Childbearing postponement and child well-being: a complex and varied relationship?

The effect of China's birth policy changes on birth defects-A large hospital-based cross-sectional study

A retrospective analysis of birth data hospital-based obtained from 14 monitoring areas in the Huaihe River Basin from 2009 to 2019 was conducted. Trend in the total prevalence of birth defects (BDs) and subgroups were analyzed using the Joinpoint Regression model. The incidence of BDs increased gradually from 118.87 per 10,000 in 2009 to 241.18 per 10,000 in 2019 (AAPC = 5.91, P < 0.001). Congenital heart diseases were the most common subtype of BDs. The proportion of maternal age younger than 25 decreased but the age 25-40 years increased significantly (AAPC<20=-5.58; AAPC20-24=-6.38; AAPC25-29 = 5.15; AAPC30-35 = 7.07; AAPC35-40 = 8.27; All P < 0.05). Compared with the one-child policy period, the risk of BDs was greater for groups among maternal age younger than 40 years during the partial and universal two-child policy period (P < 0.001). The incidence of BDs and the proportion of women with advanced maternal age in Huaihe River Basin is increasing. There was an interaction between changes in birth policy and the mother's age on the risk of BDs.

Forced Migration and the Childbearing of Women and Men: A Disruption of the Tempo and Quantum of Fertility?

It is well known that migrant fertility is associated with age at migration, but little is known about this relationship for forced migrants. We study an example of displacement in which the entire population of Finnish Karelia was forced to move elsewhere in Finland in the 1940s. This displacement was unique because of its size and scale, because we have data on almost the whole population of both men and women who moved, and because of the similarity between origin and destination. These aspects enable us to investigate the disruptive impact of forced migration, net of other factors such as adaptation and selection. For all ages at migration from one to 20, female forced migrants had lower levels of completed fertility than similar women born in present-day Finland, which suggests a permanent impact of migration. However, women born in the same year as the initial forced migration showed no difference, which may indicate the presence of a counterbalancing fertility-increasing effect, as observed elsewhere for people born during a humanitarian crisis. There is less evidence of an impact for men, which suggests a gendered impact of forced migration-and its timing-on fertility. Results are similar after controlling for social and spatial mobility, indicating that there may be no major trade-off between reproduction and these forms of mobility.

Changes in adverse pregnancy outcomes in women with advanced maternal age (AMA) after the enactment of China's universal two-child policy

The universal two-child policy (TCP; 2016) in China has affected many aspects of maternal-neonatal health. A tertiary hospital-based retrospective study (2011–2019) was used to find the association of these policy changes with maternal age and pregnancy outcomes in women with AMA (≥ 35 years) in the Hubei Province, China. The proportion of neonatal births to women with AMA increased by 68.8% from 12.5% in the one-child policy (OCP) period to 21.1% in the universal TCP period [aOR 1.76 (95% CI: 1.60, 1.93)]. In the univariate analysis, the proportion of preterm births (29.4% to 24.1%), low birth weight (LBW) (20.9% to 15.9%), and hypertensive disorders of pregnancy (HDP) (11.5% to 9.2%) significantly (p < 0.05) decreased in women with AMA from the OCP period to universal TCP period. However, the proportion of intrauterine growth restriction (IUGR) (0.2% to 0.7%) and gestational diabetes mellitus (GDM) (1.7% to 15.6%) was significantly (p < 0.05) increased over the policy changes. After adjusting for confounding factors, only the risk of GDM increased [aOR 10.91 (95% CI: 6.05, 19.67)] in women with AMA from the OCP period to the universal TCP period. In conclusion, the risk of GDM increased in women with AMA from the OCP period to the universal TCP period.

