Average Birth Rate Research Articles

Global dynamics for two-species competition in patchy environment

An ODE system modeling the competition between two species in a two-patch environment is studied.Both species move between the patches with the same dispersal rate. It is shown that the species with largerbirth rates in both patches drives the other species to extinction, regardless of the dispersal rate. The more interesting case is when both species have the same average birth rate but each species has larger birth rate in one patch. It has previously been conjectured by Gourley and Kuang that the species that can concentrate its birth in a single patch wins if the diffusion rate is large enough, and two species will coexist if the diffusion rate is small. We solve these two conjectures by applying the monotone dynamics theory, incorporated with a complete characterization of the positive equilibrium and a thorough analysis on the stability of the semi-trivial equilibria with respect to the dispersal rate. Our result on the winning strategy for sufficiently large dispersal rate might explain the group breeding behavior that is observed in some animals under certain ecological conditions.

The effect of complementary and alternative medicine on subfertile women with in vitro fertilization.

About 10–15% of couples have difficulty conceiving at some point in their reproductive lives and thus have to seek specialist fertility care. One of the most commonly used treatment options is in vitro fertilization (IVF) and its related expansions. Despite many recent technological advances, the average IVF live birth rate per single initiated cycle is still only 30%. Consequently, there is a need to find new therapies to promote the efficiency of the procedure. Many patients have turned to complementary and alternative medical (CAM) treatments as an adjuvant therapy to improve their chances of success when they undergo IVF treatment. At present, several CAM methods have been used in infertile couples with IVF, which has achieved obvious effects. However, biologically plausible mechanisms of the action of CAM for IVF have not been systematically reviewed. This review briefly summarizes the current progress of the impact of CAM on the outcomes of IVF and introduces the mechanisms.

Of mice and (wo)men: factors influencing successful implantation including endocannabinoids

BACKGROUND One in six couples suffer from infertility problems requiring in vitro fertilization therapy; however, the average birth rates in the past decade per IVF-embryo transfer cycle have remained static at around 25%. Although implantation failure is considered a major cause of infertility in otherwise healthy women, inadequate uterine receptivity is considered to be responsible for only two-thirds of implantation failures and problems with the embryo itself are responsible for the other third, such that only 30% of oocytes that are contacted by sperm result in successful human term pregnancies. Due to technical and ethical considerations, most research into the factors affecting the success of embryo implantation has been performed in mice, but this may be less than ideal. METHODS Selected relevant literature detailing the similarities and differences between rodent and human reproductive physiology surrounding implantation were nominated for inclusion. Primary papers and review articles (and primary sources within these), published between 1975 and 2012, with a clear indication for a particular ligand or cell being involved in the implantation process or placentation in the mouse or woman, were thoroughly examined and used to construct the review. RESULTS Mice have been identified as suitable models for investigating the processes of early pregnancy in women, for many reasons including their predictable, relatively short gestation and the ability to deliberately breed mice with the absence of a desired gene. There is, however, increasing evidence to suggest that the reproductive systems of humans and mice differ considerably when considering early pregnancy events. CONCLUSIONS In this review, we examine what is already known about the normal implantation process and the intrinsic factors that affect implantation, and then compare the differences between mice models and women in the context of early pregnancy. We highlight numerous differences between the mice and women and conclude it is becoming clear that all of the data from mouse studies cannot be confidently extrapolated to human reproduction.

Mathematical analysis of an age-structured model for malaria transmission dynamics

A new deterministic model for assessing the role of age-structure on the transmission dynamics of malaria in a community is designed. Rigorous qualitative analysis of the model reveals that it undergoes the phenomenon of backward bifurcation, where the stable disease-free equilibrium of the model co-exists with a stable endemic equilibrium when the associated reproduction number (denoted by R0) is less than unity. It is shown that the backward bifurcation phenomenon is caused by the malaria-induced mortality in humans. A special case of the model is shown to have a unique endemic equilibrium whenever the associated reproduction threshold exceeds unity. Further analyses reveal that adding age-structure to a basic model for malaria transmission in a community does not alter the qualitative dynamics of the basic model, with respect to the existence and asymptotic stability of the associated equilibria and the backward bifurcation property of the model. Numerical simulations of the model show that the cumulative number of new cases of infection and malaria-induced mortality increase with increasing average lifespan and birth rate of mosquitoes.

