scholarly journals Variations in reproductive events across life: a pooled analysis of data from 505 147 women across 10 countries

2019 ◽  
Vol 34 (5) ◽  
pp. 881-893 ◽  
Author(s):  
Keyword(s):  
Age At Menarche ◽  
Age At First Birth ◽  
First Birth ◽  
Natural Menopause ◽  
Individual Level ◽  
Level Data ◽  
Education Levels ◽  
Reproductive Events ◽  
Racial Ethnic ◽  
Reproductive Indices

Abstract STUDY QUESTION How has the timing of women’s reproductive events (including ages at menarche, first birth, and natural menopause, and the number of children) changed across birth years, racial/ethnic groups and educational levels? SUMMARY ANSWER Women who were born in recent generations (1970–84 vs before 1930) or those who with higher education levels had menarche a year earlier, experienced a higher prevalence of nulliparity and had their first child at a later age. WHAT IS KNOWN ALREADY The timing of key reproductive events, such as menarche and menopause, is not only indicative of current health status but is linked to the risk of adverse hormone-related health outcomes in later life. Variations of reproductive indices across different birth years, race/ethnicity and socioeconomic positions have not been described comprehensively. STUDY DESIGN, SIZE, DURATION Individual-level data from 23 observational studies that contributed to the International Collaboration for a Life Course Approach to Reproductive Health and Chronic Disease Events (InterLACE) consortium were included. PARTICIPANTS/MATERIALS, SETTING, METHODS Altogether 505 147 women were included. Overall estimates for reproductive indices were obtained using a two-stage process: individual-level data from each study were analysed separately using generalised linear models. These estimates were then combined using random-effects meta-analyses. MAIN RESULTS AND THE ROLE OF CHANCE Mean ages were 12.9 years at menarche, 25.7 years at first birth, and 50.5 years at natural menopause, with significant between-study heterogeneity (I2 > 99%). A linear trend was observed across birth year for mean age at menarche, with women born from 1970 to 1984 having menarche one year earlier (12.6 years) than women born before 1930 (13.5 years) (P for trend = 0.0014). The prevalence of nulliparity rose progressively from 14% of women born from 1940–49 to 22% of women born 1970–84 (P = 0.003); similarly, the mean age at first birth rose from 24.8 to 27.3 years (P = 0.0016). Women with higher education levels had fewer children, later first birth, and later menopause than women with lower education levels. After adjusting for birth year and education level, substantial variation was present for all reproductive events across racial/ethnic/regional groups (all P values < 0.005). LIMITATIONS, REASONS FOR CAUTION Variations of study design, data collection methods, and sample selection across studies, as well as retrospectively reported age at menarche, age at first birth may cause some bias. WIDER IMPLICATIONS OF THE FINDINGS This global consortium study found robust evidence on variations in reproductive indices for women born in the 20th century that appear to have both biological and social origins. STUDY FUNDING/COMPETING INTEREST(S) InterLACE project is funded by the Australian National Health and Medical Research Council project grant (APP1027196). GDM is supported by the Australian National Health and Medical Research Council Principal Research Fellowship (APP1121844).

scholarly journals Age at Menarche, Age at Natural Menopause and Risk of Rheumatoid Arthritis – A Mendelian Randomization Study

2020 ◽  
Author(s):  
Jingjing Zhu ◽  
Zheng Niu ◽  
Lars Alfredsson ◽  
Lars Klareskog ◽  
Leonid Padyukov ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Mendelian Randomization ◽  
Reproductive Factors ◽  
European Ancestry ◽  
Age At Menarche ◽  
Age At First Birth ◽  
First Birth ◽  
Natural Menopause ◽  
Menarche Age ◽  
Mr Study

Abstract Background Hormonal reproductive factors have been suggested to play an important role in the etiology of rheumatoid arthritis (RA), an autoimmune inflammatory disorder affecting primarily women. We conducted a two-sample Mendelian randomization (MR) study examining three relevant exposures, age at menarche (AAM), age at natural menopause (ANM) and age at first birth (AFB), with the risk of RA.Methods We collected summary statistics from the hitherto largest GWAS conducted in AAM (N=329,345), ANM (N=69,360), AFB (N=251,151) and RA (Ncase=14,361 and Ncontrol=43,923), all of European ancestry. We constructed strong instruments using hundreds of exposure-associated genetic variants and estimated causal relationship through different MR approaches including an inverse-variance weighted method, an MR-Egger regression and a weighted-median method. We conducted a multivariable MR to control for pleiotropic effect acting in particular through obesity and socioeconomic status. We also performed important sensitivity analyses to verify model assumptions.Results We did not find any evidence in support for a causal association between genetically predicted reproductive factors and risk of RA (ORAAM=1.06 [0.98-1.15], ORANM=1.05 [0.98-1.11], ORAFB=0.85 [0.65-1.10]). Results remained consistent after removing palindromic SNPs (ORAAM=1.06 [0.97-1.15], ORANM=1.05 [0.98-1.13], ORAFB=0.81 [0.61-1.07]) or excluding SNPs associated with potential confounding traits (ORAAM=1.03 [0.94-1.12], ORANM=1.04 [0.95-1.14]). No outlying instrument was identified through the leave-one-out analysis.Conclusions Our MR study does not convincingly support a casual effect of reproductive factors, as reflected by age at menarche, age at menopause and age at first birth, on the development of RA. Despite the largely augmented set of instruments we used, these instruments only explained a modest proportion of phenotypic variance of exposures. Our knowledge regarding this topic is still insufficient and future studies with larger sample size should be designed to replicate or dispute our findings.