Different maternal age patterns of preterm birth: Interplay of race/ethnicity, chronic stress, and marital status

The aim of this study was to examine whether the preterm birth (PTB) risks according to maternal age is altered by a woman's marital status and chronic stress among non-Hispanic (N-H) White, N-H Black, Hispanic, and Asian women. This researcher analyzed the Pregnancy Risk Assessment Monitoring System data for New York City and Washington State linked with the birth certificates for 2004-2007. The sample included 6344 singleton live births without birth defects to women aged 18 years or older identified as N-H White, N-H Black, Hispanic, or Asian. The outcome was PTB. Maternal age-specific PTB rates were calculated according to race/ethnicity, marital status, and chronic stress. Linear trends of PTB rates with maternal age were evaluated by the Mantel-Haenszel χ² test. Marriage had a protective effect against PTB at advancing maternal age across racial/ethnic groups. The health benefit of marriage was strong, particularly among the married N-H Black and Asian women, manifested as a maternal age-related decrease in the PTB rate (reverse-weathering). In contrast, women not married showed a maternal age-related increase in the PTB rate (weathering) across the racial/ethnic groups. Under higher chronic stress, married women generally experienced less weathering about PTB. These patterns were observed with noticeable racial/ethnic variations. Acknowledging the different dynamics among maternal age, marital status, and chronic stress by race/ethnicity could help shed light on the psychosocial mechanisms underlying the racial/ethnic inequalities in PTB in the United States. To that end, future studies should use more nuanced measurements of paternal support and chronic stress.

Demography's theory and approach: (How) has the view from the margins changed?

Around the time that Population Studies celebrated its 50th anniversary in 1996, Susan Greenhalgh published 'An intellectual, institutional, and political history of twentieth-century demography'. Her contribution described a discipline that, when viewed from its margins, prompted scholars in other disciplines to ask the following questions: 'Why is the field still wedded to many of the assumptions of mid-century modernization theory and why are there no critical … perspectives in the discipline?' (Greenhalgh 1996, p. 27). Those questions still arise today. Similarly, Greenhalgh's observation that 'neither the global political economies of the 1970s, nor the postmodernisms and postcolonialities of the 1980s and 1990s, nor the feminisms of any decade have had much perceptible impact on the field' (pp. 27-8), remains a fairly accurate depiction of research published in Population Studies and other demography journals. In this contribution, focusing predominantly on feminist research and insights, I discuss how little has changed since 1996 and explain why the continued lack of engagement concerns me. Demographers still often fail to appreciate the impossibility of atheoretical 'just descriptive' research. Our methods carry assumptions and so rely on (often) implicit theoretical frameworks. Not making frameworks explicit does not mean they do not exert an important influence. I end by proposing that the training of research students should be part of a strategy to effect change.

What's so troubling about 'voluntary' family planning anyway? A feminist perspective

Voluntary family planning is a key mainstay of demographic work and population policies. The 1994 International Conference on Population and Development (ICPD) signalled a decisive shift away from fertility reduction and target-setting to an emphasis on voluntary family planning as intrinsic to reproductive health and women's empowerment. Yet, criticisms of voluntary family planning programmes persist, interrogating how 'voluntariness' is understood and wielded or questioning the instrumentalization of women's fertilities in the service of economic and developmental goals. In this paper, I reflect on these debates with the aim of troubling the notion of voluntary family planning as an unambiguous good that enables equitable empowerment and development for all. Drawing on literature from cognate disciplines, I highlight how voluntariness is linked to social and structural conditions, and I challenge the instrumentalization of voluntary family planning as a 'common agenda' to solve 'development' problems. Engaging with this work can contribute to key concepts (e.g. 'voluntary') and measurements (e.g. autonomy), strengthening the collective commitment to achieving the ICPD and contributing to reproductive empowerment and autonomy. Through this intervention, I aim to help demographers see why some critics call for a reconsideration of voluntary family planning and encourage a decoupling of interventions from fertility reduction aims, instead centring human rights, autonomy, and reproductive empowerment.

