Late Fertility Research Articles

Gestational weight gain and fetal growth in underweight women.

BackgroundDespite the current obesity epidemic, maternal underweight remains a common occurrence with potential adverse perinatal outcomes.MethodsWe aimed to investigate the relationship between weight gain during pregnancy, and fetal growth in underweight women with low and late fertility. Women body mass index (BMI), defined according to the World Health Organization’s definition, gestational weight gain (GWG), defined by the Institute of Medicine and National Research Council and neonatal birth weight were prospectively collected at maternity ward of Policlinico Abano Terme (Italy) in 793 consecutive at term, uncomplicated deliveries.ResultsAmong those, 96 (12.1 %) were categorized as underweight (BMI < 18.5 kg/m2), 551 (69.5 %) as normal weight, 107 (13.4 %) as overweight, and 39 (4.9 %) as obese, respectively. In all mother groups, GWG was within the range recommended by IOM 2009 guidelines. However, underweight women gained more weight in pregnancy (12.8 ± 3.9 kg) in comparison to normal weight (12.3 ± 6.7 kg) and overweight (11.0 ± 4.7 kg) women and their GWG was significantly higher (p < 0.001) with respect to obese women 5.8 ± 6.1 kg). In addition, offspring of underweight women were comparable in size at birth to offspring of normal weight women, whereas they were significantly lighter to offspring of both overweight and obese women.ConclusionsPre-pregnancy underweight does not impact birth weight of healthy, term neonates in presence of normal GWG. Presumably, medical or personal efforts to reach ‘optimal’ GWG could be a leading choice for many women living in industrialized and in low-income countries.

Effect of dry mycelium of Penicillium chrysogenum fertilizer on soil microbial community composition, enzyme activities and snap bean growth.

The dry mycelium fertilizer (DMF) was produced from penicillin fermentation fungi mycelium (PFFM) following an acid-heating pretreatment to degrade the residual penicillin. In this study, it was applied into soil as fertilizer to investigate its effects on soil properties, phytotoxicity, microbial community composition, enzyme activities, and growth of snap bean in greenhouse. As the results show, pH, total nitrogen, total phosphorus, total potassium, and organic matter of soil with DMF treatments were generally higher than CON treatment. In addition, the applied DMF did not cause heavy metal and residual drug pollution of the modified soil. The lowest GI values (<0.3) were recorded at DMF8 (36kg DMF/plat) on the first days after applying the fertilizer, indicating that severe phytotoxicity appeared in the DMF8-modified soil. Results of microbial population and enzyme activities illustrated that DMF was rapidly decomposed and the decomposition process significantly affected microbial growth and enzyme activities. The DMF-modified soil phytotoxicity decreased at the late fertilization time. DMF1 was considered as the optimum amount of DMF dose based on principal component analysis scores. Plant height and plant yield of snap bean were remarkably enhanced with the optimum DMF dose.

Consanguinity and late fertility: spatial analysis reveals positive association patterns.

The role of consanguinity on human complex traits is an important and controversial issue. In this work we focused on the Sardinian population and examined the effect of consanguineous unions on late female fertility. During the last century the island has been characterized by a high incidence of marriages between relatives, favoured by socio economic conditions and geographical isolation, and by high fertility despite a widespread tendency to delay reproduction. Through spatial analysis techniques, we explored the geographical heterogeneity of consanguinity and late fertility, and identified in Central-Eastern Sardinia a common area with an excess of both traits, where the traits are positively associated. We found that their association did not significantly affect women's fertility in the area, despite the expected negative role of both traits. Intriguingly, this critical zone corresponds well to areas reported by previous studies as being peculiar for a high frequency of centenarians and for lower risk in pregnancy outcome. The proposed approach can be generally exploited to identify target populations on which socioeconomic, biodemographic and genetic data can be collected at the individual level, and deeper analyses carried out to disentangle the determinants of complex biological traits and to investigate their association.

Happiness: before and after the kids.

