The causes of the decline in fecundability with age

Demographers have frequently suggested that a woman's fecundability reaches a maximum some time in her 20's and thereafter remains at a plateau for some years. Recent work by Bendel and Hua (1978) reinforces the author's previously expressed suspicion that this theory is incorrect. This work is an effort to synthesize current knowledge about the variation with age of the reproductive parameters underlying fecundability. It is suggested that: 1) the major cause of the decline in fecundability across ages 20-40 is a decline in coital rates, and 2) a smaller part of the decline in fecundability is caused by a rise in the risk of unrecognized spontaneous abortion. It is concluded that the biological capacity to conceive does not vary significantly between ages 20-40.     

Distributions of coital rates and of fecundability

Abstract

Attempts have been made to fit distributions of conception waits on the assumption that fecundability is distributed as a Pearson Type I beta distribution. Since the fits were unsatisfactory (Majumdar and Sheps, 1970), the question arises whether fecundability is distributed as a Type III. If it were, then the probability of coitus should also be distributed as a Type III, and distributions of coital rates should be better fitted by the negative binomial than by Skellam's distribution. The data available for such fits have been briefly reviewed here and fits attempted. There is some slight evidence in favor of the hypothesis, but more data are needed before the question can be decisively answered.     

Are there changes in postural regulation across the lifespan?

Abstract

The purpose was to obtain parameters of postural regulation (n?=?1724) of asymptomatic subjects (6–97 years). The maximum postural stability and capacity of postural subsystems were calculated for the age ranges from 34 to 35 years (men) and from 38 to 44 years (women). A significant decline in postural performance was observed in the 40s (men) and 50s (women). Data can be used in the evaluation of dizziness and balance disorders in people of all ages.     

The age pattern of fecundability: an analysis of French Canadian and Hutterite birth histories

This paper analyzes the age pattern of effective fecundability from populations with no evidence of deliberate fertility control using a new convolution model of fecundability. The analysis is based on a sample of Hutterite birth histories from the mid-20th century, and birth histories of French Canadians from the 17th and 18th centuries. The main findings are as follows: 1) the level of effective fecundability is higher among the French Canadians compared to the Hutterites; 2) effective fecundability peaks at age 20 for the Hutterites, and in the early to mid-20s for the French Canadians; 3) Hutterite effective fecundability declines almost linearly from age 20 to 45, and French Canadian effective fecundability declines slowly from its peak to the early 30s, and more rapidly at older ages; and 4) the duration of postpartum amenorrhea is longer for the French Canadians than for the Hutterites. Because of the shorter periods of postpartum amenorrhea the Hutterites have about the same average number of children as the French Canadians, even though the French Canadians have higher effective fecundability.     

Evidence of increasing natural fertility in Taiwan

Abstract

A comparison of the age‐specific marital fertility experience of three successive cohorts in Taiwan indicates that the later cohorts have experienced progressively higher rates of natural fertility at each age from 15–19 to 35–39. Their fecundability is correspondingly higher and post‐partum sterility, shorter. These changes in natural fertility levels occurred almost simultaneously with recorded changes in health and nutrition levels. These findings support the hypothesis that during the process of modernization and the fertility transition, the level of natural fertility increases, potentially as a result of improvements in health and nutrition, and changes in lactation practices. It is the net effect of increases in natural fertility on the one hand and deliberate fertility regulation on the other, that determines the course of fertility over time, especially at early stages of modernization and the fertility transition.     

Global variation in young adult central nervous system tumor incidence by region,age, and sex from 1988 to 2012