A determination of the space density and birth rate of hydrogen-line (DA) white dwarfs in the Galactic plane, based on the UVEX survey

We present a determination of the average space density and birth rate of hydrogen-line (DA) white dwarfs within a radius of 1 kpc around the Sun, based on an observational sample of 360 candidate white dwarfs with g<19.5 and (g-r)<0.4, selected from the UV-excess Survey of the Northern Galactic Plane (UVEX), in combination with a theoretical white dwarf population that has been constructed to simulate the observations, including the effects of reddening and observational selection effects. The main uncertainty in the derivation of the white dwarf space density and current birth rate lies in the absolute photometric calibration and the photometric scatter of the observational data, which influences the classification method on colours, the completeness and the pollution. Corrections for these effects are applied. We derive an average space density of hydrogen-line (DA) white dwarfs with T_eff > 10,000K (M_V<12.2) of (3.8 +/- 1.1) x 1e-4 pc^-3, and an average DA white dwarf birth rate over the last 7e7 years of (5.4 + 1.5) x 1e-13 pc^-3 yr^-1. Additionally, we show that many estimates of the white dwarf space density from different studies are consistent with each other, and with our determination here.

Effect of N-ethyl-N-nitrosourea on the fatality, recovery of fertile period and breeding record in C57BL/6J mice

N-ethyl-N-nitrosourea (ENU) is a potent mutagen in a mouse model by inducing point mutation in a random manner and, in particular, causing heritable base substitutions in spermatogonia. In this study, systematic development of phenotype-driven mutant mice with large scale was carried out by using ENU. Nine-week-old male mice of C57BL/6J received intraperitoneal injection at three times with 100 mg/kg of ENU at weekly intervals for three weeks. After injections with ENU, the changes of body weight, fatality, recovery of fertile period, and breeding record were measured in these mice. Body weight lost as a result of ENU treatments was reversed after the last ENU injection. Live fertile male mice recovered from infertility from 104 to 165 days after ENU treatments were mated with C57BL/6J female mice for generation of G1 offspring. An average birth rate was 5.9 mice from 1 pair of paternal and maternal mice. All of 231 G1 offspring mice were analyzed by modified-SHIRPA with standard procedure at nine weeks of age. Among G1 mice, 166 mice were identified as mutagenic phenotypes in 20 test items. The changes in mutagenic phenotypes after ENU treatments, for instance, pattern in the region with a different color, touch escape, changes in head morphology, pupil, and teeth, and negative geotaxis etc., were found in these mice. Taken together, these results indicate that ENU may be a trans-generational mutagen in C57BL/6J mice.

The Float Nurse: Promoting Safety and Support at Delivery and Beyond

Poster Presentation Purpose for the Program Perinatal units are challenged with providing the nurse‐to‐patient ratios recommended by the Association of Women's Health, Obstetric and Neonatal Nurses (AWHONN). For uncomplicated births, one nurse should be assigned to the mother and another to the newborn. Healthy mothers and infants belong together, and separating them can disrupt early mother and infant interactions and affect breastfeeding. Our goals to align with Healthy People 2020 and the Baby Friendly Hospital Initiative's Ten Steps to Successful Breastfeeding motivated us to develop a program that would allow us to meet these goals. Proposed Change To promote early skin‐to‐skin contact between mother and newborn, eliminate or reduce separation of mothers from healthy stable infants, and promote early initiation of breastfeeding, we proposed to pilot a role for select nurses in our department called the float nurse. The float nurse acts as an advocate and liaison between the family, labor and delivery staff, mother–baby staff, and healthcare providers. The float nurse is present at uncomplicated vaginal deliveries and meets the AWHONN standard of being the nurse assigned to the newborn. She provides initial breastfeeding and newborn education as well as performs the initial physical assessment. The float nurse transitions the mother and infant together from the labor and delivery unit to the mother–baby unit. Implementation, Outcomes, and Evaluation A departmental task force consisting of leadership, clinical specialists, healthcare providers, and nurses met to develop the float nurse pilot. They obtained a baseline survey of current patient satisfaction, breastfeeding initiation rates, and quality of breastfeeding assistance. The department task force then determined the skill set required and identified potential float nurse participants. The 2‐week pilot enlisted six registered nurses with 24‐hour nurse coverage. The float nurse carried a cell phone and was contacted by the labor and delivery nurse when a birth was imminent. Despite a much higher than average birth rate during the pilot period, participating nurses were able to survey each participating mother. Preliminary survey results showed improved patient satisfaction, breastfeeding initiation rates, and quality of breastfeeding assistance. We proposed that positions be budgeted for FY 2013 to continue with this model of care. Implications for Nursing Practice This model of practice has the advantage of meeting the AWHONN staffing recommendation as well as promoting early nursing interventions that promote maternal–infant attachment and breastfeeding success. It also has the potential to provide other avenues of practice for the obstetric and neonatal nurse.