scholarly journals Age at menarche, age at natural menopause and risk of rheumatoid arthritis – a Mendelian randomization study

2021 ◽  
Author(s):  
Jingjing Zhu ◽  
Zheng Niu ◽  
Lars Alfredsson ◽  
Lars Klareskog ◽  
Leonid Padyukov ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Mendelian Randomization ◽  
Reproductive Factors ◽  
European Ancestry ◽  
Age At Menarche ◽  
Age At First Birth ◽  
First Birth ◽  
Natural Menopause ◽  
Menarche Age ◽  
Mr Study

Abstract Background Hormonal reproductive factors have been suggested to play an important role in the etiology of rheumatoid arthritis (RA), an autoimmune inflammatory disorder affecting primarily women. We conducted a two-sample Mendelian randomization (MR) study examining three relevant exposures, age at menarche (AAM), age at natural menopause (ANM) and age at first birth (AFB) with the risk of RA.Methods We collected summary statistics from the hitherto largest GWAS conducted in AAM (N=329,345), ANM (N=69,360), AFB (N=251,151) and RA (Ncase=14,361, Ncontrol=43,923), all of European ancestry. We constructed strong instruments using hundreds of exposure-associated genetic variants and estimated causal relationship through different MR approaches including an inverse-variance weighted method, an MR-Egger regression and a weighted-median method. We conducted a multivariable MR to control for pleiotropic effect acting in particular through obesity and socioeconomic status. We also performed important sensitivity analyses to verify model assumptions.Results We did not find any evidence in support for a causal association between genetically predicted reproductive factors and risk of RA (ORper-SD increment in AAM=1.06 [0.98-1.15]; ORper-SD increment in ANM=1.05 [0.98-1.11], OR per-SD increment in AFB=0.85 [0.65-1.10]). Results remained consistent after removing palindromic SNPs (ORper-SD increment in AAM=1.06 [0.97-1.15], ORper-SD increment in ANM=1.05 [0.98-1.13], ORper-SD increment in AFB=0.81 [0.61-1.07]) or excluding SNPs associated with potential confounding traits (ORper-SD increment in AAM=1.03 [0.94-1.12], ORper-SD increment in ANM=1.04 [0.95-1.14]). No outlying instrument was identified through the leave-one-out analysis.Conclusions Our MR study does not convincingly support a casual effect of reproductive factors, as reflected by age at menarche, age at menopause and age at first birth, on the development of RA. Despite the largely augmented set of instruments we used, these instruments only explained a modest proportion of phenotypic variance of exposures. Our knowledge regarding this topic is still insufficient and future studies with larger sample size should be designed to replicate or dispute our findings.

scholarly journals Age at menarche, age at natural menopause, and risk of rheumatoid arthritis — a Mendelian randomization study

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Jingjing Zhu ◽  
Zheng Niu ◽  
Lars Alfredsson ◽  
Lars Klareskog ◽  
Leonid Padyukov ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Mendelian Randomization ◽  
Reproductive Factors ◽  
European Ancestry ◽  
Age At Menarche ◽  
Age At First Birth ◽  
First Birth ◽  
Natural Menopause ◽  
Menarche Age ◽  
Mr Study