How do reproduction, parenting, and health cluster together? Exploring diverging destinies, life histories and weathering in two UK cohort studies

Life history theory researchers often assume reproductive, parenting and health behaviours pattern across a fast-slow continuum, with 'fast' life histories (typified by short lifespans, early maturation and investing in quantity over quality of children) favoured in poor quality environments and/or when resources are scarce. Some researchers further reduce this down to a simplistic 'fast' versus 'slow' dichotomy. Some of these ideas, with different theoretical motivations, are echoed in the 'diverging destinies' and 'weathering' frameworks developed in the social sciences. Whether clustering of reproductive, parenting and health traits exists has rarely been empirically tested, however. Using latent class analysis on data on mothers from the UK's Millennium Cohort (MCS) and Born in Bradford (BiB) studies, we explored whether reproduction and parenting traits clustered into 'diverging destinies', whether 'weathering' effects tied together health and reproduction, and whether all three domains were combined into either 'fast' vs 'slow' life histories, or into three groups more indicative of a fast-slow continuum. We leveraged ethnic diversity in these samples to examine four groups of mothers separately: 1. MCS White British/Irish (n = 15,423); 2. MCS Pakistani-origin (n = 923); 3. BiB White British (n = 3937); 4. BiB Pakistani-origin (n = 4351), and explored whether faster 'weathering' was evident amongst Pakistani-origin mothers. Both two and three class models emerged as potential descriptions of latent subgroups, potentially providing support for fast and slow life histories or a continuum of traits. However, response profiles provided only limited support for theoretical predictions of which traits should cluster together, with inconsistent and restricted clustering of traits both within and between the domains of reproduction, parenting, and health. In addition, trait clustering was more pronounced amongst White mothers and we found no clear evidence supporting faster 'weathering' amongst Pakistani-origin mothers; the observed clustering instead suggested that cultural constraints may influence linkages between traits. Our results therefore provide some limited support for models which suggest certain traits cluster together in predictable ways, but it is also clear that theoretical frameworks should not emphasise very rigid clustering of large numbers of traits and should allow for contextual influences on clustering.

The Fertility of Immigrants From Low-Fertility Settings: Adaptation in the Quantum and Tempo of Childbearing?

Immigrant women who have lived longer in a destination often have relatively low levels of fertility, which is sometimes taken as evidence of the adaptation of behavior. This evidence is almost exclusively based on studies of immigrants from high-fertility settings, while the fertility of immigrants from low-fertility settings has been largely overlooked. Research has also rarely studied the fertility of immigrants who migrated as children, despite the methodological advantages of applying such an approach. This study focuses on women who grew up in Sweden with a migration background from low-fertility origins. We expect that Sweden's welfare regime makes it easier for women to combine childbearing and working life, regardless of migration background, thereby facilitating an adaptation of fertility behavior toward that prevailing in Sweden. We find evidence of adaptation in terms of birth timing for at least half of the country-origin groups that we study, but very little evidence of adaptation in terms of completed fertility. Further, we find that, in comparison with ancestral Swedes, completed fertility differentials are larger for second-generation individuals than for immigrants who arrived during childhood. This is evidence against the notion of "straight-line" adaptation for immigrants and the children of immigrants who are born in Sweden.

Neurodevelopmental outcomes of preterm infants conceived by assisted reproductive technology

BACKGROUND

There have been concerns about the development of children conceived through assisted reproductive technology. Despite multiple studies investigating the outcomes of assisted conception, data focusing specifically on the neurodevelopmental outcomes of infants conceived through assisted reproductive technology and born preterm are limited.

OBJECTIVE

This study aimed to evaluate and compare the neurodevelopmental outcomes of preterm infants born at <29 weeks' gestation at 18 to 24 months' corrected age who were conceived through assisted reproductive technology and those who were conceived naturally.

STUDY DESIGN

This retrospective cohort study included inborn, nonanomalous infants, born at <29 weeks' gestation between January 1, 2010, and December 31, 2016, who had a neurodevelopmental assessment at 18 to 24 months' corrected age at any of the 10 Canadian Neonatal Follow-Up Network clinics. The primary outcome was neurodevelopmental impairment at 18 to 24 months, defined as the presence of any of the following: cerebral palsy; Bayley-III cognitive, motor, or language composite score of <85; sensorineural or mixed hearing loss; and unilateral or bilateral visual impairment. Secondary outcomes included mortality, composite of mortality or neurodevelopmental impairment, significant neurodevelopmental impairment, and each component of the primary outcome. We compared outcomes between infants conceived through assisted reproductive technology and those conceived naturally, using bivariate and multivariable analyses after adjustment.