BackgroundCentral nervous system (CNS) tumors result in tremendous morbidity and mortality. Incidence of CNS tumors in young adults is less studied. It is unknown how young adult CNS tumor incidence has changed globally in recent decades.MethodsWe used Cancer Incidence in Five Continents (CI5) data (1988–2012) to estimate incidence rates (IR), average annual percent change in incidence (AAPC; 95% confidence intervals [95% CI]), and male-to-female incidence rate ratios (IRR; 95% CI) by six histologies and age at diagnosis (20–29years, 30–39years). Tumors were classified as astrocytic, medulloblastoma, ependymal, oligodendroglial, meninges, and other embryonal. Geographic regions were defined using the United Nations Statistics Division geoscheme.ResultsThere were 78,240 CNS tumor cases included. 20–29-year-old (yo) rates were lower than 30–39 yo in most regions for astrocytic, oligodendroglial and ependymal tumors. Globally, astrocytic tumor incidence decreased (20–29 yo AAPC: − 0.70; 95% CI: − 1.32, − 0.08) while incidence increased for oligodendroglial (20–29 yo AAPC: 3.03; 95% CI: 1.57–4.51; 30–39 yo AAPC: 2.67; 95% CI: 0.79–4.58), ependymal (20–29 yo AAPC: 1.16; 95% CI: 0.31–2.03; 30–39 yo AAPC: 2.29; 95% CI: 1.14–3.46), medulloblastoma (30–39 yo AAPC: 0.6; 95% CI: 0.04–1.24) and tumors of the meninges (20–29 yo AAPC: 1.55; 95% CI: 0.04–3.07). There was a 20–40% male incidence excess in all histologies except for meninge tumors (30–39 yo IRR: 0.71; 95% CI: 0.61, 0.84).ConclusionsIncidence of oligodendroglial and ependymal tumors increased globally in 20–39 yo suggesting better diagnoses or changes in risk factors. Males had a higher incidence of CNS tumors for most tumors studied and in most regions.     

Current status and recent trend of the Eurasian Woodcock Scolopax rusticola as a breeding bird in Britain

Capsule The breeding Woodcock population in Britain in 2013 was estimated at 55?241 males (95% CL: 41?806–69?004), suggesting a large-scale decline that is supported by 2 additional sources of data.

Aims To provide an updated estimate of the size of Britain's breeding Woodcock population, measure recent trends and identify spatial patterns of change.

Methods Displaying male Woodcock were surveyed at a stratified sample of 834 randomly selected sites. Population estimates were compared with a baseline survey conducted in 2003 and the trend with data from annual Woodcock counts (2003–13) and Bird Atlas 2007–11.

Results Woodcock were estimated to be present at 22% of 1?×?1?km squares containing ≥10?ha of woodland, compared to 35% in 2003. The British population estimate fell by 29% between 2003 and 2013. The Atlas suggests that presence at the 10?×?10?km scale has declined by 56% between 1970 and 2010. Both data sources suggest regional variation in the rate of decline, with losses greatest in the West and South.

Conclusion The Woodcock's population size and breeding range appear to be declining severely across Britain. Regional variation in the rate of decline might be explained by the distribution of large continuous woodlands.     

Recent changes in endometrial cancer trends among menopausal-age US women

BackgroundChanges in endometrial cancer incidence rates after the precipitous decline in menopausal hormone therapy (MHT) use in 2002 have not been evaluated.MethodsUsing data from the Surveillance, Epidemiology, and End Results Program from 1992 to 2009 (SEER 13), we identified 63 428 incident endometrial cancer cases among women ages 20–74. We compared annual percent change (APC) in endometrial cancer incidence rates from 1992 to 2002 to rates from 2003 to 2009.ResultsIn contrast to the constant endometrial cancer rate pattern observed from 1992 to 2002 (APC 0.0%), rates increased after 2002 in women 50–74 years old (2.5%; P_{APC comparison} < 0.01). Endometrial cancer incidence increased over the entire time period among women ages 20–49 (1992–2002: 1.1%; 2003–2009: 2.1%; P_{APC comparison} = 0.21). Post-2002 increases in incidence among women ages 50–74 were specific to Type I endometrial tumors (1992–2002: ?0.6%; 2003–2009: 1.6%; P_{APC comparison} < 0.01).DiscussionThe increase in endometrial cancer incidence rates after 2002 may be related to the widespread decrease in estrogen plus progestin MHT use, which has been reported to lower endometrial cancer risk in overweight and obese women.     

Weight at Birth and Subsequent Fecundability: A Prospective Cohort Study

Objective

To examine the association between a woman''s birth weight and her subsequent fecundability.