Abstract Background Hormonal reproductive factors have been suggested to play an important role in the etiology of rheumatoid arthritis (RA), an autoimmune inflammatory disorder affecting primarily women. We conducted a two-sample Mendelian randomization (MR) study examining three relevant exposures, age at menarche (AAM), age at natural menopause (ANM), and age at first birth (AFB) with the risk of RA. Methods We collected summary statistics from the hitherto largest GWAS conducted in AAM (N = 329,345), ANM (N = 69,360), AFB (N = 251,151), and RA (Ncase = 14,361, Ncontrol = 43,923), all of European ancestry. We constructed strong instruments using hundreds of exposure-associated genetic variants and estimated causal relationship through different MR approaches including an inverse-variance weighted method, an MR-Egger regression and a weighted median method. We conducted a multivariable MR to control for pleiotropic effect acting in particular through obesity and socioeconomic status. We also performed important sensitivity analyses to verify model assumptions. Results We did not find any evidence in support for a causal association between genetically predicted reproductive factors and risk of RA (ORper-SD increment in AAM = 1.06 [0.98–1.15]; ORper-SD increment in ANM = 1.05 [0.98–1.11], OR per-SD increment in AFB = 0.85 [0.65–1.10]). Results remained consistent after removing palindromic SNPs (ORper-SD increment in AAM = 1.06 [0.97–1.15], ORper-SD increment in ANM = 1.05 [0.98–1.13], ORper-SD increment in AFB = 0.81 [0.61–1.07]) or excluding SNPs associated with potential confounding traits (ORper-SD increment in AAM = 1.03 [0.94–1.12], ORper-SD increment in ANM = 1.04 [0.95–1.14]). No outlying instrument was identified through the leave-one-out analysis. Conclusions Our MR study does not convincingly support a casual effect of reproductive factors, as reflected by age at menarche, age at menopause, and age at first birth, on the development of RA. Despite the largely augmented set of instruments we used, these instruments only explained a modest proportion of phenotypic variance of exposures. Our knowledge regarding this topic is still insufficient and future studies with larger sample size should be designed to replicate or dispute our findings.

scholarly journals The relationships between women’s reproductive factors: a Mendelian randomization analysis

2021 ◽  
Author(s):  
Claire Prince ◽  
Gemma C Sharp ◽  
Laura D Howe ◽  
Abigail Fraser ◽  
Rebecca C Richmond
Keyword(s):  
Mendelian Randomization ◽  
Reproductive Factors ◽  
Sexual Partners ◽  
Age At Menarche ◽  
Age At First Birth ◽  
First Birth ◽  
Age At Menopause ◽  
Lifetime Number ◽  
Number Of Sexual Partners ◽  
Number Of Births

AbstractBackgroundWomen’s reproductive factors include their age at menarche and menopause, the age at which they start and stop having children, and the number of children they have. Studies that have linked these factors with disease risk have largely investigated individual reproductive factors and have not considered the genetic correlation and total interplay that may occur between them. This study aimed to investigate the nature of the relationships between eight female reproductive factors.MethodsWe used data from the UK Biobank and genetic consortia with data available for the following reproductive factors: age at menarche, age at menopause, age at first birth, age at last birth, number of births, being parous, age at first sex and lifetime number of sexual partners. Linkage disequilibrium score regression (LDSC) was performed to investigate the genetic correlation between reproductive factors. We then applied Mendelian randomization (MR) methods to estimate the causal relationships between these factors. Sensitivity analyses were used to investigate directionality of the effects, test for evidence of pleiotropy and account for sample overlap.ResultsLDSC indicated that most reproductive factors are genetically correlated (rg range: |0.06 – 0.94|), though there was little evidence for genetic correlations between lifetime number of sexual partners and age at last birth, number of births and ever being parous (rg < 0.01). MR revealed potential causal relationships between many reproductive factors, including later age at menarche (1 SD increase) leading to a later age at first sexual intercourse (Beta (B)=0.09 SD, 95% confidence intervals (CI)=0.06,0.11), age at first birth (B=0.07 SD, CI=0.04,0.10), age at last birth (B=0.06 SD, CI=0.04,0.09) and age at menopause (B=0.06 SD, CI=0.03,0.10). Later age at first birth was found to lead to a later age at menopause (B=0.21 SD, CI=0.13,0.29), age at last birth (B=0.72 SD, CI=0.67,0.77) and a lower number of births (B=-0.38 SD, CI=-0.44,-0.32).ConclusionThis study presents evidence that women’s reproductive factors are genetically correlated and causally related. Future studies examining the health sequelae of reproductive factors should consider a woman’s entire reproductive history, including the causal interplay between reproductive factors.

scholarly journals European countries with delayed childbearing are not those with lower fertility

Genus ◽  
2021 ◽  
Vol 77 (1) ◽  
Author(s):  
Éva Beaujouan ◽  
Laurent Toulemon
Keyword(s):  
Context Effects ◽  
Negative Relationship ◽  
Age At First Birth ◽  
First Birth ◽  
Individual Level ◽  
Number Of Children ◽  
Country Level ◽  
Strong Negative Relationship ◽  
Lower Fertility ◽  
The Individual

AbstractAt the individual level, a very strong negative relationship is observed between age at first birth and total number of children. However, at the country level, it is possible that no relationship exists between factors that reduce fertility at younger ages and stimulate it at older ages. Hence, across countries, the size of the decline in youth fertility is potentially unrelated to the size of the increase in fertility at older ages or the decline in total fertility. We study the fertility of women and their age at childbirth, with particular attention to their evolution over the last 40 years in countries across Europe. Comparing these countries, the increase in births after age 30 has occurred relatively independently of the decline at younger ages according to both period and cohort, and we find no positive relationship between the delay of first birth and decline in total fertility. On the contrary, an inverse relationship evidently exists at the country level, as longer delays generally correspond to smaller declines in total fertility. Context effects largely dominate individual constraints and play an important role in the occurrence of later births.