Understanding how having children influences parents' subjective well-being ("happiness") has great potential to explain fertility behavior. We study parental happiness trajectories before and after the birth of a child, using large British and German longitudinal data sets. We account for unobserved parental characteristics using fixed-effects models and study how sociodemographic factors modify the parental happiness trajectories. Consistent with existing work, we find that happiness increases in the years around the birth of a first child and then decreases to before-child levels. Moreover, happiness increases before birth, suggesting that the trajectories may capture not only the effect of the birth but also the broader process of childbearing, which may include partnership formation and quality. Sociodemographic factors strongly modify this pattern. Those who have children at older ages or who have more education have a particularly positive happiness response to a first birth; and although having the first two children increases happiness, having a third child does not. The results, which are similar in Britain and Germany, suggest that having up to two children increases happiness, and mostly for those who have postponed childbearing. This pattern is consistent with the fertility behavior that emerged during the second demographic transition and provides new insights into low and late fertility.

Socioeconomic fertility differentials in a late transition setting: A micro-level analysis of the Saguenay region in Quebec

AbstractBACKGROUNDHistorically, the French Canadian population of Quebec, Canada, is known for its high fertility, which lasted well into the 20th century, and for its late fertility transition. Within Quebec, regions such as Saguenay are known for having experienced an even more delayed fertility transition.OBJECTIVEIn Quebec, as elsewhere, various factors modulated the transition, and differential behaviors and timing can be observed across socioeconomic groups. These factors are studied here in the context of the Saguenay region, where particularly rich data are available. The region was mostly rural at first, but industrialization and urbanization occurring since the beginning of the 20th century allow us to study socioeconomic reproductive differentials before and during the transition.METHODSTo do so, we rely on the BALSAC database, which contains all church and civil records from the onset of colonization around 1840 up to 1971. In addition to the usual descriptive statistics, we use Cox models to analyze the probability of having a first birth and higher order births among four socioeconomic groups defined with HISCLASS coding.RESULTSThe results demonstrate the late timing of the and a clear progression from the non-manual and skilled workers, who show the first signs of declining fertility during the 1930s, to the farmers, who do the same only at the end of the 1950s. As a result, socioeconomic fertility differentials widened during the period.CONCLUSIONEven in a context where the was significantly delayed compared to most other regions studied in this issue, some socioeconomic differentials were observed prior to the transition, and they widened during the due to the differential progression of contraceptive practices among couples.1. IntroductionThe study of socioeconomic stratification and fertility before, during and the has raised various issues that are discussed in the vast literature about the relationship between socioeconomic factors and fertility behavior. Three of these issues are of particular interest to us: first, the role of socioeconomic explanations in understanding the fertility transition; second, the existence of socioeconomic stratification before the transition; and, third, the evolution of socioeconomic differentials during the fertility transition. The Saguenay region being studied was on the verge of reaching its after the transition phase in 1971, which means we cannot consider this last phase with the data used in this paper.After many decades of competing theories placing emphasis on economic or cultural explanations for the fertility in Western societies, in which the works of Thompson (1929), Notestein (1945), Coale (1973), Easterlin (1978), Caldwell (1982), Coale and Watkins (1986), Lesthaeghe and Wilson (1982), and Lesthaeghe and Surkyn (1988) occupy a prominent place, one can say that some consensus has been reached about the importance of both types of explanation and about the specificity of their combined effect in various contexts. Some even argued that socioeconomic factors underpinned the fertility transition, while cultural determinants largely conditioned its pace in various contexts (for example, Lesthaeghe and Wilson 1982). Despite the unique features of the fertility (and demographic) in each society, it is also acknowledged that using comparative approaches can further enhance our understanding of crucial aspects of the fertility transition, and this certainly includes the need for a careful examination of the role of socioeconomic factors in various settings.The question of whether a socioeconomic stratification of fertility behavior existed prior to the has been fueled recently by the very detailed work undertaken by Tsuya et al. (2010) in various parts of Europe (Sweden, Belgium, Italy) and Asia (Japan, China) using sophisticated techniques applied to detailed micro-level data. …

Analysis of the floral transcriptome of Tarenaya hassleriana (Cleomaceae), a member of the sister group to the Brassicaceae: towards understanding the base of morphological diversity in Brassicales

