,Migration, and Fertility in Burundi

The civil war in Burundi (1993–2005) led to the forced displacement of a large part of the population. This study aims to explore how that displacement affected fertility behavior. Using a nationally representative, retrospective survey on birth and residential histories of 4,523 Burundian women, we examine the impact of conflict-induced displacement on fertility. These unique data enable us to distinguish between remaining-in-place, voluntary migration, and forced displacement, as well as to distinguish between periods spent “on the move” versus periods spent in residence in the new site. Adopting a semiparametric regression model, we analyze both the probability of the first pregnancy and the subsequent spacing of higher order pregnancies. We find that the risk of a first pregnancy was higher in the year in which a woman was forcibly displaced and lower in the year a woman migrated voluntarily. Residency in a new site increased the risk of pregnancy for both.     

Seasonality of coitus and seasonality of birth

Seasonal variation of birth rates has been observed in every population in which it has been studied. Many hypotheses have been advanced to account for the variation, including seasonal variation in frequency of coitus. This relationship is known to be true for other primates, but seasonal variation in coital rate has not been previously documented in man.This paper presents over one hundred woman-years of data on coital rates from about .fifty white, mostly well-educated, premenopausal, married, husband-present volunteers. Seasonal fluctuations were seen in coital rates, of about the same magnitude as seasonal variations in the white birth rates reported for New York City, 1962-64; for the United States, 1963; and for the highest socioeconomic quintile census tracts, Baltimore, 1952-56. However, shifting the birth rates back forty weeks to approximate conception dates revealed no association with the observed coital rates.If the pattern presented has great generality, seasonal variations in births cannot be explained by seasonality of coitus.     

Fecundability and coital frequency

Abstract The analysis previouslyreported (Population Studies, 23, 1969) of the risk of conceptionon different days of the menstrual cycleis extended so as to take someaccount of the agesof wives. The risks are estimated from data (basal body temperatures and occurrences of coitus) recorded by 241 married couples not using any contraceptives, to whom at least one child had previously been born. A mathematical formula relating natural fecundability to coital frequency is proposed and considered.     

New zodiacal influences on chinese family formation: Taiwan, 1976

Although Chinese folklore holds that the Dragon Year is an auspicious time to have a birth, notable increases in Chinese fertility in Dragon Years did not occur before 1976. Demographic explanations for the belated occurrence of this phenomenon rely on the notion of natural fertility: that is, couples’ lack of modem contraception had kept such decisions outside the realm of choice. The decomposition performed in this article, however, shows that the bulk of the 1976 Dragon Year baby boom on Taiwan was due to strategies that had always been available: marriage timing, abortion, and coital behavior. The natural fertility paradigm thus is insufficient in explaining the motivation for this behavior and should be complemented by institutional approaches.     

Racial differences in contraceptive choice: Complexity and implications

Previous research has failed to generate consensus about why black fertility has persistently exceeded that of whites in the United States. In an effort to shed light on this question, this article examines black/white differences in sociodemographic factors affecting contraceptive choice. Using data from the 1976 and 1982 National Surveys of Family Growth, we find a complex pattern of black/white differences. Not only does contraceptive choice vary by race, but the effects of such variables as age, marital status, and education also differ between blacks and whites. For example, compared with whites, black married women avoid coital methods, and compared with blacks, white women shift contraceptive behavior more as they change marital status. The complex nature of the racial differences in contraceptive choice are interpreted as reflecting differences in marriage patterns and trends.     

Conceptions of pregnancy health and motivations for healthful behavior change among women in American Samoa

Background

American Samoan women are particularly at risk of obesity-related non-communicable disease (NCD), requiring efficacious interventions to protect their health and that of their infants. Prior studies have identified pregnancy as an ideal time for behavior change interventions related to NCD.

A study of environmental and behavioral factors affecting pregnancy outcome in an Italian community

This study sought to identify environmental factors (socioeconomic conditions, work conditions, service availability, and so on) and behavioral factors (preventive health behaviors, pre- and postnatal care, and so on) which might be related to pregnancy outcome (childbirth, still birth, infant death, abortion). For this purpose high risk families (all families where an infant death or still birth had occurred in the last five years, a total of 253 cases) were compared with a random sample of the families where a normal child was born and survived during the same period (a sample of 239 cases). The results contain data on: (a) socioeconomic and demographic characteristics of study and control cases (residence, housing conditions, marital status or parents, work activity, and educational level): (b) the health status of the mother, prior and during pregnancy; (c) preventive health behavior such as prenatal care, nutrition, and use of drugs, tobacco, and alcohol; (d) working condition of the mother during pregnancy, type of work, work-related environmental risks, leave from work, and transportation; and (e) postnatal care and breast feeding patterns. The findings are discussed in terms of the present and future educational and service needs of the population.This study was made possible by the financial assistance of the World Health Organization, Division of Family Health. Dr. Figa-Talamanca is affiliated with the Institute of General Physiology, University of Rome, 00100 Rome, Italy.     

A Model of Age-specific Fecundability

A new model of the behavioural and physiological causes of age-specific variation in marital fecundability is presented. Total fecundability is decomposed into a series of susceptibility factors (the length of ovarian cycles, the length of the fertile period within each cycle, the probability that a cycle is ovulatory, and the likelihood that an act of unprotected intercourse within the fertile period results in conception) and an exposure factor reflecting the effect of duration of marriage on coital frequency. The impact of intra-uterine mortality on effective fecundability is also modelled. Data on western women, from which standard age curves of fecundability are estimated, suggest that any decline in fecundity between ages 30 and 40 is attributable to changes, not in the ability to conceive, but in the capacity to carry a pregnancy to term. Sensitivity tests suggest that the most important potential sources of inter-population variation in fecundability are intra-uterine death and the incidence of anovulatory cycles.     

Facts and artifacts in the study of intra-uterine mortality: A reconsideration from pregnancy histories

Summary The analysis of intra-uterine mortality is made difficult by the interaction of many factors, some of them being pure artifacts resulting from the way in which the data are collected, or from the under-reporting of induced abortions. This paper deals with some 'real factors' of variation in the risk of spontaneous abortion (mother's age, pregnancy order, number of previous abortions), and with some of these 'artifacts' (inclusion of induced abortion, memory effect, differential continuation rates). Special attention is paid to the effect of heterogeneity of the risk of abortion. After a discussion of problems of observation, data from two different samples are analysed, first in a classic way: variation with age and pregnancy order, comparison between the rates of abortion for current and previous abortion. Next, detailed data on successive pregnancies are used to derive estimates of the distribution of risk between women. It is concluded that this distribution could and should be taken into account, and that its effects are different from those of age. The possibility of differential continuation rates by outcome of pregnancy is discussed briefly, in connection with previous points.     

Writing the names: Marriage style,living arrangements,and first birth interval in a Nepali society

Using data from a Nepali population, this analysis argues that marriage style and postmarital living arrangements affect coital frequency to produce variations in the timing of first birth after marriage. Event history analysis of the first birth interval for 149 women suggests that women’s autonomy in marriage decisions and marriage to cross-cousins accelerate the pace of entry into first birth. Extended-household residence with reduced natal kin contact, on the other hand, significantly lengthens the first birth interval. These findings are consistent with previous arguments in the literature while offering new evidence for the impact of extended-family residence on fertility.