In this paper we analyse the relationship between happiness and childbearing taking a comparative perspective. We argue that fertility and happiness are somewhat linked and we investigate whether there are important differences across European countries. Using happiness as a well-being measure offers important benefits over income especially when interest lies in understanding how individuals' wellbeing is associated with childbearing outcomes. We use the European Social Survey (ESS) and apply simple regression techniques, controlling for country differences, and find indeed a positive and significant association between happiness and childbearing. However, this association depends, especially for mothers, on location, partnership status, income levels and job status.

BACKGROUNDThis 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).METHODSThis 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.RESULTSSocial 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.CONCLUSIONSIt 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.

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.

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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.

Background Children born after medically assisted reproduction (MAR) are at higher risk of adverse birth outcomes than naturally conceived children. It is not known to what extent the excess risk should be attributed to harmful effects of the treatment or to pre-existing parental characteristics that confound the association. Methods We analysed birth weight, gestational age, risk of low birth weight, and risk of preterm birth among MAR-and naturally conceived children using Finnish population registers covering 65,634 children born in 1995-2000. First, we estimated the differences in birth outcomes by mode of conception in the general population using standard multivariate methods that controlled for observed factors (e.g., multiple birth, birth order, and parental socio-demographic characteristics). Second, we used a sibling-comparison approach that has not been used before in MAR research. We compared MAR-conceived children to their naturally conceived siblings, and thus controlled for all observed and unobserved factors shared by siblings. The latter analysis included 1245 children. Findings MAR-conceived children had worse outcomes than naturally conceived children for all outcomes, even after adjustments for observed child and parental characteristics (e.g., 60gr [95% CI:-34 to-86] lower birth weight; 2.2-percentage point [95% CI: 1•1 to 2•2] increased risk of preterm delivery). In the sibling comparison, the gap in birth outcomes was attenuated, such that the relationship between MAR and adverse birth outcomes was statistically and substantively weak for all outcomes (e.g., 31gr [95% CI:-22 to 85] lower birth weight; 1.6 percentage points [95% CI:-1•3% to 4•4%] increased risk of preterm delivery). Interpretation MAR-conceived children face an elevated risk of adverse birth outcomes. However, our results indicate that this increased risk is largely attributable to factors other than the MAR treatment itself. Funding European Research Council, the Academy of Finland, and the Signe and Ane Gyllenberg Foundation. Research in context Evidence before this study We searched for studies analysing the association between Medically Assisted Reproduction and birth outcomes within families who had at least one child conceived through MAR and one child conceived naturally, published in any language up until March 2018 (with no specified earliest date). We searched in PubMed and Google Scholar using relevant terms ("Medically Assisted Reproduction", "Assisted Reproductive Technology", "birth outcomes", "low birth weight", "preterm", "siblings", "within family"). We found only three studies that compared MAR-and naturally conceived children from the same families. These studies, which reported mixed findings, suffered from two major limitations. First, they relied on random-effects models, which are biased when unobserved random effects (e.g., measuring health) are correlated with observed covariates (e.g., maternal age, socioeconomic status). Second, they focused on children conceived through IVF only, and included chil...

STUDY QUESTION What are the socio-demographic characteristics of families in Norway who have children after assisted reproductive technology (ART), and have these characteristics changed over time? SUMMARY ANSWER Parents who conceive through ART in Norway tend to be advantaged families, and their socio-demographic profile has not changed considerably over the period 1985–2014. WHAT IS KNOWN ALREADY A small number of studies show that couples who conceive through ART tend to be socio-economically advantaged. STUDY DESIGN, SIZE, DURATION Norwegian Population Register, the Medical Birth Register and the national data bases were linked to study all live births in Norway between 1985 and 2014. PARTICIPANTS/MATERIALS, SETTING, METHODS The sample consisted of 1 757 768 live births. Simple bivariate analyses were performed to describe the socio-demographic characteristics of parents who conceived through ART and changes in these characteristics over the time period 1985–2014. We used linear probability models to estimate the association between parental income and giving birth after ART from 2000 to 2014, before and after adjustment for maternal age at delivery, education and area of residence. MAIN RESULTS AND THE ROLE OF CHANCE Parents conceiving through ART were more likely to be older, with the highest levels of income and education, and married. Their socio-demographic profiles did not change considerably during the period 1985–2014. In the unadjusted model, parents belonging to the top income quartile were 4.2 percentage points more likely (95% CI: 4.1 to 4.3) to have conceived through ART than parents who belonged to the bottom income quartile. Adjustment for maternal age only partially reduced the income disparities (for the top income quartile by 35% (β = 2.7 with 95% CI: 2.5 to 2.8)). Additional adjustment for maternal education, marital status and area of residence did not further attenuate the associations. LIMITATIONS, REASONS FOR CAUTION The data does not enable us to tell whether the lower numbers of children conceived through ART amongst more disadvantaged individuals is caused by lower success rates with ART treatment, lower demand of ART services or barriers faced in access to ART. The study focuses on Norway, a context characterised by high subsidisation of ART services. WIDER IMPLICATIONS OF THE FINDINGS Even though in Norway access to ART services is highly subsidised, the results highlight important and persisting social inequities in use of ART. The results also indicate that children born after ART grow up in resourceful environments, which will benefit their development and well-being. STUDY FUNDING/COMPETING INTEREST(S) This work was supported by European Research Council agreement n. 803959 (to A.G.), by Economic and Social Research Council grant ES/M001660/1 and by the Research Council of Norway through its Centres of Excellence funding scheme, project number 262700. The authors have no conflict of interest to declare. TRIAL REGISTRATION NUMBER Not applicable.

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.