BackgroundArabidopsis thaliana, a member of the Brassicaceae family is the dominant genetic model plant. However, while the flowers within the Brassicaceae members are rather uniform, mainly radially symmetrical, mostly white with fixed organ numbers, species within the Cleomaceae, the sister family to the Brassicaceae show a more variable floral morphology. We were interested in understanding the molecular basis for these morphological differences. To this end, the floral transcriptome of a hybrid Tarenaya hassleriana, a Cleomaceae with monosymmetric, bright purple flowers was sequenced, annotated and analyzed in respect to floral regulators.ResultsWe obtained a comprehensive floral transcriptome with high depth and coverage close to saturation analyzed using rarefaction analysis a method well known in biodiversity studies. Gene expression was analyzed by calculating reads per kilobase gene model per million reads (RPKM) and for selected genes in silico expression data was corroborated by qRT-PCR analysis. Candidate transcription factors were identified based on differences in expression pattern between A. thaliana and T. hassleriana, which are likely key regulators of the T. hassleriana specific floral characters such as coloration and male sterility in the hybrid plant used. Analysis of lineage specific genes was carried out with members of the fabids and malvids.ConclusionsThe floral transcriptome of T. hassleriana provides insights into key pathways involved in the regulation of late anthocyanin biosynthesis, male fertility, flowering time and organ growth regulation which are unique traits compared the model organism A. thaliana. Analysis of lineage specific genes carried out with members of the fabids and malvids suggests an extensive gene birth rate in the lineage leading to core Brassicales while only few genes were potentially lost during core Brassicales evolution, which possibly reflects the result of the At-β whole genome duplication. Our analysis should facilitate further analyses into the molecular mechanisms of floral morphogenesis and pigmentation and the mechanisms underlying the rather diverse floral morphologies in the Cleomaceae.

Exploring Sardinian longevity: women fertility and parental transmission of longevity

The aims of this study are to analyse the two-way association between women fertility and longevity, and parental transmission of longevity. The wealth of information gathered in the AKeA2&#x2014;demographic survey on Sardinian centenarians&#x2014;have been used by applying Logistic Regression Models. For the association between longevity and fertility, we find evidence that *long livers benefit from factors related to the timing of fertility (in particular the age at birth of the last child) that the literature suggests may foster longevity. Regarding the association with parental transmission, it seems to have significant effects for women but not for men. We always found that a higher birth order decreases the probability of becoming a centenarian. There is a negative effect of a higher father age at birth on the longevity of female offspring. The latter suggests that long-lived women seem to have been favoured both by their own late fertility and young paternal age at the moment of their own procreation.

Production of Rice as Animal Feed by Late Fertilizer Application to Suppressing Rice Blast Disease

Production of Rice as Animal Feed by Late Fertilizer Application to Suppressing Rice Blast Disease

Coping strategies in low-risk pregnant women: the influence of low and late fertility

Objective: Socio-demographic factors were strongly associated with coping styles in pregnant women. We studied fertility postponement, a new increasing phenomenon in industrialized countries.Method: We studied coping (The Coping Inventory for Stressful Situations, CISS) in 341 healthy pregnant women, with a median age of 34 years (IQR 31–36), in their third trimester, living in Veneto, region of Italy which emerges for its low and late fertility.Results: Task-oriented coping was the most frequently used coping styles (Median, IQR: 48, 44–53), followed by Emotion-oriented coping (Median, IQR: 44, 39–49). Avoidance-oriented coping with subscales Social Diversion and Distraction were used least frequently (Median, IQR: 44, 38–49; 21, 18–24, and 14, 12–16, respectively). Socio-demographic factors were not associated with coping styles, but maternal age was inversely correlated with task coping (Spearman coefficient rho = −0.13, p = 0.02).Conclusion: Fertility postponement leads to the selection and use of ineffective coping strategies in an effort to alleviate anxiety.