RESULTS

Of the 4863 eligible neonates, 651 (13.4%) were conceived using assisted reproductive technology. Maternal age; education level; and rates of diabetes mellitus, receipt of antenatal corticosteroids, and cesarean delivery were higher in the assisted reproduction group than the natural conception group. Neonatal morbidity and death rates were similar except for intraventricular hemorrhage, which was lower in the assisted reproduction group (33% [181 of 546] vs 39% [1284 of 3318]; P=.01). Of the 4176 surviving infants, 3386 (81%) had a follow-up outcome at 18 to 24 months' corrected age. Multivariable logistic regression adjusting for gestational age, antenatal steroids, sex, small for gestational age, multiple gestations, mode of delivery, maternal age, maternal education, pregnancy-induced hypertension, maternal diabetes mellitus, and smoking showed that infants conceived through assisted reproduction was associated with lower odds of neurodevelopmental impairment (adjusted odds ratio, 0.67; 95% confidence interval, 0.52-0.86) and the composite of death or neurodevelopmental impairment (adjusted odds ratio, 0.67; 95% confidence interval, 0.54-0.84). Conception through assisted reproductive technology was associated with decreased odds of a Bayley-III composite cognitive score of <85 (adjusted odds ratio, 0.68; 95% confidence interval, 0.48-0.99) and composite language score of <85 (adjusted odds ratio, 0.67; 95% confidence interval, 0.50-0.88).

CONCLUSION

Compared with natural conception, assisted conception was associated with lower odds of adverse neurodevelopmental outcomes, especially cognitive and language outcomes, at 18 to 24 months' corrected age among preterm infants born at <29 weeks' gestation. Long-term follow-up studies are required to assess the risks of learning disabilities and development of complex visual-spatial and processing skills in these children as they reach school age.

The cognitive development from childhood to adolescence of low birthweight children born after medically assisted reproduction-a UK longitudinal cohort study

Background

Previous research has documented that children conceived through medically assisted reproduction (MAR) are at increased risk of poor birth outcomes, such as low birthweight (LBW), which are risk factors for stunted longer-term cognitive development. However, parents who undergo MAR to conceive have, on average, advantaged socioeconomic backgrounds which could compensate for the negative effects of being born LBW. Previous studies have not analysed whether the negative effects of LBW are attenuated among MAR conceived children.

Methods

We draw on the UK Millennium Cohort Study (sweeps 1–6) which contains a sub-sample of (N = 396) MAR-conceived children. The dependent variable measures cognitive ability at around ages 3, 5, 7, 11 and 14. We examine the cognitive development of four groups of children: MAR-conceived low birthweight (MAR LBW); MAR-conceived non-low birthweight (MAR NLBW); naturally conceived low birthweight (NC LBW); naturally conceived non-low birthweight (NC NLBW). We estimate the two following linear regression models for each sweep: (i) a baseline model to examine the unadjusted association between cognitive development and low birthweight by mode of conception; and (ii) a model adjusted by socio-demographic family characteristics.

Results

In baseline models, MAR LBW children [age 3: β  =  0.021, 95% confidence interval (CI): -0.198, 0.241; age 5: β  =  0.21, 95% CI: 0.009, 0.418; age 7: β  =  0.163, 95% CI: -0.148, 0.474; age 11: β  =  0.003, 95% CI: -0.318, 0.325; age 14: β  =  0.156, 95% CI: -0.205, 0.517], on average perform similarly in cognitive ability relative to NC NLBW at all ages, and display higher cognitive scores than NC LBW children until age 7. When we account for family characteristics, differences are largely attenuated and become close to zero at age 14.

Conclusions

Despite the higher incidence of LBW among MAR compared with NC children, they do not seem to experience any disadvantage in their cognitive development compared with naturally conceived children. This finding is likely explained by the fact that, on average, MAR children are born to socioeconomically advantaged parents.

