Age at first birth and subsequent fertility: The case of adolescent mothers in France and England and Wales

Scenarios of Delayed First Births and Associated Cohort Fertility Levels

Fertility rates among individuals in their 20s have fallen sharply across Europe over the past 50 years. The implications of delayed first births for fertility levels in modern family regimes remain little understood. Using microsimulation models of childbearing and partnership for the 1970-1979 birth cohorts in Italy, Great Britain, Sweden, and Norway, we implement fictive scenarios that reduce the risk of having a first child before age 30 and examine fertility recovery mechanisms for aggregate fertility indicators (the proportion of women with at least one, two, three, or four children; cohort completed fertility rate). Exposure to a first birth increases systematically in the ages following the simulated reduction in first-birth risks, leading to a structural recovery in childbearing that varies across countries according to their fertility and partnership regimes. Full recovery requires an increase in late first-birth risks, with greater increases in countries where late family formation is uncommon and average family sizes are larger: in scenarios where early fertility declines substantially (a linear decline from 50% at age 15 to 0% at age 30), first-birth risks above age 30 would have to increase by 54% in Great Britain, 40% in Norway and Sweden, and 20% in Italy to keep completed fertility constant.

Cross-sectional average length of life by parity: Country comparisons

This study aims to present an alternative measure of fertility-cross-sectional average length of life by parity (CALP)-which: (1) is a period fertility indicator using all available cohort information; (2) captures the dynamics of parity transitions; and (3) links information on fertility quantum and timing together as part of a single phenomenon. Using data from the Human Fertility Database, we calculate CALP for 12 countries in the Global North. Our results show that women spend the longest time at parity zero on average, and in countries where women spend comparatively longer time at parity zero, they spend fewer years at parities one and two. The analysis is extended by decomposing the differences in CALPs between Sweden and the United States, revealing age- and cohort-specific contributions to population-level differences in parity-specific fertility patterns. The decomposition illustrates how high teenage fertility in the United States dominates the differences between these two countries in the time spent at different parities.

An Integrated Machine Learning Scheme for Predicting Mammographic Anomalies in High-Risk Individuals Using Questionnaire-Based Predictors

This study aimed to investigate the important predictors related to predicting positive mammographic findings based on questionnaire-based demographic and obstetric/gynecological parameters using the proposed integrated machine learning (ML) scheme. The scheme combines the benefits of two well-known ML algorithms, namely, least absolute shrinkage and selection operator (Lasso) logistic regression and extreme gradient boosting (XGB), to provide adequate prediction for mammographic anomalies in high-risk individuals and the identification of significant risk factors. We collected questionnaire data on 18 breast-cancer-related risk factors from women who participated in a national mammographic screening program between January 2017 and December 2020 at a single tertiary referral hospital to correlate with their mammographic findings. The acquired data were retrospectively analyzed using the proposed integrated ML scheme. Based on the data from 21,107 valid questionnaires, the results showed that the Lasso logistic regression models with variable combinations generated by XGB could provide more effective prediction results. The top five significant predictors for positive mammography results were younger age, breast self-examination, older age at first childbirth, nulliparity, and history of mammography within 2 years, suggesting a need for timely mammographic screening for women with these risk factors.

Polarized adult fertility patterns following early parental death

Death of a parent during childhood has become rare in developed countries but remains an important life course event that may have consequences for family formation. This paper describes the link between parental death before age 18 and fertility outcomes in adulthood. Using the large national 2011 French Family Survey (INSEE-INED), we focus on the 1946-66 birth cohorts, for whom we observe entire fertility histories. The sample includes 11,854 respondents who have lost at least one parent before age 18. We find a strong polarization of fertility behaviours among orphaned males, more pronounced for those coming from a disadvantaged background. More often childless, particularly when parental death occurred in adolescence, some seem to retreat from parenthood. But orphaned men and women who do become parents seem to embrace family life, by beginning childbearing earlier and having more children, especially when the deceased parent is of the same sex.

Childbearing Biographies and Midlife Women's Health

OBJECTIVES

We introduce a "childbearing biography" approach to show how multiple childbearing characteristics cluster in ways significant for midlife health.

METHODS

We analyze the National Longitudinal Survey of Youth 1979 (NLSY79; N = 3992) using mixed-mode Latent Class Analysis with eight childbearing variables (e.g., age at first birth, parity, birth spacing, and mistimed births) to identify how childbearing biographies are associated with midlife health, adjusting for key covariates-including socioeconomic status (SES) and relationship history.

RESULTS

We identify six childbearing biographies: (1) early compressed, (2) staggered, (3) extended high parity, (4) later, (5) married planned, and (6) childfree. Childbearing biographies are strongly associated with physical health but not mental health, with differences primarily explained by SES.

DISCUSSION

Different childbearing biographies are related to physical health inequalities above what is demonstrated by the typical use of one or two childbearing measures, providing a new perspective into the growing health gap among aging midlife women.

Childbearing Biographies as a Method to Examine Diversity and Clustering of Childbearing Experiences: A Research Brief

Due to increasing heterogeneity in if, when, and under what conditions women have children, the timing, spacing, and other demographic aspects of childbearing have drastically changed in the US over the past century. Existing science tends to examine demographic aspects of childbearing separately, creating an incomplete understanding of how childbearing patterns are distributed at the population level. In this research brief, we develop the concept of childbearing biographies to emphasize that multiple childbearing characteristics cluster together. We analyze nationally representative US data from the 1979 National Longitudinal Survey of Youth (NLSY79; N=4,052). Using eight childbearing variables (e.g., age at first birth, number of children, whether unmarried at any birth), we use Mixed-Mode Latent Class Analysis (MM-LCA) and identify five classes, or childbearing biographies: (1) early compressed childbearing, (2) staggered childbearing, (3) extended high parity childbearing, (4) later childbearing, and (5) married planned childbearing. A childbearing biography approach highlights the increasingly heterogeneous contexts of parenthood today, showing how women with similar characteristics around one aspect of childbearing (e.g., early age at first birth) can also be highly divergent from each other when taking into consideration other childbearing characteristics. In showing this complexity, we highlight that a childbearing biography approach has the potential to shed new light on widening inequality among contemporary midlife women, with implications for aging and population health and well-being.

European countries with delayed childbearing are not those with lower fertility

At 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.