Method

In this prospective cohort study, we included 2,773 Danish pregnancy planners enrolled in the internet-based cohort study “Snart-Gravid”, conducted during 2007–2012. Participants were 18–40 years old at study entry, attempting to conceive, and were not receiving fertility treatment. Data on weight at birth were obtained from the Danish Medical Birth Registry and categorized as <2,500 grams, 2,500–2,999 grams, 3,000–3,999 grams, and ≥4,000 grams. In additional analyses, birth weight was categorized according to z-scores for each gestational week at birth. Time-to-pregnancy measured in cycles was used to compute fecundability ratios (FR) and 95% confidence intervals (CI), using a proportional probabilities regression model.

Results

Relative to women with a birth weight of 3,000–3,999 grams, FRs adjusted for gestational age, year of birth, and maternal socio-demographic and medical factors were 0.99 (95% CI: 0.73;1.34), 0.99 (95% CI: 0.87;1.12), and 1.08 (95% CI: 0.94;1.24) for birth weight <2,500 grams, 2,500–2,999 grams, and ≥4,000 grams, respectively. Estimates remained unchanged after further adjustment for markers of the participant''s mother''s fecundability. We obtained similar results when we restricted to women who were born at term, and to women who had attempted to conceive for a maximum of 6 cycles before study entry. Results remained similar when we estimated FRs according to z-scores of birth weight.

Conclusion

Our results indicate that birth weight appears not to be an important determinant of fecundability.     

Performance of Saxifraga hirculus L. in North-East Scotland as measured by counts of inflorescences

Summary

Saxifraga hirculus, the yellow marsh saxifrage, is a rare protected species growing in baserich flushes. For conservation, better knowledge is needed on its performance and habitat preferences, hence three colonies in the Cabrach district of Aberdeenshire have been monitored closely over the past eleven years. Additionally observations are reported on flowering at a ‘recovery site’ to which saxifrage Plants have been transplanted.

At one of the natural colonies S. hirculus has clearly increased, at another there has been decline, and at the third so many inflorescences are removed by grazing that the trend could not be decided. The increase, as measured by flowering, was associated with moderately heavy grazing that maintained sward height at about 20–25 cm in summer. The decrease in saxifrage flowering was associated with light grazing and a sward of 35–40 cm height; however drought conditions in 2003 were perhaps responsible, affecting the water table of this colony more than the other colonies due to site topography.

At the third colony water voles (Arvicola amphibious) have been regularly present, and have clear impact on the vegetation around their holes. It is suggested that the voles eat the flowering shoots of the saxifrage.     

Marked increase in breast cancer incidence in young women: A 10-year study from Northern Iran, 2004–2013

IntroductionBreast cancer is the most frequent cancer among women worldwide. Breast cancer incidence in young women is a health issue of concern, especially in middle-income countries such as Iran. The aim of this study is to report the breast cancer incidence variations in Golestan province, Iran, over a 10-year period (2004–2013).MethodsWe analyzed data from the Golestan Population-based Cancer Registry (GPCR), which is a high-quality cancer registry collecting data on primary cancers based on standard protocols throughout the Golestan province. Age-standardized incidence rates (ASRs) and age-specific incidence rates per 100,000 person-years were calculated. Time trends in ASRs and age-specific rates were evaluated using Joinpoint regressions. The average annual percentage change (AAPC) with correspondence 95% confidence intervals (95%CIs) were calculated.ResultsA total of 2106 new breast cancer cases were diagnosed during the study period. Most cases occurred in women living in urban areas: 1449 cases (68%) versus 657 cases (31%) in rural areas. Statistically significant increasing trends were observed over the 10-year study period amongst women of all ages (AAPC = 4.4; 95%CI: 1.2–7.8) as well as amongst women in the age groups 20–29 years (AAPC = 10.0; 95%CI: 1.7–19.0) and 30–39 years (AAPC = 5.1; 95%CI: 1.4–9.0).ConclusionThe incidence of breast cancer increased between 2004 and 2013 in Golestan province amongst all age groups, and in particular amongst women aged 20–39 years. Breast cancer should be considered a high priority for health policy making in our community.     