Parental age at childbirth and children’s educational outcomes: evidence from upper-secondary schools in Italy

In the last decades, Western societies have been involved in huge demographic changes, amongst which one of the most important has been the increasing postponement of the transition to parenthood. This paper aims at analysing the consequences of later motherhood and fatherhood on children’s participation in upper-secondary schools in Italy, considering both the vertical and horizontal dimensions of education. It also aims at highlighting the role of father-mother age difference and heterogeneity in the effects by parental SES and birth order. Using Italian labour force survey data (2005-2014), results show that late parenthood is positively associated with educational attainment, whereas teenage and early parenthood negatively affect children’s educational outcomes, net of detailed information on parental SES. Age at parenthood affects the educational achievement mostly for children of low- and middle-educated parents, who are more penalized by early childbearing and more favoured by late parenthood than the offspring of the tertiary educated. Moreover, only children are less affected by age at parenthood, especially in comparison with later-born children. Finally, children’s educational outcomes are worse when the mother is older than the father, independently from the educational outcome considered, whereas they are better in case of parental age homogamy or when the father is slightly older than the mother.

Changes in maternal age and prevalence of congenital anomalies during the enactment of China's universal two-child policy (2013-2017) in Zhejiang Province, China: An observational study

BACKGROUND

China implemented a partial two-child policy (2013) followed by a universal two-child policy (2015), replacing the former one-child policy mandated by the government. The changes affect many aspects of China's population as well as maternal and infant health, but their potential impact on birth defects (BDs) remains unknown. In this study, we investigated the associations of these policy changes with BDs in Zhejiang Province, China.

METHODS AND FINDINGS

We used data from the BD surveillance system in Zhejiang Province, China, which covers 90 hospitals in 30 urban districts and rural counties, capturing one-third of the total births in this province. To fully consider the time interval between conception and delivery, we defined the one-child policy period as data from 2013 (births from October 2012 to September 2013), the partial two-child policy period as data from 2015 (births from October 2014 to September 2015), and the universal two-child policy period as data from 2017 (births from October 2016 to September 2017). Data from 2009 and 2011 were also used to show the changes in the proportion of births to women with advanced maternal age (35 years and older) prior to the policy changes. Main outcome measures were changes in the proportion of mothers with advanced maternal age, prevalence of BDs, rankings of BD subtypes by prevalence, prenatal diagnosis rate, and live birth rate of BDs over time. A total of 1,260,684 births (including live births, early fetal losses, stillbirths, and early neonatal deaths) were included in the analyses. Of these, 644,973 (51.16%) births were to women from urban areas, and 615,711 (48.84%) births were to women from rural areas. In total, 135,543 (10.75%) births were to women with advanced maternal age. The proportion increased by 85.68%, from 8.52% in 2013 to 15.82% in 2017. However, it had remained stable prior to policy changes. Overall, 23,095 BDs were identified over the policy changes (2013-2017). The prevalence of BDs during 2013, 2015, and 2017 was 245.95, 264.86, and 304.36 per 10,000 births, respectively. Trisomy 21 and other chromosomal defects increased in both risk and ranking from 2013 to 2017 (crude odds ratio [95% confidence interval] 2.13 [1.75-2.60], from ranking 10th to 5th, and 3.63 [2.84-4.69], from ranking 16th to 6th, respectively). The prenatal diagnosis rate increased by 3.63 (2.2-5.1) percentage points (P < 0.001), from 31.10% to 34.72%, and identification of BDs occurred 1.88 (1.81-1.95) weeks earlier (P < 0.001). The live birth rate for infants with BDs born before 28 gestational weeks increased from 1.29% to 11.45%. The major limitations of this observational study include an inability to establish causality and the possible existence of unknown confounding factors, some of which could contribute to BDs.

CONCLUSIONS

In this study, we observed significant increases in maternal age and the prevalence of total and age-related anomalies following China's new two-child policy. Increases in live birth rate for infants with BDs born before 28 gestational weeks suggest that healthcare for very preterm births with BDs may be warranted in the future, as well as updating the definition of perinatal period.

Mind the gap: The health advantages that accompany parental marriage vary by maternal nativity

Using data from the UK Millennium Cohort Study (MCS), we examine whether and how the health benefits of having two biological parents in a continuous marital relationship vary by maternal nativity and ethnicity, comparing UK-born White mothers with: (1) White mothers born in wealthy countries; (2) ethnic minority mothers from South Asia; and (3) ethnic minority mothers born in Africa. Making novel use of classification and regression tree (CART) methods, we examine whether marital status is a uniform marker of economic advantage or better health-related behaviours across the four maternal nativity and ethnic groups. The findings, which indicate that the health-related advantages associated with parental marriage are not uniform across the four nativity and ethnic groups, have implications for future research on family gaps in well-being and the socio-economic determinants of health.

