Fatherhood timing and men's midlife earnings: A within-family study of Finnish cohorts born in 1938-50.

Fathers tend to achieve higher earnings than childless men, but there is limited evidence on the associations between fatherhood timing and men's later earnings. Using a longitudinal census-based sample of Finnish men, including a subsample of brothers, we investigated fatherhood timing and men's midlife earnings using both between- and within-family models. Earnings around age 50 were lower among adolescent and young fathers than for men who became fathers at ages 25-29 or later, but these associations became negligible after accounting for measured confounders and unobserved familial confounding. Overall, our findings highlight the important roles of selection into early childbearing and into childlessness. At the population level, early fatherhood was associated with clear negative distributional shifts in fathers' midlife earnings. However, among all men, any influence of fatherhood timing on men's midlife earnings distribution paled in comparison with that of childlessness.

Does having siblings really protect against childhood atopic diseases? A total population and within-family analysis.

The association between having older siblings and decreased risk for atopic symptoms is well-established. This has been interpreted as evidence for the microbiota hypothesis, i.e. that increased early-childhood microbial exposure caused by siblings protects from immune hypersensitivities. However, possible confounders of the association have received little attention. We used register data on Finnish cohorts born in 1995-2004 (N = 559,077) to assess medication purchases for atopic diseases: antihistamines, eczema medication, asthma medication and Epinephrine. We modelled the probability of atopic medication purchases at ages 0-15 by birth order controlling for important observed confounders and all unobserved genetic and environmental characteristics shared by siblings in a within-family fixed effects model. We further studied medication purchases among first-borns according to the age difference with younger siblings to assess whether having younger siblings in early childhood is beneficial. Having older siblings was associated with a lower probability of atopic medication purchases. Compared to first-borns, the probability was 10-20% lower among second-borns, 20-40% lower among third-borns, and 30-70% lower among subsequent children, depending on medication type. Confounding accounted for up to 75% of these differences, particularly for asthma and eczema medication, but significant differences by birth order remained across all medication types. Among first-borns, a smaller age difference with younger siblings was related to a lower likelihood of atopic medication use. Our results, based on designs that account for unobserved confounding, show that exposure to siblings in early childhood, protects from atopic diseases, and thus strongly support the microbiota hypothesis.

Birth size, school performance and family social position: a study of 650,000 children.

BACKGROUND: Low birth weight (BW) is associated with lower cognitive functioning, but less is known of these associations across the full range of the BW distribution and its components. We analyzed how BW, birth length (BL) and birth ponderal index (BPI, kg/m3) are associated with school performance and how childhood family social position modifies these associations. METHODS: Medical birth records of all Finnish children born in 1987-1997 were linked to school performance records at 16 years of age (N = 642,425). We used population averaged and within-siblings fixed-effects linear regression models. RESULTS: BL showed a linear and BW a curvilinear association with school performance whereas for BPI the association was weak. The strongest association was found for BL explaining 0.08% of the variation in school performance in boys and 0.14% in girls. Demographic, gestational and social factors partly explained these associations. Similar but weaker associations were found within sibships. The association of BL with school performance was stronger at lower levels of family social position. CONCLUSION: BL shows a linear association with school performance and can explain more school performance variation than BW. At the population level, BL can offer useful information on intrauterine environmental factors relevant for cognitive performance. IMPACT: Birth length is linearly associated with school performance in late adolescence and explains a larger proportion of school performance variation than birth weight. The association between birth length and school performance is stronger in families with lower socio-economic position. At the population level, birth length can offer information on the intrauterine environment relevant for later cognitive performance.

Minimum legal drinking age and alcohol-attributable morbidity and mortality by age 63 years: a register-based cohort study based on alcohol reform.

BACKGROUND: Minimum legal drinking age (MLDA) is an effective policy tool in preventing youth drinking and short-term alcohol-attributable harm, but studies concerning long-term associations are scarce. METHODS: In this register-based, national cohort study, we assessed alcohol-attributable morbidity and mortality of cohorts born in 1944-54 in Finland. Data were from the 1970 census, the Care Register for Healthcare (maintained by the Finnish Institute of Health and Welfare), and the Cause-of-Death Register (maintained by Statistics Finland). As MLDA was lowered from 21 years to 18 years in 1969, these cohorts were effectively allowed to buy alcohol from different ages (18-21 years). We used survival analysis to compare their alcohol-attributable mortality and hospitalisations with a 36-year follow-up. FINDINGS: Compared with the first cohort (1951) allowed to buy alcohol from age 18, the hazard ratios (HRs) for alcohol-attributable morbidity and mortality were lower in cohorts who could not buy alcohol until age 20 or 21 years. For alcohol-attributable morbidity in those aged 21 years when the reform took place, HR was 0·89 (95% CI 0·86-0·93) for men and 0·87 (0·81-0·94) for women versus those aged 17 years. For alcohol-attributable mortality, HR was 0·86 (0·79-0·93) for men and 0·78 (0·66-0·92) for women aged 21 years when the reform took place. The outcomes of the later-born 1952-54 cohorts did not differ from the 1951 cohort. INTERPRETATION: Earlier cohorts had consistently lower alcohol-attributable mortality and morbidity; however, other simultaneous increases in alcohol availability probably contributed to increased alcohol-related harm among the younger cohorts. Overall, differences between cohorts born only a few years apart highlight late adolescence as a crucial period for the establishment of lifelong patterns of alcohol use and suggest that higher MLDA could be protective for health beyond young adulthood. FUNDING: Yrjö Jahnsson Foundation, Foundation for Economic Education, Emil Aaltonen Foundation, Academy of Finland, European Research Council, and NordForsk.

The association of lowered alcohol prices with birth outcomes and abortions: A population-based natural experiment.

BACKGROUND AND AIMS: Alcohol use during pregnancy remains an important risk factor for adverse birth outcomes, but little is known regarding how alcohol prices affect pregnancy outcomes on the population level. We assess the associations between decreased alcohol prices with birth outcomes and abortions. DESIGN: Using national registers, we used interrupted time-series modelling to compare outcomes of pregnancies conceived before and after a tax cut, resulting in 33% mean decrease of off-premise alcohol prices on 1 March 2004. We also addressed possible heterogeneity of the associations by maternal age and household income. SETTING: Finland. PARTICIPANTS: All registered pregnancies starting 2 years before and 1 year after the alcohol price cut (analysis sample consisted of 169 735 live births and 32 441 abortions). MEASUREMENTS: The outcomes were birth weight, gestational age, the probability of low birth weight (< 2500 g at birth), preterm birth (< 37 weeks of gestation), any congenital malformations and share of registered abortions of pregnancies. FINDINGS: On the population level, lowered alcohol prices were associated with an increase in abortions immediately after the price cut [+0.84 percentage points; 95% confidence interval (CI) = 0.2, 1.4]. For birth outcomes, negative associations were observed among women in the lowest income quintile; for example, increased probabilities of low birth weight (+1.5 percentage points; 95% CI = 0.4, 2.6) and preterm birth (+1.98 percentage points; 95% CI = 0.8, 3.2). All changes were strongest immediately after the price cut and attenuated during the course of the following year. CONCLUSIONS: Lowered alcohol prices in Finland were associated with a short-term increase in adverse birth outcomes among low-income mothers and an overall increase in abortions.