Alice Goisis

Social age deadlines for the childbearing of women and men

BACKGROUND This 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). METHODS This 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. RESULTS Social 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. CONCLUSIONS It 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.

Why are poorer children at higher risk of obesity and overweight? A UK cohort study

Background: There is limited evidence on which risk factors attenuate income inequalities in child overweight and obesity; whether and why these inequalities widen as children age. Method: Eleven thousand nine hundred and sixty five singletons had complete data at age 5 and 9384 at age 11 from the Millennium Cohort Study (UK). Overweight (age 5 : 15%; age 11 : 20%) and obesity (age 5 : 5%; age 11 : 6%) were defined using the International Obesity Taskforce body mass index cut-points. To measure socioeconomic inequalities, we used quintiles of family income and as risk factors, we considered markers of maternal health behaviours and of children’s physical activity, sedentary behaviours and diet. Binary and multinomial logistic regression models were used. Results: The unadjusted analyses revealed stark income inequalities in the risk of obesity at age 5 and 11. At age 5, children in the bottom income quintile had 2.0 (95% CI: 1.4–2.8) increased relative risk of being obese whilst at age 11 they had 3.0 (95% CI: 2.0–4.5) increased risk compared to children in the top income quintile. Similar income inequalities in the risk of overweight emerged by age 11. Physical activity and diet were particularly important in explaining inequalities. Income inequalities in obesity and overweight widened significantly between age 5 and 11 and a similar set of risk factors protected against upward and promoted downward movements across weight categories. Conclusions: To reduce income inequalities in overweight and obesity and their widening across childhood the results support the need of early interventions which take account of multiple risk factors.

Childbearing Postponement and Child Well-being: A Complex and Varied Relationship?

Over the past several decades, U.S. fertility has followed a trend toward the postponement of motherhood. The socioeconomic causes and consequences of this trend have been the focus of attention in the demographic literature. Given the socioeconomic advantages of those who postpone having children, some authors have argued that the disadvantage experienced by certain groups would be reduced if they postponed their births. The weathering hypothesis literature, by integrating a biosocial perspective, complicates this argument and posits that the costs and benefits of postponement may vary systematically across population subgroups. In particular, the literature on the weathering hypothesis argues that, as a consequence of their unique experiences of racism and disadvantage, African American women may experience a more rapid deterioration of their health which could offset or eventually reverse any socioeconomic benefit of postponement. But because very few African American women postpone motherhood, efforts to find compelling evidence to support the arguments of this perspective rely on a strategy of comparison that is problematic because a potentially selected group of older black mothers are used to represent the costs of postponement. This might explain why the weathering hypothesis has played a rather limited role in the way demographers conceptualize postponement and its consequences for well-being. In order to explore the potential utility of this perspective, we turn our attention to the UK context. Because first-birth fertility schedules are similar for black and white women, we can observe (rather than assume) whether the meaning and consequences of postponement vary across these population subgroups. The results, obtained using linked UK census and birth record data, reveal evidence consistent with the weathering hypothesis in the United Kingdom and lend support to the arguments that the demographic literature would benefit from integrating insights from this biosocial perspective.

How Are Children of Older Mothers Doing? Evidence from the United Kingdom.

Childbearing has been increasingly delayed in Western countries. As older mothers are likely to be advantaged over their younger counterparts, the demographic literature has tended to view this demographic trend as potentially beneficial for child well-being. Conversely, less attention has been given to medical studies showing that giving birth at advanced ages is associated with health risks for children. This article uses data from the Millennium Cohort Study (UK) and ordinary least squares and logistic regression models to compare cognitive and behavioral outcomes, and obesity at age 5 for first-born children by maternal age at first birth. On one hand, the findings suggest that giving birth to the first child at ages 30–39 compared to ages 23–29 is positively associated with children’s cognitive and behavioral outcomes and not associated with obesity. On the other hand, delaying the first birth to ages 40 and above is not associated with children’s cognitive and behavioral outcomes and is associated with increased risk of obesity. Although the results are unable to support the argument that this occurs because of the health risks associated with giving birth at advanced maternal ages, they suggest that there is a need to more closely investigate the potential trade-offs involved when births are delayed toward older maternal ages.