Fertility histories and chronic conditions later in life in Europe

Understanding the association between fertility histories and health later in life is necessary in the context of ageing societies. Past literature has generally found a U-shaped relationship between parity, age at first birth, and several health-related outcomes. However, these findings differed to some extent depending on the country under analysis and on the measures of health considered. As such, using wave 3 (2008-2009) and 5 (2013) of the Survey of Health, Ageing and Retirement in Europe (SHARE), this work aimed to answer the question: "Are fertility histories associated with the presence of chronic conditions later in life in Europe?" The analysis included 11 European countries and compared results using two different measures of chronic conditions: self-reported chronic or long-term illness and chronic diseases diagnosed by a doctor. Results showed that age at first birth is more relevant than parity for health outcomes at older ages. Moreover, in socio-democratic and continental countries, the association between fertility and chronic conditions-in particular between age at first birth and long-term illnesses-is statistically significant among women, but not among men. Finally, the association between fertility history and health was similar when using self-reported measures and chronic diseases diagnosed by a doctor.

When richer doesn't mean thinner: Ethnicity, socioeconomic position, and the risk of child obesity in the United Kingdom

BACKGROUND

A range of studies report a robust association between family socioeconomic position and the prevalence of child overweight/obesity. On average, children from poorer backgrounds are more likely to be overweight/obese than children from more advantaged families. However, a small number of US studies have shown that, for ethnic minority children, the association is either nonexistent or reversed.

OBJECTIVE

We test if the link between socioeconomic position and child overweight/obesity at age 7 is heterogeneous in the United Kingdom where rates of obesity are particularly high for some groups of ethnic minority children.

METHODS

We use nationally representative data from the UK Millennium Cohort Study as well as descriptive analyses and logistic regression models.

RESULTS

Poorer White children are at higher risk of overweight/obesity than higher income White children. However, socioeconomic disparities are reversed for Black African/Caribbean children and nonexistent for children of Indian and Pakistani/Bangladeshi origin. Moreover, the health behaviours that explain socioeconomic disparities in child overweight/obesity for the White group appear to be irrelevant in explaining differences by socioeconomic position for the Black Caribbean and African groups.

CONCLUSIONS

We should be careful in assuming that higher socioeconomic position is protective against child overweight/obesity for all groups of the population.

CONTRIBUTION

This study shows for the first time important variation by ethnicity in the link between socioeconomic position and child overweight/obesity - and in the underlying mechanisms linking them - in the United Kingdom.

The weathering hypothesis as an explanation for racial disparities in health: a systematic review

PURPOSE

The weathering hypothesis states that chronic exposure to social and economic disadvantage leads to accelerated decline in physical health outcomes and could partially explain racial disparities in a wide array of health conditions. This systematic review summarizes the literature empirically testing the weathering hypothesis and assesses the quality of the evidence regarding weathering as a determinant of racial disparities in health.

METHODS

Databases (Web of Science, Ovid MEDLINE, PubMed, and Embase) were searched for studies published in English up to July 1, 2017. Studies that tested the weathering hypothesis for any physical health outcome and included at least one socially or economically disadvantaged group (e.g., Blacks) for whom the weathering hypothesis applies were assessed for eligibility. Threats to validity were assessed using the Quality in Prognostic Studies tool.

RESULTS

The 41 included studies were rated as having overall good methodological quality. Most studies found evidence in support of the weathering hypothesis, although the magnitude of support varied by the health outcome and population studied.

CONCLUSIONS

Future evaluations of the weathering hypothesis should include an examination of additional health outcomes and interrogate mechanisms that could link weathering to poor health.

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

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 children's 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.

Cognitive development in children up to age 11 years born after ART-a longitudinal cohort study

STUDY QUESTION

How does the cognitive development of children conceived after ART (IVF and ICSI) - measured as cognitive skills at age 3, 5, 7 and 11 years - differ over time from those born after natural conception (NC)?

