scholarly journals Intergenerational conflicts may help explain parental absence effects on reproductive timing: a model of age at first birth in humans

PeerJ ◽  
2014 ◽  
Vol 2 ◽  
pp. e512 ◽  
Author(s):  
Cristina Moya ◽  
Rebecca Sear
Keyword(s):  
Age At First Birth ◽  
Reproductive Timing ◽  
First Birth ◽  
Parental Absence ◽  
Intergenerational Conflicts

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).

Antebellum Southern White Fertility: A Demographic and Economic Analysis

1980 ◽  
Vol 40 (2) ◽  
pp. 331-350 ◽  
Author(s):  
Richard H. Steckel
Keyword(s):  
Economic Analysis ◽  
Total Fertility Rate ◽  
Time Trend ◽  
Age At First Birth ◽  
Demographic Analysis ◽  
First Birth ◽  
Distribution Of Wealth ◽  
Socioeconomic Analysis ◽  
Family Limitation ◽  
Child Spacing

This paper investigates the decline and regional differential in antebellum southern white fertility using published census materials and the 1860 population schedules. Demographic analysis is conducted with a synthetic total fertility rate that has four components: age at first birth, age at last surviving birth, surviving-child spacing, and the proportion of women who eventually have surviving children. The socioeconomic analysis employs regressions and focuses on causes of the underlying changes in the components. Family limitation appears to have been unimportant in this population. The distribution of wealth was.probably an important factor shaping the time trend and regional differential in fertility.

Pregnancy and the Risk of Rheumatoid Arthritis in a Highly Predisposed North American Native Population

2012 ◽  
Vol 39 (12) ◽  
pp. 2253-2260 ◽  
Author(s):  
CHRISTINE A. PESCHKEN ◽  
DAVID B. ROBINSON ◽  
CAROL A. HITCHON ◽  
IRENE SMOLIK ◽  
DONNA HART ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
North American ◽  
Shared Epitope ◽  
Reproductive History ◽  
Early Age ◽  
Age At First Birth ◽  
Native Population ◽  
First Birth ◽  
Pregnancy Smoking ◽  
First Time

Objective.To examine reproductive history and rheumatoid arthritis (RA) risk in a highly predisposed population of North American Natives (NAN) with unique fertility characteristics.Methods.The effect of pregnancy on the risk of RA was examined by comparing women enrolled in 2 studies: a study of RA in NAN patients and their unaffected relatives; and NAN patients with RA and unrelated healthy NAN controls enrolled in a study of autoimmunity. All participants completed questionnaires detailing their reproductive history.Results.Patients with RA (n = 168) and controls (n = 400) were similar overall in age, education, shared epitope frequency, number of pregnancies, age at first pregnancy, smoking, and breastfeeding history. In multivariate analysis, for women who had ≥ 6 births the OR for developing RA was 0.43 (95% CI 0.21–0.87) compared with women who had 1–2 births (p = 0.046); for women who gave birth for the first time after age 20 the OR for developing RA was 0.33 (95% CI 0.16–0.66) compared with women whose first birth occurred at age ≤ 17 (p = 0.001). The highest risk of developing RA was in the first postpartum year (OR 3.8; 95% CI 1.45–9.93) compared with subsequent years (p = 0.004).Conclusion.In this unique population, greater parity significantly reduced the odds of RA; an early age at first birth increased the odds, and the postpartum period was confirmed as high risk for RA onset. The protective effect of repeated exposure to the ameliorating hormonal and immunological changes of pregnancy may counterbalance the effect of early exposure to the postpartum reversal of these changes.

Bounding Treatment Effects with Contaminated and Censored Data: Assessing the Impact of Early Childbearing on Children

2005 ◽  
Vol 5 (1) ◽  
Author(s):  
Charles H Mullin
Keyword(s):  
Censored Data ◽  
Treatment Effect ◽  
Instrumental Variable ◽  
Treatment Effects ◽  
Child Outcomes ◽  
Well Being ◽  
Teenage Mothers ◽  
Age At First Birth ◽  
First Birth ◽  
The Impact

AbstractEmpirical researchers commonly invoke instrumental variable (IV) assumptions to identify treatment effects. This paper considers what can be learned under two specific violations of those assumptions: contaminated and corrupted data. Either of these violations prevents point identification, but sharp bounds of the treatment effect remain feasible. In an applied example, random miscarriages are an IV for women’s age at first birth. However, the inability to separate random miscarriages from behaviorally induced miscarriages (those caused by smoking and drinking) results in a contaminated sample. Furthermore, censored child outcomes produce a corrupted sample. Despite these limitations, the bounds demonstrate that delaying the age at first birth for the current population of non-black teenage mothers reduces their first-born child’s well-being.

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