An examination of factors influencing black fertility decline in the Mississippi Delta, 1880–1930

Abstract

Although the fertility decline in the black population in the Mississippi Delta between the late 1870's and early 1930's closely paralleled that of the national black population, it rose much more dramatically in the 1940's and 1950's to almost 1880 levels. Given the especially rural and oppressed conditions of blacks there, the initial decline seems puzzling. Low fertility rates in the 1930's reflected a large proportion of childless females. Investigations of changing contraceptive usage and mate exposure suggest both were minor components at most. Several physiological impairments were investigated including dietary deficiences, malaria, tuberculosis, and sexually transmitted diseases (STD). Evidence suggests STD played the major role, facilitated by nutritional and other health problems. Models relying heavily on those developed by McFalls and McFalls (1984) suggest 50–80 percent of the decline could have been due to the spread of STD. Age‐specific birth rates for different periods and post‐World‐War‐II fertility increases seem consistent with this finding.     

Effects of food deprivation on Latrodectus hasselti Thorell (Araneae: Theridiidae), the Australian redback spider

Abstract

Food deprivation tests indicate that most sub-adult and adult female Latrodectus hasselti spiders would be able to endure long periods of starvation if incarcerated in cargo. The data show that, under appropriate conditions, sub-adults survive for up to 160 days and some adults for more that 300 days. Temperature is an important variable with longevity being greatest at 10°C and markedly reduced at 25°C. Sluggishness is more pronounced at lower temperatures and probably reflects reduced metabolic rates. Even after 2–3 months without food, most spiders recover when fed.

Five stages mark the progress of starvation (Indices of Starvation) and reflect a gradual decline in the spider’s normal functions. As the abdomen shrinks, with a concomitant loss of hydraulic pressure, there is a gradual decline in web-building and locomotory activities which ultimately end in the spider’s death. It is assumed that nutritional deficiency and, to a lesser extent, dehydration contribute to mortality.     

Mortality and smoking in Hong Kong: case-control study of all adult deaths in 1998

ObjectiveTo assess the mortality currently associated with smoking in Hong Kong, and, since cigarette consumption reached its peak 20 years earlier in Hong Kong than in mainland China, to predict mortality in China 20 years hence.DesignCase-control study. Past smoking habits of all Chinese adults in Hong Kong who died in 1998 (cases) were sought from those registering the death.SettingAll the death registries in Hong Kong.Participants27 507 dead cases (81% of all registered deaths) and 13 054 live controls aged ⩾35 years.ResultsIn men aged 35-69 the adjusted risk ratios (and 95% confidence intervals) comparing smokers with non-smokers were 1.92 (1.70 to 2.16) for all deaths, 2.22 (1.94 to 2.55) for neoplastic deaths, 2.60 (2.10 to 3.21) for respiratory deaths (including tuberculosis, risk ratio 2.54), and 1.68 (1.43 to 1.97) for vascular deaths (each P<0.0001). In women aged 35-69 the corresponding risk ratios were 1.62 (1.40 to 1.88) for all deaths, 1.60 (1.33 to 1.93) for neoplastic deaths, 3.13 (2.21 to 4.44) for respiratory deaths, and 1.55 (1.20 to 1.99) for vascular deaths (each P<0.001). If these associations with smoking are largely or wholly causal then, among all registered deaths at ages 35-69 in 1998, tobacco caused about 33% (2534/7588) of all male deaths and 5% (169/3341) of all female deaths (hence 25% of all deaths at these ages). At older ages tobacco seemed to be the cause of 15% (3017/20 420) of all deaths.ConclusionsAmong middle aged men the proportion of deaths caused by smoking is more than twice as big in Hong Kong now (33%) as in mainland China 10 years earlier. This supports predictions of a large increase in tobacco attributable mortality in China as a whole.