SUMMARY ANSWER

Improved measures of cognitive development up to age 5 years were recorded in children conceived with ART compared to NC, which attenuates by 11 years, with ART children still scoring slightly better than NC children.

WHAT IS KNOWN ALREADY

Results on the cognitive outcomes of children conceived after ART have been highly contradictory. Some have shown that ART children have an impaired behavioural, socio-emotional and cognitive development and higher risk of mental disorders. Others have reported no increased risk or difference. Cognitive development has not been previously examined using latent growth curve models from ages 3 to 11 years, also including appropriate attention to confounding parental characteristics.

STUDY DESIGN, SIZE, DURATION

Longitudinal data for the first five waves (2000-2012) of the UK Millennium Cohort Study were used, which is a two-stage sample of all infants born in 2000-2001 and resident in the UK at 9 months of age, drawn from the Department of Social Security Child Benefit Registers. A final sample of N = 15 218 children (125 IVF and 61 ICSI), from 14 816 families was used. Information was available for all waves for 8298 children. Four additional follow-up surveys were conducted in 2003, 2005, 2007 and 2012.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Our sample includes children born within a union (married or cohabiting parents) and where information on cognitive scores was available for at least two measurement points. Cognitive development was assessed with the British Ability Scales. At age 3 and 5 years (wave 2 and 3), children completed the naming vocabulary component, which measures expressive verbal ability. At age 7 years (wave 4), verbal cognitive abilities were assessed through the word reading test, and at age 11 years (wave 5) through a verbal similarity test. Two-tailed Student's t-tests examined differences between ART and NC groups. Growth curve models (random-coefficient, latent trajectory models) were used to study the effect of ART, confounding parental characteristics and health outcomes at birth, both at a baseline level of cognitive ability at age 3 years and on its growth rate.

MAIN RESULTS AND THE ROLE OF CHANCE

At age 3 and 5 years, children conceived with the aid of ART have higher verbal cognitive abilities than NC children (P < 0.001) but this consistently decreases over time and diminishes by age 11 years. Parental environment and resources are pivotal in children's cognitive development.

LIMITATIONS, REASON FOR CAUTION

The sample size of the ART cohort of children is small across each time period (N = 150-180) in comparison with NC children (N = 10 496-11 955). Owing to a limited sample size, we are also unable to compare IVF versus ICSI treatment.

WIDER IMPLICATIONS OF THE FINDINGS

With the increasing use of IVF and ICSI, these results indicate that there are no detrimental effects on children's early cognitive outcomes up to age 11 years, and highlight the importance of parental characteristics.

STUDY FUNDING/COMPETING INTEREST(S)

Funding for this project was provided by the European Union's Seventh Framework Program (FP7 2007-2013) (No. 320116 Families and Societies), ESRC/NCRM SOCGEN Grant (ES/N0011856/1) and the SOCIOGENOME ERC Consolidator Grant (ERC-2013-CoG-615603) (to M.C.M.). The authors have no competing interests to declare.

TRIAL REGISTRATION NUMBER

N/A.

New evidence about effects of reproductive variables on child mortality in sub-Saharan Africa

There is still considerable uncertainty about how reproductive factors affect child mortality. This study, based on Demographic and Health Survey data from 28 countries in sub-Saharan Africa, shows that mortality is highest for firstborn children with very young mothers. Other children with young mothers, or of high birth order, also experience high mortality. Net of maternal age and birth order, a short preceding birth interval is associated with above average mortality. These patterns change, however, if time-invariant unobserved mother-level characteristics of importance for both mortality and fertility are controlled for in a multilevel-multiprocess model. Most importantly, there are smaller advantages associated with longer birth intervals and being older at first birth. The implications of alternative reproductive 'strategies' are discussed, taking into account that if the mother is older at birth, the child will also be born in a later calendar year, when mortality may be lower.

It's not just about the future: The present payoffs to behaviour vary in degree and kind between the rich and the poor

Pepper & Nettle offer a nuanced and humane view on poverty that should be required reading for policy makers, particularly those interested in "behaviour change" policy. We suggest, however, that the emphasis on "future-discounting" in this paper downplays the importance of differences in the payoffs to behaviours in the present and how these payoffs may be realised in different currencies.