Cohabitation in Spain: No Longer a Marginal Path to Family Formation

Although many indicators reflect the marked retreat from marriage occurring in Spain since the 1980s, the diffusion of cohabitation has been slow. The confluence of very low and late fertility, latest‐late marriage, and low cohabitation has been largely regarded as defying the predictions of the second demographic transition and has fueled a debate over the distinctiveness of the Mediterranean model of family formation. Comparative analyses based on the Family and Fertility Survey documented the marginal role of cohabitation in Spain and in the rest of southern European countries by the mid‐1990s. In this research, the authors used more recent data from the 2006 Spanish Fertility, Family and Values Survey (N = 5,750) to reveal that cohabitation has spread significantly among younger cohorts and hence can no longer be considered as playing a marginal role in the family formation process.

Birth Rate and the Proportion of Vietnamese Women Having a Third Child in the Period 1999 - 2009

 Abstract—Using the statistics from General Statistical Office, the paper will present the findings of birth rate and the proportion of Vietnamese women having a third child in the period 1999 - 2009. The birth rate has substantially declined (from 2.33 children in 1999 to 2.03 children in 2009) and reached the sub-replacement fertility rate over the past years. The fertility rate in rural areas decreases faster than in urban one, however it is still higher (1.81 children in urban versus 2.14 children in rural in 2009). The Central Highlands has the highest fertility rate in the country (2.65 children in 2009), and Mekong River Delta has the lowest rate (1.84 children in 2009). In recent years, the fertility rate of ethnic minorities is not a very big difference compared with that of Kinh group, apart from the excessively higher fertility rate of H'Mong women. Similarly, there only exists a slight difference in the fertility rate of different religious groups. Women's education level has an obvious impact on the fertility rate. The higher their education level is, the lower the fertility rate is and vice versa. Women with high school graduation had the lowest of fertility rate (1.64 children), whereas the highest (2.65 children) was of illiterate women. Fertility rate is also directly proportional to the rate of using contraceptive methods. The more couples use contraceptive methods, the lower the fertility rate becomes. In terms of age specific fertility rate, it can be clearly recognized that Vietnam's fertility model has continued transforming from early fertility to late fertility. During the last years, Vietnam has tried their best to encourage families to stop giving birth to a third child. We have obtained some certain success such as awarded by the United Nations for the fast decline of population development rate in 1999, however there still exists the problem of couple giving birth to a third child, especially in some geographic regions: Northern Midlands and Mountainous (Northeast and Northwest), and the Central Highlands, this rate tends to increase.

Social age deadlines for the childbearing of women and men

BACKGROUNDThis study examines whether social age deadlines exist for childbearing in women and men, how they vary across countries, whether they are lower than actual biological deadlines and whether they are associated with childbearing at later ages and the availability of assisted reproduction techniques (ARTs).METHODSThis study is based on the European Social Survey, Round 3 (2006–2007), which covers 25 countries. Data were gathered on social age deadlines for childbearing in women (21 909 cases) and men (21 239 cases) from samples of representative community-dwelling populations aged 15 and older.RESULTSSocial age deadlines for childbearing were perceived more frequently for women than men. These deadlines are often lower than actual biological limits, and for women and men alike: 57.2% of respondents perceived a maternal social age deadline ≤40 years of age; 46.2% of the respondents perceived a paternal social age deadline ≤45 years of age. There is also considerable variability in deadlines across countries, as well as within them. At the country level, the presence of social age deadlines for the childbearing of women was negatively associated with birth rates at advanced ages and the prevalence of ART, and later deadlines were positively associated with these factors.CONCLUSIONSIt is important to understand the factors that increase and limit late fertility. While biological factors condition fertility, so do social expectations. These findings provide widespread evidence across Europe that social limits exist alongside biological ones, though both sets of factors are more binding for women.

