Fertility

About: Fertility is a research topic. Over the lifetime, 29988 publications have been published within this topic receiving 681106 citations.

Fertility, Female Labor Force Participation, and the Demographic Dividend

Abstract: We estimate the effect of fertility on female labor force participation in a cross-country panel data set using abortion legislation as an instrument for fertility. We find a large negative effect of the fertility rate on female labor force participation. The direct effect is concentrated among those aged 20-39, but we find that cohort participation is persistent over time giving an effect among older women. We present a simulation model of the effect of fertility reduction on income per capita, taking into account these changes in female labor force participation as well as population numbers and age structure.

Preservation of Fertility in Patients with Cancer

Abstract: The increasing number of young survivors of cancer who have favorable outcomes necessitates planning for the preservation of fertility, which may mean modifying the strategy for oncologic treatment. In addition to in vitro fertilization in women and sperm banking in men, new methods on the horizon include in vitro follicle maturation and techniques for tissue transplantation.

Religion as a Determinant of Marital Stability

Abstract: This paper develops hypotheses about the effects of husbands’ and wives’ religious affiliations on fertility. The hypotheses are based on two central ideas. First, religions differ in their fertility norms and corresponding tradeoffs between the quality and quantity of children; differences in religious beliefs between husband and wife may thus lead to conflict regarding fertility decisions and possible resolution through bargaining. Second, a low level of religious compatibility between the spouses may raise the expected probability of marital dissolution and thereby decrease the optimal amount of investments in spouse-specific human capital. Analyses of data from the 1987—1988 National Survey of Families and Households conducted in the United States suggest that both of these effects play important roles in explaining the observed linkages between the religious composition of unions and fertility behavior.

Changes with age in the level and duration of fertility in the menstrual cycle

Abstract: BACKGROUND: Most analyses of age-related changes in fertility cannot separate effects due to reduced frequency of sexual intercourse from effects directly related to ageing. Information on intercourse collected daily through each menstrual cycle provides the data for estimating day-specific probabilities of pregnancy for specific days relative to ovulation, and these estimates allow unconfounded analysis of ageing effects. METHODS: A total of 782 healthy couples using natural family planning methods contributed prospective data on 5860 menstrual cycles. Day of ovulation was based on basal body temperature measurements. Estimates of day-specific probabilities of pregnancy and the length of the fertile window were compared across age groups. RESULTS: Nearly all pregnancies occurred within a 6 day fertile window. There was no evidence for a shorter fertile window in older men or women. On average, the day-specific probabilities of pregnancy declined with age for women from the late 20s onward, with probabilities of pregnancy twice as high for women aged 19–26 years compared with women aged 35–39 years. Controlling for age of the woman, fertility was significantly reduced for men aged >35 years. CONCLUSIONS: Women’s fertility begins to decline in the late 20s with substantial decreases by the late 30s. Fertility for men is less affected by age, but shows significant decline by the late 30s.

The evolution of male and female parental care in fishes

Abstract: In this paper we propose an explanation for (a) the predominance of male care in fishes, and (b) the phylogenies and transitions that occur among care states. We also provide a general evolutionary model for studying the conditions under which parental care evolves. Our conclusions are as follows: (i) Parental care has only one benefit, the increased survivorship of young. It may, however, have three costs: a “mating cost,” an “adult survivorship cost,” and a “future fertility cost.” (ii) On average, males and females will derive the same benefit from care. They probably also pay the same adult survivorship cost. However, their mating cost and future fertility costs may differ, (iii) A mating cost usually applies only to males. However, this cost may be reduced by male territoriality and, in some situations, be entirely removed. Under this condition, natural selection on present reproductive success is equivalent for males and females, (iv) When fecundity accelerates with body size in females, while male mating success follows a linear relationship with body size, future fertility costs of parental care are greater for females than males. Although further tests are needed, a preliminary analysis suggests this often may be the case in fishes. Thus, the predominance of male parental care in fishes is not explained by males deriving greater benefits from care, but by males paying smaller future costs. Males thus accrue a greater net fitness advantage from parental care (see expressions [6] and [12]). (v) The evolution of biparental care from uniparental male care may occur because male care selects for larger egg sizes and increased embryo investment by females. This increases the benefit to the female of parental care, (vi) By contrast, uniparental female care may originate from biparental care when males are selected to desert. This occurs when female care creates a mating cost to males. In some cases male desertion may “lock” females into uniparental care. However, in many other cases females may be selected to desert, giving rise to “no care.” (vii) The origin of uniparental female care from no care is rare in externally fertilizing fishes. This is because the benefits of care rarely outweigh a female's future fertility costs (expression [9]). For internally fertilizing species, however, the benefit of care is high whereas the cost is probably low. Most of these species have evolved embryo retention, (viii) When parental care begins with male care and moves to biparental care, our analysis suggests that care evolution will include cyclical dynamics. Parental care in some fishes may thus be seen as transitional and changing through evolutionary time rather than as an evolutionarily stable state. In theory, “no care” may be a phylogenetically advanced state.