7 resultados para Fertility

em Duke University


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After the 2012 London Summit on Family Planning, there have been major strides in advancing the family planning agenda for low and middle-income countries worldwide. Much of the existing infrastructure and funding for family planning access is in the form of supplying free contraceptives to countries. While the average yearly value of donations since 2000 was over 170 million dollars for contraceptives procured for developing countries, an ongoing debate in the empirical literature is whether increases in contraceptive access and supply drive declines in fertility (UNFPA 2014).

This dissertation explores the fertility and behavioral effects of an increase in contraceptive supply donated to Zambia. Zambia, a high-fertility developing country, receives over 80 percent of its contraceptives from multilateral donors and aid agencies. Most contraceptives are donated and provided to women for free at government clinics (DELIVER 2015). I chose Zambia as a case study to measure the relationship between contraceptive supply and fertility because of two donor-driven events that led to an increase in both the quantity and frequency of contraceptives starting in 2008 (UNFPA 2014). Donations increased because donors and the Zambian government started a systematic method of forecasting contraceptive need on December 2007, and the Mexico City Policy was lifted in January 2009.

In Chapter 1, I investigate whether a large change in quantity and frequency of donated contraceptives affected fertility, using available data on contraceptive donations to Zambia, and birth records from the 2007 and 2013 Demographic and Health Surveys. I use a difference-in-difference framework to estimate the fertility effects of a supply chain improvement program that started in 2011, and was designed to ensure more regularity of contraceptive supply. The increase in total contraceptive supply after the Mexico City Policy was rescinded is associated with a 12 percent reduction in fertility relative to the before period, after controlling for demographic characteristics and time controls. There is evidence that a supply chain improvement program led to significant fertility declines for regions that received the program after the Mexico City Policy was rescinded.

In Chapter 2, I explore the effects of the large increase in donated contraceptives on modern contraceptive uptake. According to the 2007 and 2013 Demographic and Health Surveys, there was a dramatic increase in current use of injectables, implants, and IUDs. Simultaneously, declines occurred in usage of condoms, lactational amenorrhea method (LAM), and traditional methods. In this chapter, I estimate the effect of the increase in donations on uptake, composition of contraceptive usage, and usage of methods based on distance to contraceptive access points. The results show the post-2007 period is associated with an increase in usage of injectables and the pill among women living further away from access points.

In Chapter 3, I explore attitudes towards the contraceptive supply system, and identify areas for improvement, based on qualitative interviews with 14 experts and 61 Zambian users and non-users of contraceptives. The interviews uncover systemic barriers that prevent women from consistently accessing methods, and individual barriers that exacerbate the deficiencies in supply chain procedures. I find that 39 out of 61 women interviewed, both users and non-users, had personal experiences with stock out. The qualitative results suggest that the increase in contraceptives brought to the country after 2007 may have not contributed to as large of a decline in fertility because of bottlenecks in the supply chain, and problems in maintaining stock levels at clinics. I end the chapter with a series of four recommendations for improvements in the supply chain going forward, in light of recent commitments by the Zambian government during the 2012 London Summit on Family Planning.

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This paper uses a difference in difference model to investigate the impact of a large scale and high mortality 2005 earthquake in Pakistan on women’s fertility decisions and children’s health outcomes. Using a nationally representative, cross sectional DHS data from 2006 and geographical data from USGS, this paper investigates how variation in earthquake intensity levels can differentially impact total fertility for women and the likelihood of children suffering from diseases such as diarrhea, Acute Respiratory Infections (ARI) and fever. The post-earthquake results demonstrate a statistically significant increase in total fertility for areas closer to the epicenter of the earthquake, within a 100km radius of the rupture surface and at higher altitudes. Similarly, for children who were in-utero at the time of the earthquake, the probability of having early symptoms of ARI or fever was much smaller in lower earthquake intensity zones compared to the highest intensity zone.

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In a stochastic environment, long-term fitness can be influenced by variation, covariation, and serial correlation in vital rates (survival and fertility). Yet no study of an animal population has parsed the contributions of these three aspects of variability to long-term fitness. We do so using a unique database that includes complete life-history information for wild-living individuals of seven primate species that have been the subjects of long-term (22-45 years) behavioral studies. Overall, the estimated levels of vital rate variation had only minor effects on long-term fitness, and the effects of vital rate covariation and serial correlation were even weaker. To explore why, we compared estimated variances of adult survival in primates with values for other vertebrates in the literature and found that adult survival is significantly less variable in primates than it is in the other vertebrates. Finally, we tested the prediction that adult survival, because it more strongly influences fitness in a constant environment, will be less variable than newborn survival, and we found only mixed support for the prediction. Our results suggest that wild primates may be buffered against detrimental fitness effects of environmental stochasticity by their highly developed cognitive abilities, social networks, and broad, flexible diets.