“Reproductive aging in captive and wild common chimpanzees: factors influencing the rate of follicular depletion,” by S. Atsalis and E. Videan, American Journal of Primatology 71, 271–282 (2009)

Atsalis and Videan [2009] conclude that the ‘‘occurrence of a postreproductive life span [is] more evident in some species of captive populations that can live for a long time beyond what is foreseen by the follicular store.’’ Specifically, they contend that captivity causes chimpanzees to undergo more ovulations than do chimpanzees in the wild, so that they experience menopause earlier. Central to this contention is the premise that ‘‘despite the increased longevity generally observed in captive populations reproductive life span is shortened.’’ We point out in this commentary that most published evidence on the timing of menopause in chimpanzees, including our own work, contradicts this premise, instead suggesting that menopause occurs late in the life span of the captive chimpanzee. The authors cite Emery Thompson et al. [2007] as support for their claim that chimpanzees reproduce into their 40s in the wild. The conclusion that menopause has occurred by age 40 in captive chimpanzees is based upon a study by Videan et al. [2006], which claimed that menopause occurs at 35–40 years of age in the chimpanzees. This conclusion was not based upon observation of menses or cycles of ovulation, but rather upon determination of gonadotrophin levels in two samples each year obtained from 14 female chimpanzees, 3 of which were over the age of 40. The criterion for menopause was the presence of FSH levels greater than 14 IU/ mL. The conclusion that menopause is reached between 35 and 40 years of age was based upon mean FSH in each age group. Studies using other methods have reached different conclusions. The first published study on reproductive aging in captive chimpanzees [Graham, 1979] examined ten female chimpanzees aged 35–48 years old at the Yerkes National Primate Research Center (YNPRC). At least one menstrual cycle was observed within 1 year of death in each of these individuals. In a subsequent study, also conducted at the YNPRC, Gould et al. [1981] observed two common chimpanzees and one bonobo over the age of 40. They concluded that the bonobo (Pan paniscus) was menopausal, based on cessation of menses and anogenital swelling, elevated gonadotropins and ovarian histology. Unfortunately, the precise age of this individual was unknown. Importantly, the two common chimpanzees (Pan troglodytes) continued to experience menstrual cyclicity at ages 48 and 50. Our larger study of menstrual cycles in 89 chimpanzees at the YNPRC [Lacreuse et al., 2008] confirms the findings of Gould et al. [1981] and contradicts the findings of the Videan et al. [2006]. Our study was based upon observations of cycles of menstrual bleeding and included observations of 20 individuals past the age of 40 years; all 20 of these individuals displayed menstrual cycles after the age of 40; one chimpanzee gave birth at the age of 42, two years past the age suggested as the age of menopause for captive chimpanzees. Since this birth occured in the same year (1997) that the US moratorium on chimpanzee breeding was begun, we do not know whether births may have occurred at even later maternal ages. Indeed, a recent paper reports that a chimpanzee in a zoo in Switzerland gave birth to a healthy infant at a documented age of 49 years; this chimpanzee’s only other infant (to date!) was born when the mother was 42 [Puschmann & Federer, 2008]. This late fertility is consistent with our population at YNPRC, where

Utilization of internet-based survivorship care plans by breast cancer survivors.

Abstract Abstract #1122 Background: In the past three decades, the number of cancer survivors living in the United States has more than tripled (MMWR 2004). Survivors of breast cancer represent a large and important subset of this population, and remain at risk for late-effects such as heart disease and second malignancy (Harris 2006, Schaapveld 2008). Multiple groups have shown survivor care to be inadequate, and the Institute of Medicine has identified a need for survivorship care plans (SCP) for all cancer survivors. Here, we describe use patterns of the first personalized web-based SCP by breast cancer survivors.&amp;#x2028; Methods: A program for creation of SCP, OncoLife , was made publicly accessible through OncoLink (www.oncolink.org), a website serving over 3.9 million pages/month to 385,000 unique IP addresses (Aug 2007) and based at the University of Pennsylvania. Data was maintained anonymously, and collection and analysis processes were reviewed by the institutional IRB. Users responded to queries regarding demographics, diagnosis, and treatment, and received comprehensive, individualized guidelines for future care addressing issues such as late toxicity, second malignancy, fertility, and tumor recurrence.&amp;#x2028; Results: From 5/07-5/08, 2573 individuals completed OncoLife surveys. Users described themselves as cancer survivors (66%), family members/friends of survivors (12%) and healthcare providers (23%), and identified themselves as residents of 46 states and 15 countries. Median age at cancer diagnosis was 48 years (yrs) (range 18–100), and median current age 51 yrs (range 19– &amp;gt;100). Breast cancer survivors composed 45% of the population of OncoLife users (n=1164), and were predominantly female (96%), Caucasian (97%), and well-educated, with 81% having education beyond high school. Median age at breast cancer diagnosis was 47 yrs (range 18–93), and median current age 51 yrs (range 19-94). Nearly all breast cancer survivors (97%) had undergone surgery, while 75% were treated with radiation, and 85% intravenous chemotherapy (most commonly cyclophosphamide, doxorubicin, and/or taxols). Hormonal treatments were delivered to 66% of survivors, and trastuzumab to 11%. Of breast cancer survivors, 56% described receiving follow-up care only from an oncologist, 12% only from a primary care provider, and 30% from both. Only 14% of breast cancer survivors reported having ever before been offered information on survivorship care.&amp;#x2028; Conclusions: OncoLife represents the first web-based program for creation of SCP, and patients and healthcare providers appear willing to use this type of tool. Most breast cancer survivors have undergone multimodality care, placing them at risk for late-effects. Most do not receive formal survivorship care information after active cancer therapy, so attention to survivor needs by the oncology community is important. Future versions of OncoLife will focus on expanding healthcare provider and Spanish versions, and increasing accessibility to underserved populations. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1122.

