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Fertility Control (fertility + control)
Selected AbstractsCross-strain protection reduces effectiveness of virally vectored fertility control: results from individual-based multistrain modelsJOURNAL OF APPLIED ECOLOGY, Issue 6 2007ANTHONY D. ARTHUR Summary 1Pest mammals have severe economic, environmental and social impacts throughout the world. Fertility control could reduce these impacts. Virally vectored immunocontraception (VVIC) has been proposed as an economic way to achieve this. However, the ability of an immunocontraceptive virus to control populations may be compromised if: (i) sufficient infected mice are not made infertile; (ii) the virus does not transmit at a sufficient rate; (iii) there is competition with field strains of virus; or (iv) its ability to induce infertility is altered by the presence of field strains. We tested this with stochastic, individual-based, disease,host models based on murine cytomegalovirus (MCMV) and house mice Mus musculus domesticus. 2Using field estimates of the MCMV transmission rate, immunocontraceptive MCMV (icMCMV) could prevent mouse populations from growing rapidly to damaging levels provided > 70% of mice infected with the virus became infertile. Successful control was possible even if engineering icMCMV reduced its transmission rate to c. 30% of the field-estimated value, but greater reductions in the transmission rate compromised successful control. 3Effective control was compromised if there was competition between icMCMV and field strains because of cross-immunity to infection or if previous infection with field strains blocked the development of infertility in mice subsequently infected with icMCMV. In these cases effectiveness was diminished, particularly if the transmission rate of icMCMV was reduced relative to field strains, or if close to 100% infertility of infected mice could not be achieved. If the blocking developed early after infection with field strains, doubling the transmission rate of icMCMV relative to field strains still could not produce successful control. 4Synthesis and applications. VVIC requires preliminary estimates of its efficacy to satisfy regulatory requirements before it can be released into the environment. Our models indicate that successful control of an outbreaking species using VVIC is possible if high levels of infertility can be achieved, but this is compromised by cross-strain protection and low transmission rates of engineered virus. Future research effort should focus on determining whether these compromising effects occur for specific engineered viruses and, if so, whether they can be overcome. [source] Towards a ZP-based contraceptive for marsupials: Comparative analysis and developmental expression of marsupial ZP genesMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 12 2007Carmen A. McCartney Abstract Fertility control in the form of a zona pellucida (ZP)-based immunocontraceptive has shown potential as a humane form of control for overabundant marsupials including the brushtail possum and macropods. Further refinement and development of a ZP-based vaccine requires detailed knowledge of the protein structure and expression in order to ensure maximum efficacy and specificity. Sequencing and comparative analysis of the ZP3 protein from three marsupial orders in this study found a high overall level of conservation; within order Diprotodontia, the ZP3 protein is 86.9,98.9% identical. ZP3 identity falls to 56.6,57.2%, when the grey, short-tailed opossum (a Didelphimorphian) is compared to dasyurid and diprotodontan marsupials. This is similar to its amino acid identity with ZP3 from eutherian species (50.7,52.8%). Comparison of a 21 amino acid epitope in marsupial ZP3 that has shown contraceptive effects, reveals 95,100% identity between the four macropodid species, 81,86% amino acid identity between brushtail possum and the macropods and 67,71% identity between the diprotodontans and the fat-tailed dunnart (a dasyurid). This is comparable to the level of identity between related eutherian mammals. The expression pattern of three ZP genes during brushtail possum and tammar wallaby pouch young development was examined by RT-PCR. This analysis of ZP gene expression has confirmed that ZP mRNA transcription begins in the ovary during pouch young development by about 51 days of age. The presence of ZP transcripts at this stage in pouch young development suggests that marsupial ZP gene transcription begins before the onset of follicular development. Mol. Reprod. Dev. 74: 1581,1589, 2007. © 2007 Wiley-Liss, Inc. [source] Fertility control: Oral versus self-administered vaginal misoprostol at home before surgical termination of pregnancy: a randomised controlled trialBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 1 2006Kevin Sunde Oppegaard Objective, To compare the impact of 400 ,g oral versus self-administered vaginal misoprostol at home on pre-operative cervical priming in both primigravid and multigravid women prior to first trimester surgical abortion. Design, Randomised controlled trial. Setting, Norwegian University Teaching Hospital. Sample, Three hundred and thirty-eight women undergoing surgical abortion between 7 and 12 weeks of gestation. Methods, The women were randomised to either 400 ,g of oral misoprostol the evening before or 400-,g of self-administered vaginal misoprostol at home the same day as vacuum aspiration. Main outcome measures, Pre-operative cervical dilatation, complications and acceptability. Results, The median cervical dilatation was 6.2 mm (range 0,11 mm) for the women in the 400 ,g oral misoprostol and 6.5 mm (range 0,11 mm) in the 400-,g vaginal misoprostol groups. The median pre-operative dilatation was larger in