Increase in caesarean deliveries after the Australian Private Health Insurance Incentive policy reforms.

BackgroundThe Australian Private Health Insurance Incentive (PHII) policy reforms implemented in 1997–2000 increased PHI membership in Australia by 50%. Given the higher rate of obstetric interventions in privately insured patients, the reforms may have led to an increase in surgical deliveries and deliveries with longer hospital stays. We aimed to investigate the effect of the PHII policy introduction on birth characteristics in Western Australia (WA).Methods and FindingsAll 230,276 birth admissions from January 1995 to March 2004 were identified from administrative birth and hospital data-systems held by the WA Department of Health. Average quarterly birth rates after the PHII introduction were estimated and compared with expected rates had the reforms not occurred. Rate and percentage differences (including 95% confidence intervals) were estimated separately for public and private patients, by mode of delivery, and by length of stay in hospital following birth. The PHII policy introduction was associated with a 20% (−21.4 to −19.3) decrease in public birth rates, a 51% (45.1 to 56.4) increase in private birth rates, a 5% (−5.3 to −5.1) and 8% (−8.9 to −7.9) decrease in unassisted and assisted vaginal deliveries respectively, a 5% (−5.3 to −5.1) increase in caesarean sections with labour and 10% (8.0 to 11.7) increase in caesarean sections without labour. Similarly, birth rates where the infant stayed 0–3 days in hospital following birth decreased by 20% (−21.5 to −18.5), but rates of births with >3 days in hospital increased by 15% (12.2 to 17.1).ConclusionsFollowing the PHII policy implementation in Australia, births in privately insured patients, caesarean deliveries and births with longer infant hospital stays increased. The reforms may not have been beneficial for quality obstetric care in Australia or the burden of Australian hospitals.

Large-scale population-based genetic screening and prenatal diagnosis for thalassemias in Zhuhai City of Guangdong Province

To report the results of preventive control program of severe thalassemias in Zhuhai City of Guangdong Province from 1998 to 2010. As the guide centre of marriage and childbearing and the greatest maternity hospital in Zhuhai City of Guangdong Province, Zhuhai Municipal Maternity and Child Healthcare Hospital constructed the genetic screening network for thalassemias testing and referred for follow-up and for genetic counseling. The couples for premarital medical examination or regular healthcare examination in pregnancy were enrolled to this preventive control program. A conventional strategy of screening for heterozygote was used to identify the α- and β-thalassemia traits in women and their spouses according to the standard procedures of hematological phenotype analysis which was recommended by Thalassemia International Federation (TIF). Then those suspected couples at risk were diagnosed for α- and β-thalassemia by PCR-based DNA assays. The couples at risk for severe thalassemias were counseled and offered prenatal diagnosis and termination of pregnancy in case of an affected fetus in the rights of consent and of option voluntarily. From January 1998 to December 2010, 85 522 brides and grooms-to-be for premarital screening and 41 503 pregnant women in addition to 14 141 partners for prenatal screening were recorded, the covering rates of premarital screening and prenatal screening in the city were 92.698% (from 1998 to 2003) and 27.667% (from 2004 to 2010), respectively. Totally 10 726 cases were found to be the carriers of thalassemias, with 7393 for α-thalassemia (5.237%, 7 393/141 166) and 3333 for β-thalassemia (2.361%, 3 333/141 166). A total of 257 couples at-risk for severe thalassemias were detected including 190 for α-thalassemia and 67 for β-thalassemia. Among them, 251 (97.7%, 251/257) couples were performed prenatal diagnosis. During the preventive control program, a total of 72 fetuses with severe thalassemias including hemoglobin H disease were voluntarily terminated. In Zhuhai City, the average annual birth rate of fetuses with severe thalassemia was declined by 32.9% (49/149). This study has reduced effectively birth rate of perinatal infants with severe thalassemias in Zhuhai City by genetic screening and prenatal diagnosis of thalassemia in the large population of 13 years. Our summary comes out of technical proposals for prenatal screening and diagnosis, which could be take example by preventative control of thalassemia in other regions of China where are prevalent.