The reversing association between advanced maternal age and child cognitive ability: evidence from three UK birth cohorts

Abstract Background: Studies on advanced maternal age—defined here as age 35 or older—and children’s cognitive ability report mixed evidence. Previous studies have not analysed how the time period considered in existing studies influences the association. Methods: We analysed trends in the association between maternal age and cognitive ability using data from the 1958 National Child Development Study (n = 10 969), the 1970 British Cohort Study (n = 9362) and the 2000–2002 Millennium Cohort Study (n = 11 600). The dependent variable measures cognitive ability at age 10/11 years. Cognitive scores were standardised to a mean of zero and a standard deviation of one. Results: For the 1958–70 cohort studies, maternal ages 35 –39 were negatively associated with childrens cognitive ability compared with maternal ages 25–29 (1958 cohort β = −0.06 standard deviations (SD) 95% confidence interval (CI): −0.13, −0.00; 1970 cohort β = −0.12 SD 95% CI: −0.20, −0.03). By contrast, for the 2000–2002 cohort study maternal ages 35–39 were positively associated with cognitive ability (β = 0.16 SD 95% CI: 0.09, 0.23). For maternal ages 40+, the pattern was qualitatively similar. These cross-cohort differences were explained by the fact that in the earlier cohorts advanced maternal age was associated with high parity, whereas in the 2000–2002 cohort it was associated with socioeconomically advantaged family background. Conclusions: The association between advanced maternal age and children’s cognitive ability changed from negative in the 1958 and 1970 cohorts to positive in the 2000–2002 cohort because of changing parental characteristics. The time period considered can constitute an important factor in determining the association between maternal age and cognitive ability.

Decline in the negative association between low birth weight and cognitive ability

Significance Many studies have shown that children with a low birth weight (less than 2.5 kg) have worse cognitive ability than children with a normal birth weight. No existing study has analyzed whether, given the advances in neonatology and obstetric practice that have occurred over the past 50 years in developed contexts, the association between low birth weight and cognitive ability has changed over time. Using data from the 1958 National Child Development Study, the 1970 British Cohort Study, and the 2000–2002 Millennium Cohort Study, we show that the association between low birth weight and decreased cognitive ability has been more than halved between the 1958 and 1970 birth cohorts and the cohort born around the year 2001. Low birth weight predicts compromised cognitive ability. We used data from the 1958 National Child Development Study (NCDS), the 1970 British Cohort Study (BCS), and the 2000–2002 Millennium Cohort Study (MCS) to analyze how this association has changed over time. Birth weight was divided into two categories, <2,500 g (low) and 2,500–4,500 g (normal) and verbal cognitive ability was measured at the age of 10 or 11 y. A range of maternal and family characteristics collected at or soon after the time of birth were considered. Linear regression was used to analyze the association between birth weight and cognitive ability in a baseline model and in a model that adjusted for family characteristics. The standardized difference (SD) in cognitive scores between low-birth-weight and normal-birth-weight children was large in the NCDS [−0.37 SD, 95% confidence interval (CI): −0.46, −0.27] and in the BCS (−0.34, 95% CI: −0.43, −0.25) cohorts, and it was more than halved for children born in the MCS cohort (−0.14, 95% CI: −0.22, −0.06). The adjustment for family characteristics did not explain the cross-cohort differences. The results show that the association between low birth weight and decreased cognitive ability has declined between the 1950s and 1970s birth cohorts and the 2000--2002 birth cohort, despite a higher proportion of the low-birth-weight babies having a very low birth weight (<1,500 g) in the more recent birth cohort. Advancements in obstetric and neonatal care may have attenuated the negative consequences associated with being born small.

