Fertility

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

Oncofertility and preservation of reproductive capacity in children and young adults

Abstract: With increasing numbers of survivors from cancer at a young age, the issue of fertility preservation has assumed greater importance. This review describes normal ovarian and testicular function and summarizes what is known about the effect of chemotherapy and radiotherapy on the gonads and uterus. All young patients with cancer or leukemia should have their fertility prognosis discussed before the initiation of treatment. Sperm and embryo cryopreservation should be considered standard practice and be widely available for those at significant risk of infertility. For prepubertal girls, ovarian tissue cryopreservation should be considered if the risk of premature menopause is high, but for the prepubertal boy there are no established techniques in current practice.

Sperm chromatin structure assay (SCSA): a tool in diagnosis and treatment of infertility

Abstract: Diagnosis of male infertility has mainly been based on the World Health Organization (WHO) manual-based semen parameter's concentration, motility and morphology. It has, however, become apparent that none of these parameters are reliable markers for evaluation of the fertility potential of a couple. A search for better markers has led to an increased focus on sperm chromatin integrity testing in fertility work-up and assisted reproductive techniques. During the last couple of decades, numerous sperm DNA integrity tests have been developed. These are claimed to be characterized by a lower intraindividual variation, less intralaboratory and interlaboratory variation and thus less subjective than the conventional sperm analysis. However, not all the sperm chromatin integrity tests have yet been shown to be of clinical value. So far, the test that has been found to have the most stable clinical threshold values in relation to fertility is the sperm chromatin structure assay (SCSA), a flow cytometric test that measures the susceptibility of sperm DNA to acid-induced DNA denaturation in situ. Sperm DNA fragmentation as measured by SCSA has shown to be an independent predictor of successful pregnancy in first pregnancy planners as well as in couples undergoing intrauterine insemination, and can be used as a tool in investigation, counseling and treatment of involuntary childlessness. More conflicting data exist regarding the role of sperm DNA fragmentation in relation to fertilization, pre-embryo development and pregnancy outcome in in vitro fertilization and intracytoplasmic sperm injection (ICSI).

Sustaining Fertility through Public Policy: The Range of Options

Abstract: This paper describes the range of policies that might be used to support fertility rates at a moderate level, that is, around an average of 1.7-1.9 births per woman. The paper argues that in selecting from the range of policy options, consideration must be given to the existing social-institutional framework in the particular country. In other words, there can be no single cross-national model for success. Each country must seek its own institutionally appropriate approach. Also, each country must deal with the realities of its own political economy. Strategies will not be accepted if they are not based upon a social consensus. In addition, as far as possible, policies to support fertility should be based upon a theory or theories as to why fertility has fallen to low levels in a particular setting. Given that fertility-support policies are likely to be expensive in one way or another, some understanding of the nature of low fertility will provide greater efficiency in policy implementation. The paper reviews several possible general theories relating to low fertility. Finally, it is argued that countries should have some notion about what it is that they are aiming to achieve. Inevitably, demographic sustainability (at least zero population growth) is an ultimate aim for all countries. The question is how far into the future is “ultimate”? Or expressed differently, how much of a decline in the size of the population or the labour force is the country willing to sustain before demographic sustainability is achieved? The example of Italy is used to illustrate this point.

Shifting Childrearing to Single Mothers: Results from 17 Western Countries

Abstract: THE FINAL THIRD of the twentieth century witnessed remarkable changes in patterns of family formation within most Western countries. During the two decades that followed World War II, marriage and childbearing occurred early in adulthood and were tightly linked. Then, beginning in the late 1960s in some countries and spreading to many others over the next few decades, the average age at first marriage increased as growing proportions of couples cohabited either as a prelude or an alternative to marriage (Bumpass and Sweet 1989b; Cherlin 1992; Casper and Cohen 2000; Kiernan 2000; Prinz 1995; Raley 2000; Smock 2000). Accompanying these changes in marriage practices were large increases in the prevalence of nonmarital childbearing (Sardon 2000; Ventura and Bachrach 2000), especially conspicuous in the face of rapid declines in marital fertility (Smith, Morgan, and KoropeckyjCox 1996). Labeled by van de Kaa (1987) as the “second demographic transition,” this multifaceted departure from the ordered sequence of marriage and childbearing has created challenges for researchers attempting to describe contemporary patterns of family formation with precision. The nonmarital fertility ratio (NMFR), perhaps the most closely watched indicator of changes in family structure, has become an increasingly blunt instrument in light of the share of nonmarital fertility accounted for by parental cohabitation. Moreover, most fertility studies cannot easily determine the number of children women have had by different partners (much less the number of childbearing partners that men have had). Different family forms are often confused in public rhetoric and sometimes even by those researchers who use marriage as a proxy for a nuclear household or nonmarriage as a proxy for single parenthood.

Effects of cross and self-fertilization on progeny fitness in lobelia cardinalis and l. siphilitica.

Abstract: Inbreeding depression, or the decreased fitness of progeny derived from self-fertilization as compared to outcrossing, is thought to be the most general factor affecting the evolution of self-fertilization in plants. Nevertheless, data on inbreeding depression in fitness characters are almost nonexistent for perennials observed in their natural environments. In this study I measured inbreeding depression in both survival and fertility in two sympatric, short-lived, perennial herbs: hummingbird-pollinated Lobelia cardinalis (two populations) and bumblebee-pollinated L. siphilitica (one population). Crosses were performed by hand in the field, and seedlings germinated in the greenhouse. Levels of inbreeding depression were determined for one year in the greenhouse and for two to three years for seedlings transplanted back to the natural environment. Fertility was measured as flower number, which is highly correlated with seed production under natural conditions in these populations. Inbreeding depression was assessed in three ways: 1) survival and fertility within the different age intervals; 2) cumulative survival from the seed stage through each age interval; and 3) net fertility, or the expected fertility of a seed at different ages. Net fertility is a comprehensive measure of fitness combining survival and flower number. In all three populations, selfing had nonsignificant effects on the number and size of seeds. Lobelia siphilitica and one population of L. cardinalis exhibited significant levels of inbreeding depression between seed maturation and germination, excluding the consideration of possible differences in dormancy or longterm viability in the soil. There was no inbreeding depression in subsequent survival in the greenhouse in any population. In the field, significant survival differences between selfed and outcrossed progeny occurred only in two years and in only one population of L. cardinalis. For both survival and fertility there was little evidence for the expected differences among families in inbreeding depression. Compared to survival, inbreeding depression in fertility (flower number) tended to be much higher. By first-year flower production, the combined effects on survival and flower number caused inbreeding depression in net fertility to reach 54%, 34% and 71% for L. siphilitica and the two populations of L. cardinalis. By the end of the second year of flowering in the field, inbreeding depression in net fertility was 53% for L. siphilitica and 54% for one population of L. cardinalis. For the other population of L. cardinalis, these values were 76% through the second year of flowering and 83% through the third year. Such high levels of inbreeding depression should strongly influence selection on those characters affecting self-fertilization rates in these two species.