What is already known on this topic

China, with 20% of the world''s population, smokes 30% of the world''s cigarettes. Men smoke most, and the proportion of male deaths at ages 35-69 attributable to tobacco has been predicted to rise over the next few decades from 13% (in 1988) to about 33%In Hong Kong cigarette consumption reached its peak 20 years earlier than in mainland China, so the epidemic of male deaths from tobacco should now be at a more advanced stage

What this study adds

In the general population of Hong Kong in 1998 tobacco caused about 33% of all male deaths at ages 35-69 plus 5% of all female deaths, and hence 25% of all deaths at these agesIn the male smokers tobacco caused about half of all deaths at ages 35-69The hazards now seen in Hong Kong foreshadow a substantial increase in tobacco deaths among middle aged men in mainland China over the next few decades if current smoking patterns persist     

Association between disparities in intergenerational economic mobility and cause-specific mortality among Black and White persons in the United States

BackgroundEvidence about the association between structural racism and mortality in the United States is limited. We examined the association between ongoing structural racism, measured as inequalities in adulthood income between White and Black children with similar parental household income (economic mobility gap) in a recent birth cohort, and Black-White disparities in death rates (mortality gap) overall and for major causes.MethodsSex-, race/ethnicity-, and county-specific data were used to examine sex-specific associations between economic mobility and mortality gaps for all causes combined, heart diseases, cerebrovascular diseases, chronic obstructive pulmonary disease (COPD), injury/violence, all malignant cancers, and 14 cancer types. Economic mobility data for 1978–1983 birth cohorts and death rates during 2011–2018 were obtained from the Opportunity Atlas and National Center for Health Statistics, respectively. Data from 471 counties were included in analyses of all-cause mortality at ages 30−39 years during 2011–2018 (corresponding to partially overlapping 1978–1983 birth cohorts); and from 1,572 and 1,248 counties in analyses of all-cause and cause-specific mortality in all ages combined, respectively.ResultsIn ages 30−39 years, a one percentile increase in the economic mobility gap was associated with a 6.8 % (95 % confidence interval 1.8 %–11.8 %) increase in the Black-White mortality gap among males and a 13.5 % (8.9 %–18.1 %) increase among females, based on data from 471 counties. In all ages combined, the corresponding percentages based on data from 1,572 counties were 10.2 % (7.2 %–13.2 %) among males and 14.8 % (11.4 %–18.2 %) among females, equivalent to an increase of 18.4 and 14.0 deaths per 100,000 in the mortality gap, respectively. Similarly, strong associations between economic mobility gap and mortality gap in all ages were found for major causes of death, notably for potentially preventable conditions, including COPD, injury/violence, and cancers of the lung, liver, and cervix.ConclusionsEconomic mobility gap conditional on parental income in a recent birth cohort as a marker of ongoing structural racism is strongly associated with Black-White disparities in all-cause mortality and mortality from several causes.     

The effect of excision on O2 diffusion and metabolism in soybean nodules

Nitrogen-fixing nodules of soybean [Glycine max (L.) Merr. cv. Maple Arrow inoculated with Bradyrhizobium japonicum USDA 16] were studied before and after excision from the root to determine the role the O₂ regulation plays in the inhibition of nodule activity and the potential for using excised nodules nodules in studies of nodule metabolism. Relative nitrogenase (EC 1.7.99.2) activity (H₂ evolution in N₂:O₂) and nodule respiration (CO₂ evolution) were monitored first in intact nodulated roots and then in freshly excised nodules of the same plant to determine the time course of the decline in nodule metabolism. Folowing excision, nitrogenase activity and respiration declined rapidly in the first minute and then more gradually. After 40 min the rate of H₂ evolution was only 14–28% of that in the intact plant. In some nodules activity declined steadily, and in others there was a partial recovery in activity ca 10 min after detachment. Infected cell O₂ concentration (O_i), measured by a spectro-photometric technique, also declined after nodule detachment with a time course similar to the declines in nitrogenase activity and respiration. Following excision, O_i levels declined rapidly from ca 21 nM in attached nodules to 8–12 nM at 4–10 min after excision and then more gradually to 2–3 nM O₂ at 30–40 min after excision. These results show that the nodules' permeability to gas diffusion continued to be regulated for up to 40 min after detachement. At 40 min after detachment, when excised nodules displayed steady-state rates of gas exchange, linear increases in pO₂ from 20 to 100% at 4% min^?1 resulted in recoveries of H² and CO² evolution, indicating that O_i limited nitrogenase activity durig this period, and that energy reserves were greatly in excess of the O₂ available for respiration. When detached nodules were equilibrated for 12 h at 20, 30 and 50% O₂, O_i values measured at supra-ambient pO₂ were greater than those at 20% O₂ and were linked with a more rapid decline in nitrogenase activity. Also, increases in external pO₂ (O_c) failed to stimulate nodule metabolism, suggesting that the nodules' energy reserves were no longer greatly in excess of their respiratory demands. It was concluded that soybean nodules could provide useful material for steady-state studies of nodule metabolism between 40 and 240 min after detachment, but to attain metabolic rates equivalent to in vivo rates the nodules must be exposed to above-ambient pO₂.     