Advanced maternal age and the risk of low birth weight and preterm delivery: a within-family analysis using Finnish population registers

Abstract Advanced maternal age at birth is considered a major risk factor for birth outcomes. It is unclear to what extent this association is confounded by maternal characteristics. To test whether advanced maternal age at birth independently increases the risk of low birth weight (<2,500 g) and preterm birth (<37 weeks’ gestation), we compared between-family models (children born to different mothers at different ages) with within-family models (children born to the same mother at different ages). The latter procedure reduces confounding by unobserved parental characteristics that are shared by siblings. We used Finnish population registers, including 124,098 children born during 1987–2000. When compared with maternal ages 25–29 years in between-family models, maternal ages of 35–39 years and ≥40 years were associated with percentage increases of 1.1 points (95% confidence intervals: 0.8, 1.4) and 2.2 points (95% confidence intervals: 1.4, 2.9), respectively, in the probability of low birth weight. The associations are similar for the risk of preterm delivery. In within-family models, the relationship between advanced maternal age and low birth weight or preterm birth is statistically and substantively negligible. In Finland, advanced maternal age is not independently associated with the risk of low birth weight or preterm delivery among mothers who have had at least 2 live births.

Family Trajectories and Well-being of Children Born to Lone Mothers in the UK

We investigate how lone mothers’ heterogeneity in partnership trajectories is associated with children’s well-being. We use data from the Millennium Cohort Study, which follows a large sample of children born in the UK in 2000–2002. We divide children who were born to lone mothers into four groups based on their mothers’ partnership trajectories between birth and age seven, which cover more than 80% of these children’s family experiences. We then analyse how these trajectories are associated with markers of health, cognitive and socio-emotional outcomes measured at around age seven. We find that compared to the children that live continuously with lone mothers, children whose biological father stably joined the household have better cognitive and socio-emotional outcomes. In contrast, children in trajectories characterised by living with a stepfather or who experienced biological father joining in the family followed by biological parents’ dissolution had outcomes similar to children living continuously with lone mothers. The results underscore the importance of treating children born to lone mothers as a heterogeneous category.

Secular changes in the association between advanced maternal age and the risk of low birth weight: a cross-cohort comparison in the UK

Existing studies provide contradictory evidence concerning the association between child health and advanced maternal age. A potential explanation for the lack of consensus on this issue is changes over time in the costs and benefits of giving birth at an advanced age. This is the first study to investigate secular changes in the characteristics of older mothers and in the association between advanced maternal age and child health. We use data from four UK cohort studies, covering births from 1958 to 2001, and use low birth weight (LBW) as a marker for child health. We find that across successive birth cohorts, the negative association between advanced maternal age and LBW becomes progressively weaker; and that this pattern is partially explained by secular changes in the characteristics of older mothers. Our results suggest that associations between maternal age and child outcomes are tied to a specific population and point in time.

Paternal age and the risk of low birth weight and preterm delivery: a Finnish register-based study

Background Based on existing studies, there is no conclusive evidence as to whether and why paternal age matters for birth outcomes. Methods We used Finnish population registers on 106 652 children born 1987–2000. We first document the unadjusted association between paternal age and the risk of low birth weight (LBW; <2500 g) and preterm birth (<37 weeks’ gestation). Second, we investigate whether the unadjusted association is attenuated on adjustment for child’s, maternal and parental socioeconomic characteristics. Third, by adopting a within-family design which involves comparing children born to the same father at different ages, we additionally adjust for unobserved parental characteristics shared between siblings. Results The unadjusted results show that being born to a father aged 40+, as opposed to a father aged 30–34, is associated with an increased risk of LBW of 0.96% (95% CI 0.5% to 1.3%) and to a younger father (<25) with a 1% (95% CI 0.6% to 1.3%) increased risk. The increased risk at younger paternal ages is halved on adjustment for the child’s characteristics and fully attenuated on adjustment for child/parental characteristics. The increased risk at paternal ages 40+ is partially attenuated on adjustment for maternal characteristics (β=0.62%; 95% CI 0.13% to 1.1%). Adjustment for unobserved parental characteristics shared by siblings further attenuates the 40+ coefficient (β=0.4%; 95% CI −0.5% to −1.2%). Results for preterm delivery are similar. Conclusions The results underscore the importance of considering paternal age as a potential risk factor for adverse birth outcomes and of expanding research on its role and the mechanisms linking it to birth outcomes.