Establishing of a pay for performance program for in vitro fertilization (IVF)

To establish a pay for performance program with Iowa's largest insurer (Wellmark, 60% covered lives) that would reward good IVF outcomes. Retrospective analysis. We determined Wellmark's reimbursement for IVF, maternal, and neonatal care up to the day of discharge for live-birth deliveries for women who received their care at our center. Cost for all of our IVF patients were extrapolated from these data. We recalculated and compared estimated costs to Wellmark had our outcomes been equivalent to national averages by using 2006 CDC data for IVF pregnancy and multiple gestation rates. 38 insured women (31 singletons, 4 twins, and 3 triplets) who delivered at our center cost $42,893 for singletons, $209,716 for twins, and $268,274 for triplets. A total of 202 IVF live births: 164 (81%) singletons, 35 (17%) twins, and 4 (2%) triplets cost $15,404,715. If national average multiple birth rates (69%, 29%, and 2% respectively) were applied to our program volume then total healthcare costs would have been $19,408,467. Wellmark insures 50% of our IVF patients yielding a yearly savings of $2,001,876 due to our program's relatively low multiple birth rate. Wellmark recognized their savings and agreed to a two- tiered pay for performance program that pays an additional $5000 for every fresh IVF cycle start if live-birth rates remain 8% above and multiple gestation rates 8% below national CDC averages. Respective rates 4% above and 4 % below national averages results in a $1500 payment. The estimated $2 million savings is likely conservative since we did not take into account long-term health problems associated with multiple gestations. This model should encourage other IVF centers to establish pay for performance programs that recognize excellent outcomes.

Demography, Development and Control of the Coastal Space on the Pacific Coast of Mexico

During the four final decades of the last century, demographicgrowth in Mexico slowed significantly. This trend continued during the firstdecade of the 21st century, in tune with current expectations in the country.However, during precisely the same decades, the opposite phenomenon hasbeen occurring in the country’s coastal territories, i.e. demographic growthresulting not from an increase in average birth rates, which have followedmore or less the same trends as among the rest of the country’s inhabitants,but from immigration into these areas. This phenomenon is of itself reliableproof of the growth in investment of both public and private capitalin coastal territories. The only exception to this trend is provided by threecoastal municipalities in the state of Sinaloa, created in the early 1990s andtaken over, literally, by drug-trafficking activities. The vast majority of thesenew inhabitants of the Mexican coastlines are people who have arrivedfrom inland in search of jobs, in the hope of improving their lives. For thenew «costeños», life in these latitudes is completely different to that whichthey had experienced in their previous homes, whether in the plateau orthe central plain, the deserts of the north, the limestone country of the interiorof the Yucatán peninsula or the tortuous hillsides of the mountains:new rhythms and ways of working, different local eating habits and modesof dress, unknown climatic phenomena and their consequences for dailylife, strange idiomatic expressions, and finally the exotic affection of the native «costeños» for their countryside and their local flora and fauna. Toanalyse the case study, we propose the concept of the «coastal region». Weuse demographic information both at national level and from the coastalstates and municipalities, taken from national censuses of population andhousing done in the decades from 1950 to 2010, published by the InstitutoNacional de Estadísticas, Geografía e Informática (National Institute ofStatistics, Geography and it, inegi), as well as photographs from variousarchives and from the author’s collection. It is not appropriate to talk of an«experimental design» in this work, since it is not an «experiment» but anattempt to explain what has been happening among the inhabitants of theMexican coasts on the basis of the developing situation over some 50 yearsof constant colonisation.