Potassium leaching from cut grassland and from urine patches

AbstractIn grassland farming, especially on coarse‐textured soils, K can be a critical element. On these soils, the actual K management as well as fertilizer history to a large extent determine the leaching of K. The effects of four fertilizer regimes on the nutrient balances and leaching of K from grassland grown on a sandy soil were investigated. The swards differed in the source and level of N input and K fertilizer: no fertilizer N + 166 kg K ha−1 year−1 (Control), 320 kg inorganic N ha−1 + 300 kg K ha−1 year−1 (MIN 320), 320 kg N + 425 kg K ha−1 year−1 in form of cattle slurry (SLR 320) and a grass–clover sward + 166 kg K ha−1 year−1 (WCL 0) without any inorganic N input. In a second experimental phase, cores from these swards were used in a mini‐lysimeter study on the fate of K from urine patches. On cut grassland after 6 years K input minus removal in herbage resulted in average K surpluses per year of 47, 39, 56 and 159 kg K ha−1 for the Control, MIN 320, WCL 0 and SLR 320, respectively. Related leaching losses per year averaged 7.5, 5, 15 and 25 kg K ha−1. Losses of urinary‐K through leaching were 2.2–4.5 and 5.7–8.4% of the K supplied in summer and autumn applications, respectively. Plant and soil were the major sinks for K from fertilizer or urine. High levels of exchangeable K in the soil and/or large and late fertilizer or urine applications stimulated leaching of K.

THE INFLUENCE OF MATERNAL CARE IN SHAPING HUMAN SURVIVAL AND FERTILITY

The influence of maternal care on child survival has evolved throughout human history due to variation in altriciality, allocare, and maternal behaviors. Here, we study the impact of these factors on the force of selection acting on age-specific survival and fertility (measured with elasticity analysis) in a model that incorporates the dependence of child survival on maternal survival. Results reveal life-history changes that cannot be elucidated when considering child's survival independent of maternal survival: decrease of late fertility and increase of late survival, and concomitant decrease of early and late fertility. We also show that an increase of child altriciality in early humans might explain the main human life-history traits: a high life expectancy and postreproductive life; a long juvenile period and a higher, and narrowed, fertility at the peak of the reproductive period.

Under the Shadow of the Collective Good

Before the government instituted birth control policies, did Chinese families deliberately control birth and fertility? Some scholars believe that natural fertility was indeed a fact in Chinese population history; others argue that the Chinese controlled their fertility by such positive checks as late fertility onset, early stopping of reproduction, and long intervals between births. This article joins the debate by providing ethnographic data collected in Xiaoshan, Zhejiang, in 2002. The ethnographic case studies show that deliberate fertility limitation did exist in both rural and urban communities in Xiaoshan. In addition, the article challenges the assumption that Chinese fertility was shaped by collective control rather than individual interests. On the contrary, it demonstrates that the agency of individuals, particularly of women, was often the driving force in family reproduction.