Impact of the global financial crisis on low birth weight in Portugal: a time-trend analysis

Background

The 2007–2008 global financial crisis had adverse consequences on population health of affected European countries. Few contemporary studies have studied its effect on perinatal indicators with long-lasting influence on adult health. Therefore, in this study, we investigated the impact of the 2007–2008 global financial crisis on low birth weight (LBW) in Portugal.

Methods

Data on 2 045 155 singleton births of 1995–2014 were obtained from Statistics Portugal. Joinpoint regression analysis was performed to identify the years in which changes in LBW trends occurred, and to estimate the annual per cent changes (APC). LBW risk by time period expressed as prevalence ratios were computed using the Poisson regression. Contextual changes in sociodemographic and economic factors were provided by their trends.

Results

The joinpoint analysis identified 3 distinct periods (2 jointpoints) with different APC in LBW, corresponding to 1995–1999 (APC=4.4; 95% CI 3.2 to 5.6), 2000–2006 (APC=0.1; 95% CI −050 to 0.7) and 2007–2014 (APC=1.6; 95% CI 1.2 to 2.0). For non-Portuguese, it was, respectively, 1995–1999 (APC=1.4; 95% CI −3.9 to 7.0%), 2000–2007 (APC=−4.2; 95% CI −6.4 to −2.0) and 2008–2014 (APC=3.1; 95% CI 0.8 to 5.5). Compared with 1995–1999, all specific maternal characteristics had a 10–15% increase in LBW risk in 2000–2006 and a 20–25% increase in 2007–2014, except among migrants, for which LBW risk remained lower than in 1995–1999 but increased after the crisis. The increasing LBW risk coincides with a deceleration in gross domestic product growth rate, reduction in health expenditure, social protection allocation on family/children support and sickness.

Conclusions

The 2007–2008 global financial crisis was associated with a significant increase in LBW, particularly among infants of non-Portuguese mothers. We recommend strengthening social policies aimed at maternity protection for vulnerable mothers and health system maintenance of social equity in perinatal healthcare.

Work-family life courses and metabolic markers in mid-life: evidence from the British National Child Development Study

Background

Previous studies have found generally better health among those who combine employment and family responsibilities; however, most research excludes men, and relies on subjective measures of health and information on work and family activities from only 1 or 2 time points in the life course. This study investigated associations between work-family life course types (LCTs) and markers of metabolic risk in a British birth cohort study.

Methods

Multichannel sequence analysis was used to generate work-family LCTs, combining annual information on work, partnership and parenthood between 16 and 42 years for men and women in the British National Child Development Study (NCDS, followed since their birth in 1958). Associations between work-family LCTs and metabolic risk factors in mid-life (age 44–45) were tested using multivariate linear regression in multiply imputed data.

Results

Life courses characterised by earlier transitions into parenthood were associated with significantly increased metabolic risk, regardless of attachment to paid work or marital stability over the life course. These associations were only partially attenuated by educational qualifications, early life circumstances and adult mediators. The positive association between weak labour markets ties and metabolic risk was weaker than might be expected from previous studies. Associations between work-family LCTs and metabolic risk factors did not differ significantly by gender.

Conclusions

Earlier transitions to parenthood are linked to metabolic risk in mid-life.

First-birth Timing, Marital History, and Women's Health at Midlife

Despite evidence that first-birth timing influences women's health, the role of marital status in shaping this association has received scant attention. Using multivariate propensity score matching, we analyze data from the National Longitudinal Survey of Youth 1979 to estimate the effect of having a first birth in adolescence (prior to age 20), young adulthood (ages 20-24), or later ages (ages 25-35) on women's midlife self-assessed health. Findings suggest that adolescent childbearing is associated with worse midlife health compared to later births for black women but not for white women. Yet, we find no evidence of health advantages of delaying first births from adolescence to young adulthood for either group. Births in young adulthood are linked to worse health than later births among both black and white women. Our results also indicate that marriage following a nonmarital adolescent or young adult first birth is associated with modestly worse self-assessed health compared to remaining unmarried.