Impact of vaccination and birth rate on the epidemiology of pertussis: a comparative study in 64 countries

Bordetella pertussis infection remains an important public health problem worldwide despite decades of routine vaccination. A key indicator of the impact of vaccination programmes is the inter-epidemic period, which is expected to increase with vaccine uptake if there is significant herd immunity. Based on empirical data from 64 countries across the five continents over the past 30-70 years, we document the observed relationship between the average inter-epidemic period, birth rate and vaccine coverage. We then use a mathematical model to explore the range of scenarios for duration of immunity and transmission resulting from repeat infections that are consistent with empirical evidence. Estimates of pertussis periodicity ranged between 2 and 4.6 years, with a strong association with susceptible recruitment rate, defined as birth rate × (1 - vaccine coverage). Periodicity increased by 1.27 years on average after the introduction of national vaccination programmes (95% CI: 1.13, 1.41 years), indicative of increased herd immunity. Mathematical models suggest that the observed patterns of pertussis periodicity are equally consistent with loss of immunity that is not as rapid as currently thought, or with negligible transmission generated by repeat infections. We conclude that both vaccine coverage and birth rate drive pertussis periodicity globally and that vaccination induces strong herd immunity effects. A better understanding of the role of repeat infections in pertussis transmission is critical to refine existing control strategies.

The Developing Nature of Menstrual and Reproductive Factors Associated with Breast Cancer Risk among Women in an Urban Region of China.

Abstract Introduction: The incidence rate of female breast cancer has increased rapidly over the past 20 years in China. It has become the leading cause of newly diagnosed cancer and a major cause of mortality among women in some large Chinese cities with higher socio-economic status. This was partly explained by the change of lifestyle and reproductive risk factors. However, little data exists on the extent to which the menstrual and reproductive factors with breast cancer risk have changed in other less developed Chinese cities.Method: One cross sectional study was conducted in urban region of Taiyuan of China from September 2008 to March 2009. One thousand and five hundreds healthy women were invited to complete a self-administered questionnaire. Participants' characteristics, including age, education, occupation, weight, height, age at menarche, age at first birth, parity, duration of breastfeeding, and age at menopause were collected and analyzed. Study subjects were divided into six groups: younger than or equal to 20, 21 to 30, 31 to 40, 41 to 50, 51 to 60 and older than 60 years old.Results: One thousand four hundreds and twenty eight women returned the questionnaire. The response rate was 95.2%. Median age of women in this study was 39 years old (range: 16 – 86 years old). There was a 4.8cm difference in the mean height between women born in 1990s and 1940s. The average age at menarche dropped from 16 years for women aged above 60 to 14.3 years for those younger than 20 years old. The average birth rate markedly decreased from 4.4 births per woman in the 1960s to 1.1 births per woman in the 1990s. The mean age at first birth increased 5.6 years through the period from the 1940s to 1980s. The breastfeeding time significantly reduced from 20.3 months to 3.6 months over 40 years.Conclusion: This study indicates that there has been significant change in the menstrual and reproductive factors associated with breast cancer risk in the last 40 years. These changes will certainly influence the incidence rate of breast cancer in the local city. Therefore, measures are needed to enhance the awareness of breast cancer and its early-detection methods among the urban region women in China. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6068.

Reproductive parameters of wild Trachypithecus leucocephalus: seasonality, infant mortality and interbirth interval

Understanding the reproductive parameters of endangered primate species is vital for evaluating the status of populations and developing adequate conservation measures. This study provides the first detailed analysis of the reproductive parameters of wild white-headed langurs (Trachypithecus leucocephalus), based on demographic data collected over an 8-year period in the Nongguan Karst Hills in Chongzuo County, Guangxi, China. From 1998 to 2002, a total of 133 live births were recorded in the population based on systematic censuses. Births occurred throughout the year, but the temporal pattern was highly correlated with seasonal variation in temperature and rainfall, with the birth peak coinciding with the dry and cold months of November-March. The average birthrate was 0.47+/-0.13 births per female per year and mortality for infants younger than 20 months was 15.8%. From 1998 to 2006, 14 females gave birth to 41 infants in four focal groups. The average age at first birth for female langurs was 5-6 years (n = 5) and the interbirth interval (IBI) was 23.2+/-5.2 months (median = 24.5 months, n = 27). Infants are weaned at 19-21 months of age. The IBI for females with infant loss before weaning was significantly shorter than those for females whose infants survived. It appears that birth seasonality in the white-headed langurs is influenced by seasonal changes in food availability. The timing of conceptions was found to coincide with peak food availability. The reproductive parameters for white-headed langurs reported here are quite similar to those reported for other colobine species. One major difference is our observation of lower infant mortality in Trachypithecus.