Approaching the Limit: Long‐Term Trends in Late and Very Late Fertility

In this article we discuss trends in the limits to late childbearing, their determinants and potential implications from an empirical long-term perspective. Although the high levels observed in non-contracepting populations have not been reached, fertility in Europe at ages 40+ and 45+ has increased substantially in recent years. This trend received considerable attention, especially in combination with the emergence of new reproductive technologies and often low levels of general fertility. Nevertheless, physiological studies agree on the fact that age limits to childbearing, at least for women, have not shifted to later ages. Our empirical analyses of high-quality long-term data from Sweden document an increase in the absolute and relative number of births at ages 40+ and 45+, together with an increase in first birth occurrence-exposure rates at ages close to 40.

Late fertility in Europe: some comparative and historical data

Given the substantial increase in late fertility (at ages 35 and older) in the last few years in Western countries, the paper raises the question of what factors have caused this new trend, and how likely it is to continue. Late fertility is measured using the sum of age-specific fertility rates at 35 or more; its contribution to the total fertility rate (in % of the total fertility rate) and the proportion of first childbirths in this fertility is then computed. Late fertility among men is assessed using the same method, where the necessary data are available. The data analysed sometimes date back to the 18th century for women (Sweden), and the early 20th century for men (in France). Late fertility is now much lower than it used to be. Despite the current increase--which can be traced back to the early 1980s for most Western countries, and appears to be much more recent and limited in the former socialist countries--current levels are very low compared with those of the past, among men as well as women. Reduced family size was the main factor in that decline, which became more pronounced as a result of women having a first child at younger ages. The reversal of the trend is due only to postponed childbearing, which must be viewed as part of a general trend towards postponement of all demographic events. More and more of the children born in such circumstances are thus first children. Very late fertility (at 40 or more) has increased, though only slightly, for men as well as women, and age 45 seems to be a limit beyond which few are prepared to have children. Social norms concerning the age limit for a person to have a child could account for the differences from one country to another in that respect. Late fertility is likely to continue increasing as long as fertility continues to decrease among young people. However, the increase will continue to be due mostly to the "younger" age groups (under 40 for women, under 45 for men); both biological constraints and social norms probably play a part in the stagnation of very late fertility levels.

Environmental effects on progesterone profile measures of dairy cow fertility

Environmental effects on fertility measures early in lactation, such as the interval from calving to first luteal activity (CLA), proportion of samples with luteal activity during the first 60 days after calving (PLA) and interval to first ovulatory oestrus (OOE) were studied. In addition, traditional measurements of fertility, such as pregnancy to first insemination, number of inseminations per service period and interval from first to last insemination were studied as well as associations between the early and late measurements. Data were collected from an experimental herd during 15 years and included 1106 post-partum periods from 191 Swedish Holsteins and 325 Swedish Red and White dairy cows. Individual milk progesterone samples were taken twice a week until cyclicity and thereafter less frequently. First parity cows had 14.8 and 18.1 days longer CLA (LS-means difference) than second parity cows and older cows, respectively. Moreover, CLA was 10.5 days longer for cows that calved during the winter season compared with the summer season and 7.5 days longer for cows in tie-stalls than cows in loose-housing system. Cows treated for mastitis and lameness had 8.4 and 18.0 days longer CLA, respectively, compared with healthy cows. OOE was affected in the same way as CLA by the different environmental factors. PLA was a good indicator of CLA, and there was a high correlation (−0.69) between these two measurements. Treatment for lameness had a significant influence on all late fertility measurements, whereas housing was significant only for pregnancy to first insemination. All fertility traits were unfavourably associated with increased milk production. Regression of late fertility measurements on early fertility measurements had only a minor association with conception at first AI and interval from first to last AI for cows with conventional calving intervals, i.e. a 22 days later, CLA increased the interval from first to last insemination by 3.4 days. Early measurements had repeatabilities of 0.14–0.16, indicating a higher influence by the cow itself compared with late measurements, which had repeatabilities of 0.09–0.10. Our study shows that early fertility measurements have a possibility to be used in breeding for better fertility. To improve the early fertility of the cow, there are a number of important factors that have to be taken into account.