multigravidae (6.4 and 6.7 mm for the oral and vaginal routes, respectively) than in primigravidae (5.8 and 6.0 mm, respectively). In primigravidae, 19% achieved a pre-operative dilatation of ,7 mm, with no significant difference between oral and vaginal dosage. In multigravidae, 52% achieved a pre-operative dilatation of ,7 mm with vaginal dosage, compared with 36% with oral dosage (P= 0.03). There was no difference between non-immigrant versus immigrant women in pre-operative cervical dilatation. The 400-,g oral dosage group had a higher risk of bleeding, compared with the group receiving 400-,g vaginal misoprostol [odds ratio (OR) = 10.4; confidence interval (CI) 5.2,20.8]. There was no difference between non-immigrant and immigrant women in acceptability of self-administered vaginal misoprostol; almost all women found this administration route acceptable. Complications were minor and were distributed equally between the two dosage groups. Conclusions, The vaginal route will result in a satisfactory dilatation in about half of multigravidae but is much less effective in primigravidae. The oral route does not lead to satisfactory dilatation in either group and is associated with a higher occurrence of pre-operative bleeding. Self-administered vaginal misoprostol at home is highly acceptable. [source] Cross-strain protection reduces effectiveness of virally vectored fertility control: results from individual-based multistrain modelsJOURNAL OF APPLIED ECOLOGY, Issue 6 2007ANTHONY D. ARTHUR Summary 1Pest mammals have severe economic, environmental and social impacts throughout the world. Fertility control could reduce these impacts. Virally vectored immunocontraception (VVIC) has been proposed as an economic way to achieve this. However, the ability of an immunocontraceptive virus to control populations may be compromised if: (i) sufficient infected mice are not made infertile; (ii) the virus does not transmit at a sufficient rate; (iii) there is competition with field strains of virus; or (iv) its ability to induce infertility is altered by the presence of field strains. We tested this with stochastic, individual-based, disease,host models based on murine cytomegalovirus (MCMV) and house mice Mus musculus domesticus. 2Using field estimates of the MCMV transmission rate, immunocontraceptive MCMV (icMCMV) could prevent mouse populations from growing rapidly to damaging levels provided > 70% of mice infected with the virus became infertile. Successful control was possible even if engineering icMCMV reduced its transmission rate to c. 30% of the field-estimated value, but greater reductions in the transmission rate compromised successful control. 3Effective control was compromised if there was competition between icMCMV and field strains because of cross-immunity to infection or if previous infection with field strains blocked the development of infertility in mice subsequently infected with icMCMV. In these cases effectiveness was diminished, particularly if the transmission rate of icMCMV was reduced relative to field strains, or if close to 100% infertility of infected mice could not be achieved. If the blocking developed early after infection with field strains, doubling the transmission rate of icMCMV relative to field strains still could not produce successful control. 4Synthesis and applications. VVIC requires preliminary estimates of its efficacy to satisfy regulatory requirements before it can be released into the environment. Our models indicate that successful control of an outbreaking species using VVIC is possible if high levels of infertility can be achieved, but this is compromised by cross-strain protection and low transmission rates of engineered virus. Future research effort should focus on determining whether these compromising effects occur for specific engineered viruses and, if so, whether they can be overcome. [source] The ecological challenge of immunocontraception: editor's introductionJOURNAL OF APPLIED ECOLOGY, Issue 6 2000N.D. Barlow Summary 1. ,The problems of vertebrate pests are greater now than ever before, with vertebrate control constrained by problems of humaneness, scale and environmental impact. However, immunocontraception involves a conceptually ideal solution. Although not intrinsically novel, its delivery in baits or by a self-spreading vector and its effectiveness in pest control, are now the focus of growing international interest. 2. ,Major ecological questions correspond to the two forms of delivery: baits and vectors. First, given an effective immunocontraceptive, inserted into a bait and eaten by a pest, would the resulting level of sterilization in the population effectively suppress densities? Secondly, given that the immunocontraceptive agent can be inserted into a microparasitic or macroparasitic infective vector, would the modified vector persist at sufficient prevalence in the host population, and hence suppress densities to the required extent? 3. ,The papers published in this Special Profile focus on behaviour following sterilization or they model the likely impact of viral-vectored immunocontraception. They highlight advantages and disadvantages of immunocontraception and some general, novel and specific issues. These include the possibility of behaviourally mediated population responses to fertility control; the possible advantages of a mixed baiting and vector strategy; the competitiveness of a modified vector; the appropriateness of immunocontraception for controlling invasive vertebrates on islands; and the need for a ,pay-off' methodology for assessing genetic modifications against alternatives. 4. ,The findings offer significant benefits for management and policy: they will inform decisions on whether to pursue immunocontraception as a control option, and they provide evidence about efficacy and risk in applications to release genetically modified vectors. 