A PROSPECTIVE STUDY OF AGE AT MENARCHE, PARITY, AGE AT FIRST BIRTH, AND CORONARY HEART DISEASE IN WOMEN

1987 ◽  
Vol 126 (5) ◽  
pp. 861-870 ◽  
Author(s):  
GRAHAM A. COLDITZ ◽  
WALTER C. WILLETT ◽  
MEIR J. STAMPFER ◽  
BERNARD ROSNER ◽  
FRANK E. SPEIZER ◽  
...  
Keyword(s):  
Coronary Heart Disease ◽  
Heart Disease ◽  
Prospective Study ◽  
Age At Menarche ◽  
Age At First Birth ◽  
First Birth ◽  
A Prospective Study

Electoral reforms and the representativeness of turnout

2020 ◽  
pp. 1-15
Author(s):  
Michael M. Bechtel ◽  
Lukas Schmid
Keyword(s):  
Political Participation ◽  
Policy Instruments ◽  
Aggregate Level ◽  
Individual Level ◽  
Level Data ◽  
Medium Education ◽  
Wide Range ◽  
Education Levels ◽  
Electoral Reforms ◽  
The Impact

Abstract Voters tend to be richer, more conservative, and more educated than non-voters. While many electoral reforms promise to increase political participation, these policy instruments may have multidimensional and differential effects that can increase or decrease the representativeness of turnout. We develop an approach that allows us to estimate these effects and assess the impact of postal voting on representational inequality in Swiss referendums using individual-level ( $N = 79\comma\; 000$ ) and aggregate-level data from 1981 to 2009. We find that postal voting mobilizes equally across a wide range of political and sociodemographic groups but more strongly activates high earners, those with medium education levels, and less politically interested individuals. Yet, those who vote are not less politically knowledgeable and the effects on the composition of turnout remain limited. Our results inform research on the consequences of electoral reforms meant to increase political participation in large electorates.

scholarly journals Nonparametric double additive cure survival models: An application to the estimation of the non-linear effect of age at first parenthood on fertility progression

2018 ◽  
Vol 19 (3) ◽  
pp. 248-275 ◽  
Author(s):  
Vincent Bremhorst ◽  
Michaela Kreyenfeld ◽  
Philippe Lambert
Keyword(s):  
Probability Model ◽  
Additive Models ◽  
Survival Models ◽  
Age At First Birth ◽  
First Birth ◽  
Second Child ◽  
Linear Effect ◽  
Education Levels ◽  
Mother’S Age ◽  
Effect Of Age

This article introduces double additive models to describe the effect of continuous covariates in cure survival models, thereby relaxing the traditional linearity assumption in the two regression parts. This class of models extends the classical event history models when an unknown proportion of the population under study will never experience the event of interest. They are used on data from the German Socio-Economic Panel (GSOEP) to examine how age at first birth relates to the timing and quantum of fertility for given education levels of the respondents. It is shown that the conditional probability of having further children decreases with the mother's age at first birth. While the effect of age at first birth in the third birth's probability model is fairly linear, this is not the case for the second child with an accelerating decline detected for women that had their first kid beyond age 30.

scholarly journals Faster Transition to the Second Child in late 20th Century Finland: A Study of Birth Intervals

2014 ◽  
Vol 49 ◽  
pp. 73-86 ◽  
Author(s):  
Venla Berg ◽  
Anna Rotkirch
Keyword(s):  
Educational Level ◽  
Age At First Birth ◽  
Interbirth Interval ◽  
First Birth ◽  
Birth Intervals ◽  
Late 20Th Century ◽  
Second Child ◽  
Individual Level ◽  
Health And Wellbeing ◽  
Effect Of Age

Birth intervals are known to influence child and parental health and wellbeing, yet studies on the recent development of birth intervals in contemporary developed societies are scarce. We used individual-level representative register data from Finland (N=26,120; 54% women) to study the first interbirth interval of singleton births in cohorts born in 1955, 1960, 1965, 1970, and 1975. In women, the average interbirth interval has shortened by 7.8 months and in men by 6.2 months between the cohorts of 1955 and 1975. A higher age at first birth was associated with shorter birth intervals (in women, b = -1.68, p<.001; in men, b = -1.77, p<.001 months per year). Educational level moderated the effect of age at first on the first birth interval in both sexes. Due to rising ages at first birth in developed societies and the manifold ramifications of shorter birth intervals, this topic deserves more scholarly attention and studies from other countries.

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