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© 2013 The Association for the Study of Animal Behaviour.Social complexity, often estimated by group size, is seen as driving the complexity of vocal signals, but its relation to olfactory signals, which arguably arose to function in nonsocial realms, remains underappreciated. That olfactory signals also may mediate within-group interaction, vary with social complexity and promote social cohesion underscores a potentially crucial link with sociality. To examine that link, we integrated chemical and behavioural analyses to ask whether olfactory signals facilitate reproductive coordination in a strepsirrhine primate, the Coquerel's sifaka, Propithecus coquereli. Belonging to a clade comprising primarily solitary, nocturnal species, the diurnal, group-living sifaka represents an interesting test case. Convergent with diurnal, group-living lemurids, sifakas expressed chemically rich scent signals, consistent with the social complexity hypothesis for communication. These signals minimally encoded the sex of the signaller and varied with female reproductive state. Likewise, sex and female fertility were reflected in within-group scent investigation, scent marking and overmarking. We further asked whether, within breeding pairs, the stability or quality of the pair's bond influences the composition of glandular signals and patterns of investigatory or scent-marking behaviour. Indeed, reproductively successful pairs tended to show greater similarity in their scent signals than did reproductively unsuccessful pairs, potentially through chemical convergence. Moreover, scent marking was temporally coordinated within breeding pairs and was influenced by past reproductive success. That olfactory signalling reflects social bondedness or reproductive history lends support to recent suggestions that the quality of relationships may be a more valuable proxy than group size for estimating social complexity. We suggest that olfactory signalling in sifakas is more complex than previously recognized and, as in other socially integrated species, can be a crucial mechanism for promoting group cohesion and maintaining social bonds. Thus, the evolution of sociality may well be reflected in the complexity of olfactory signalling.

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From primates to bees, social status regulates reproduction. In the cichlid fish Astatotilapia (Haplochromis) burtoni, subordinate males have reduced fertility and must become dominant to reproduce. This increase in sexual capacity is orchestrated by neurons in the preoptic area, which enlarge in response to dominance and increase expression of gonadotropin-releasing hormone 1 (GnRH1), a peptide critical for reproduction. Using a novel behavioral paradigm, we show for the first time that subordinate males can become dominant within minutes of an opportunity to do so, displaying dramatic changes in body coloration and behavior. We also found that social opportunity induced expression of the immediate-early gene egr-1 in the anterior preoptic area, peaking in regions with high densities of GnRH1 neurons, and not in brain regions that express the related peptides GnRH2 and GnRH3. This genomic response did not occur in stable subordinate or stable dominant males even though stable dominants, like ascending males, displayed dominance behaviors. Moreover, egr-1 in the optic tectum and the cerebellum was similarly induced in all experimental groups, showing that egr-1 induction in the anterior preoptic area of ascending males was specific to this brain region. Because egr-1 codes for a transcription factor important in neural plasticity, induction of egr-1 in the anterior preoptic area by social opportunity could be an early trigger in the molecular cascade that culminates in enhanced fertility and other long-term physiological changes associated with dominance.

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© 2015 Published by Elsevier B.V.Tree growth resources and the efficiency of resource-use for biomass production determine the productivity of forest ecosystems. In nutrient-limited forests, nitrogen (N)-fertilization increases foliage [N], which may increase photosynthetic rates, leaf area index (L), and thus light interception (IC). The product of such changes is a higher gross primary production and higher net primary production (NPP). However, fertilization may also alter carbohydrate partitioning from below- to aboveground, increasing aboveground NPP (ANPP). We analyzed effects of long-term N-fertilization on NPP, and that of long-term carbon storing organs (NPPS) in a Pinus sylvestris forest on sandy soil, a wide-ranging forest type in the boreal region. We based our analyses on a combination of destructive harvesting, consecutive mensuration, and optical measurements of canopy openness. After eight-year fertilization with a total of 70gNm-2, ANPP was 27±7% higher in the fertilized (F) relative to the reference (R) stand, but although L increased relative to its pre-fertilization values, IC was not greater than in R. On the seventh year after the treatment initiation, the increase of ANPP was matched by the decrease of belowground NPP (78 vs. 92gCm-2yr-1; ~17% of NPP) and, given the similarity of IC, suggests that the main effect of N-fertilization was changed carbon partitioning rather than increased canopy photosynthesis. Annual NPPS increased linearly with growing season temperature (T) in both treatments, with an upward shift of 70.2gCm-2yr-1 by fertilization, which also caused greater amount of unexplained variation (r2=0.53 in R, 0.21 in F). Residuals of the NPPS-T relationship of F were related to growing season precipitation (P, r2=0.48), indicating that T constrains productivity at this site regardless of fertility, while P is important in determining productivity where N-limitation is alleviated. We estimated that, in a growing season average T (11.5±1.0°C; 33-year-mean), NPPS response to N-fertilization will be nullified with P 31mm less than the mean (325±85mm), and would double with P 109mm greater than the mean. These results suggest that inter-annual variation in climate, particularly in P, may help explaining the reported large variability in growth responses to fertilization of pine stands on sandy soils. Furthermore, forest management of long-rotation systems, such as those of boreal and northern temperate forests, must consider the efficiency of fertilization in terms of wood production in the context of changes in climate predicted for the region.