Some Reproductive Parameters of an Estuarine Population of Indo-Pacific Bottlenose Dolphins (&lt;I&gt;Tursiops aduncus&lt;/I&gt;)

The Port River estuary (Adelaide, South Australia) supports a population of Indo-Pacific bottlenose dolphins (Tursiops aduncus) despite its heavily modified habitat. This paper reports the calving season, birth rate, calf mortality, and inter-birth interval of the resident population, all factors important in the conservation of this population. Between 1989 and 2005, 1,176 boat surveys were undertaken, covering all seasons for each year. All dolphins encountered were photographed, and their location, number, age category, and behaviour were recorded. Dolphin identity was determined a posteriori using photo-identification. Results indicated a calving season from December to March, which coincided with the maximum surface water temperature of the estuary. Inter-birth intervals were consistent with the literature—3.8 y when the previous calf was weaned and 1.7 y when the previous calf died—with the exception of one special case. Forty-five calves were born to resident females between 1989 and 2005, and the average crude birth rate was 0.064, which is similar to that found for other bottlenose dolphin populations. First-year calf mortality (30%) and mortality rate for calves prior to weaning (46%) were higher than mortality rates described for other locations. Minimal predation is thought to occur in the estuary, and there was no evidence of poor condition in the mothers, suggesting that the high mortality rates were caused by direct impacts on calves such as entanglements, boat strikes, deliberate attacks, or exposure to toxic pollution.

Reproductive Strategies of Trachypithecus pileatus in Arunachal Pradesh, India

We studied reproductive behavior of free-ranging capped langurs (Trachypithecus pileatus) in the Pakhui Wildlife Sanctuary, Arunachal Pradesh, India. Four species of primates —Trachypithecus pileatus, Macaca mulatta, M. assamensis, and Nycticebus bengalensis— live there. We studied the mating seasons, mating frequency, copulatory attempts, time spent in copulation, and interval between 2 successive copulations, gestation length, and interbirth interval of 4 groups of capped langurs during 2001–2003. We observed 2 mating seasons in a year. The first was larger, comprising 5 months (September–January), and the second was short, April and May. Mating was intensive in the morning session (0600–1000 h); 57% of total mating events occurred then. The average gestation period was 200 d. November was the most favorable month for breeding. In a year, 107 mating events occurred involving 5 adult females. Average time per mounting attempt is 12 s. Duration of mounting was the maximum in November. Interbirth interval was 23 months and 10 d. The birth season was 129 days, December–April; 53% of births occurred in February and March. Average birth rate is 0.386 birth/female/yr.

The Effect of Medicaid Family Planning Expansions on Unplanned Births

Medicaid covers nearly 50% of all family planning services nationally. Between 1994 and 2001, 11 states implemented demonstration programs that expand coverage of family planning beyond the federally mandated minimum coverage levels. We estimate the effect of income- and postpartum-based eligibility expansions on birth rates using states that did not expand coverage as a control for states that did expand coverage. Our data span 1991-2001 and include all 50 states. We also estimate net expansion costs from societal and state perspectives for 5 expansions that published incremental expansion costs. We find that Medicaid eligibility expansions lowered average annual birth rates in all states. Birth rates were reduced on average by 1.95 points in income-based expansions and by 0.87 points in postpartum-based expansions. The cost offset of maternal and child health expenditures of the expansions exceed program costs in all states but California. This result is likely because the objectives and scope of the California program goes beyond just unplanned births, which makes the program cost higher relative to the reduction in births. Both income- and postpartum-based family planning expansions either yield financial benefits or, at the very least, are cost neutral from the perspective of state governments. Income-based expansions are significantly more effective because eligibility is not limited to only postpartum women. The experience of these early family planning expansions should be a guide for other states considering family planning benefit expansions. From the national perspective, 4 out of 5 programs were cost neutral, although California had significantly higher costs. From the state's perspective, all of the expansions were either budget neutral or yielded a net cost savings.