5. ,Although many of the problems in developing immunocontraception technology are biotechnological, questions about the effectiveness of immunocontraceptive pest control are ultimately in the domain of ecologists. [source] Use of intrauterine devices (IUDs) for contraception in the common chimpanzee (Pan troglodytes)JOURNAL OF MEDICAL PRIMATOLOGY, Issue 2 2000Kenneth G. Gould The common chimpanzee (Pan troglodytes) is a species phylogenetically very close to man. It was not many years ago that the captive population of chimpanzees (P. troglodytes) was considered at risk because of perceived problems with reproductive success. With the potential need for many individuals for research in a variety of areas, particularly in the areas of parasitic and viral infections, an NIH-funded program was established to promote the breeding of the species. That program, the ,National Chimpanzee Breeding and Research Program', was highly successful, so successful, in fact, that there is now a surplus of animals available for current research programs. This situation has prompted the use of intrauterine devices (IUDs) as a method of fertility control. Overall, this method is successful and associated with a failure (of pregnancy) rate similar to that reported in the human. Physical and logistic constraints, however, render the method less than ideal for situations where a pregnancy rate of zero is desired. [source] Women's fertility and mortality in late mid life: A comparison of three contemporary populationsAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2009Emily Grundy Evolutionary theory suggests a trade-off between reproduction and somatic maintenance implying a negative relationship between parity and longevity, at least in natural fertility populations. In populations in which fertility control is usual, there are also a number of mechanisms that may link reproductive careers and later mortality, but evidence of associations between women's fertility patterns and their later life health has been judged inconclusive due to varying controls for socio-economic characteristics and marital status. Here, we build on three recent studies that followed a common framework to investigate associations between women's parity and timing of first and last birth with mortality in late middle age in three contemporary developed counties, Norway, England and Wales, and the USA. Data were drawn from whole population registers (Norway); a large census-based record linkage study (England and Wales), and a nationally representative survey linked to death records (USA). Results show that teenage childbirth was associated with higher mortality risks in late middle age in all three countries. Risks of death were significantly raised among nulliparous women in Norway and England and Wales, and also raised (although not significantly so) for childless US women. However, although higher parity was associated with a slight mortality disadvantage in England and Wales and the USA, the reverse seemed the case in Norway. These finding suggest that in populations in which fertility control is usual, contextual factors influencing the relative costs and benefits of childbearing may influence associations between fertility histories and later mortality. Am. J. Hum. Biol., 2009. © 2009 Wiley-Liss, Inc. [source] An Imperfect Contraceptive Society: Fertility and Contraception in ItalyPOPULATION AND DEVELOPMENT REVIEW, Issue 3 2009Alessandra Gribaldo Italy represents an unexpected and in some ways paradoxical outcome in terms of fertility control: a drop to one of the lowest birth rates in the world has been accompanied by continuing extensive use of traditional methods despite the availability of modern contraception. Using data from 349 interviews conducted in 2005,06 in four Italian cities, we argue that Italian women commonly achieve "unplanned" and desired conceptions through the use of withdrawal and natural methods. While data from other countries reveal similar notions of ambivalence surrounding pregnancy intentions and contraceptive use, Italy stands out for the surprising correlation between highly "managing" the conditions under which children are born and the socially commended approach of "letting births happen." Such results suggest the need to rethink theoretical understandings of low fertility. Through the use of non-technological methods, individuals manipulate culturally produced norms and beliefs about the appropriate time to have a child; simultaneously, their actions are embedded in larger cultural, economic, and political processes. [source] Sex, Breastfeeding, and Marital Fertility in Pretransition ChinaPOPULATION AND DEVELOPMENT REVIEW, Issue 2 2007William Lavely Coital frequency is at the heart of the debate over low marital fertility in pretransition China. This study argues that coital frequency in contemporary China is indicative of sexual behavior in an earlier era. Frequency of intercourse is low in China relative to Europe, a natural outgrowth of a traditional family system and related sexual culture only partially transformed by a century of family revolution. Customary sexual behaviors and breastfeeding practices together shaped the Chinese historical fertility regime as they did the European. As explanations for China's low marital fertility, these proximate determinants leave little scope for the operation of fecundity-reducing malnutrition on the one hand, or deliberate fertility control on the other. The fertility regimes of other pretransition agrarian societies more closely resemble China's than Europe's, seeming to confirm a pattern of European demographic exceptionalism. [source] | |||||||||||||