The ghost of Christmas past: health effects of poverty in London in 1896 and 1991

ObjectivesTo compare the extent to which late 20th century patterns of mortality in London are predicted by contemporary patterns of poverty and by late 19th century patterns of poverty. To test the hypothesis that the pattern of mortality from causes known to be related to deprivation in early life can be better predicted by the distribution of poverty in the late 19th century than by that in the late 20th century.DesignData from Charles Booth''s survey of inner London in 1896 were digitised and matched to contemporary local government wards. Ward level indices of relative poverty were derived from Booth''s survey and the 1991 UK census of population. All deaths which took place within the surveyed area between 1991 and 1995 were identified and assigned to contemporary local government wards. Standardised mortality ratios for various causes of death were calculated for each ward for all ages, under age 65, and over age 65. Simple correlation and partial correlation analysis were used to estimate the contribution of the indices of poverty from 1896 and 1991 in predicting ward level mortality ratios in the early 1990s.SettingInner London.ResultsFor many causes of death in London, measures of deprivation made around 1896 and 1991 both contributed strongly to predicting the current spatial distribution. Contemporary mortality from diseases which are known to be related to deprivation in early life (stomach cancer, stroke, lung cancer) is predicted more strongly by the distribution of poverty in 1896 than that in 1991. In addition, all cause mortality among people aged over 65 was slightly more strongly related to the geography of poverty in the late 19th century than to its contemporary distribution.ConclusionsContemporary patterns of some diseases have their roots in the past. The fundamental relation between spatial patterns of social deprivation and spatial patterns of mortality is so robust that a century of change in inner London has failed to disrupt it.     

Adolescent and young adult cancers in India–Findings from the National Cancer Registry Programme

BackgroundThe adolescent and young adult (AYA) age group is a bridge between pediatric and adult age groups. The present study describes the epidemiology of cancers in the AYA age group in India.MethodsThe data of primary site cancers in the age group of 15–39 years from the 28 Population Based Cancer Registries (PBCRs') and 58 Hospital Based Cancer Registries under the National Cancer Registry Programme for the reporting year 2012–2016 was analysed.ResultsThe median age adjusted incidence rate (AAR) was 22.2 per 100,000 among males and 29.2 per 100,000 among females. The age-specific incidence rate increased with increasing age in both genders with the highest recorded numbers in the 35–39 age group. The proportion of myeloid leukaemia and non-Hodgkin's lymphoma was highest in the 15–24 age group. Cancers of the breast, thyroid, mouth and tongue constituted the leading sites between 30 and 39 years. There was a significant increase in the incidence among AYA males (APC=0.9) between 1985 and 2015, while a decline in incidence was observed for females, which was not significant (APC=−0.2). The majority of patients had locoregional spread of cancer at the time of diagnosis. The projected number of cancer cases in both genders are expected to increase to 178,617 in 2025.ConclusionCancers in the AYA population are a concern in India. Since AYA oncology appears to be evolving in India, a robust health care system and suitable AYA cancer care policies and programmes are strongly needed to improve disease outcomes and survival.     

The palatability of flavoured novel floating pellets made with brewer's spent grain to captive carp

Abstract

The palatability to common carp, Cyprinus carpio L. of three newly developed differently flavoured floating pellets made from a high proportion (40%) of brewer's spent grain (BSG) was tested using a multiple-offer feeding experiment. The addition of ‘bold’ flavours, such as vanilla or strawberry essence, may help mask the unpleasant taste of some piscicides; however, their inclusion must not compromise uptake by carp. There were no significant differences between the consumption rates of the three varieties, and all flavours were readily consumed. Therefore, it is suggested that highly flavoured pellets made with BSG have a strong potential to mask the flavour of an unpalatable toxin, and further research is now needed to test this hypothesis.