Season of Birth and Schizophrenia in Northeast Brazil

Although the association of schizophrenia and winter birth has been replicated many times in the Northern hemisphere, studies in the Southern hemisphere have been less consistent in their findings. A study from NE Brazil indicated the period between May and July, 3 months after the peak in rainfall, as a risk period for schizophrenia birth. We report findings from a random selection of charts (N = 1789) from the only public inpatient psychiatric facility in Ceará, Brazil (2 degrees to 5 degrees S). We compared the seasonality of birth in the schizophrenia group (N = 406) to multiple control groups: (1) psychosis not otherwise specified (N = 868), (2) other psychiatric diagnoses (N = 515), and (3) the average monthly birth rate in the general population. Patients with schizophrenia had a significantly greater risk of being born in the risk period compared with any of the control groups. There is a significant association between rainfall in a month and schizophrenia births 3 (p = 0.03) and 4 months (p = 0.01) later. This study corroborates findings of a significant seasonality in schizophrenia births in northeast Brazil.

P20.08: Power Doppler ultrasound assessment of follicular vascularization: prospective clinical interest evaluation for IVF management—preliminary results

Average live birth rate in Europe remains ∼28% per transfer despite advances in in-vitro fertilization (IVF). Factors such as maternal age, ovarian reserve, serum estradiol concentrations, follicular number and size are being investigated as possible prognostic factors of success. In regard to the oocyte quality at the time of retrieval, a relationship between follicular vascularization and the IVF outcome has been established. Conventional pulsatility indices of intra-ovarian arteries are very difficult to use routinely. The aim of this study was to investigate the accuracy of power Doppler ultrasonography for assessment of follicular vascularization during IVF attempts, as well as a prognostic factor of IVF outcome. 35 patients undergoing IVF treatment were prospectively recruited. Using power Doppler ultrasound, we assessed individual follicular vascularization of about three follicules in each ovary, by a subjective graduation, at the time of oocyte collection. Using a validated system, follicles were determined to be at high or low grade on regard with the extension of vascularization. Subsequent follicular and oocyte quality parameters were collected: mean follicular diameter, presence and maturity of the corresponding oocyte, quality of zygotes and cleaved embryos whether transferred or not. A total of 187 follicles were studied. The assessment of perifollicular vascularization, although highly subjective, was feasible in 92.51% of cases. Vascularization grade was not dependent on follicular size. There was no significant difference in any of the analysed follicular and oocyte quality parameters between high and low grade follicles. Power Doppler assessment of perifollicular vascularization does not seem to be a useful procedure to evaluate follicular and oocyte quality.

Effects of group size on birth rate, infant mortality and social interactions in Formosan macaques at Mt Longevity, Taiwan

In social animals, the influence of life-history traits on group structure and size is potentially important in the context of the evolution of social systems. Birth rate and infant survival have been differently predicted as a function of group size by models of the evolution of group living in primates. A wild population of the Formosan macaque, Macaca cyclopis that inhabits Mt Longevity, Taiwan has been monitored since July 1993 to collect demographic, reproductive and social behaviour data. Little is known about the effects of troop size on population growth in Formosan macaques. In this paper, we have presented for the first time 5-years of data (1997–2001) on the troop dynamics of 14 social troops. We also examined the effects of troop size on birth rate, infant mortality and inter-troop social interactions. The annual average troop size increment fluctuated from 1.94% to 10.97%. The annual average troop size of 14 groups was 43.57 ± 15.88 individuals in 1997, and increased to 55.97 ± 16.86 individuals in 2001. The per-capita rates of troop size increase was negatively correlated with troop size without infants (F1,12 = 5.57, P < 0.05). The average birth rate (birth per adult female) was 0.78 (± 0.07, n = 14) and it was not linearly related to troop size, nor the number of adult females (P > 0.33). The average infant mortality was 0.16 (± 0.09, n = 14), which was relatively constant regardless of the troop size category (small, medium or large). Intertroop dominance was closely dependent on the number of adult males and females rather than group size. Thus larger group size imposed an advantage on habitat utilization without the appearance of low birth rate or high infant mortality. On the other hand, infant mortality increased and infant survival per adult female decreased when the percentage of adult females increased in troops. Therefore, competition among adult females plays an important role partially supporting the predation — intra-group feeding competition hypothesis.