Preterm children born below 33-35 weeks of gestation have an increased risk of mathematical difficulties.

AIM: To investigate the association between gestational age (GA) and grade point averages by domains of language and mathematics at the end of lower secondary education. METHODS: A nationwide register-based study including all Danish children born in 1992-1997 who completed lower secondary education. Grades were evaluated by GA. Domain-specific differences in grades were investigated, and academic profiles were made. RESULTS: The study population comprised 319 796 children. For language, only minor differences in grades were observed. The grades in mathematics ranged from 7.02 (95% confidence interval [CI]: 7.00-7.04) at GA = 40 weeks to 5.86 (95% CI: 5.61-6.11) at GA <28 weeks. Grade differences showed lower grades in mathematics, compared to language, below GA 33-35 weeks. The academic profile of mathematical difficulties was more prevalent among GA <32 weeks. Average/high grades within both domains represented the predominant academic profile, constituting 68.8% at GA 39-41 weeks and 56.6% at GA <28 weeks. CONCLUSION: Only in mathematics decreasing GA was associated with lower grades. Increased mathematical difficulties were found below GA 33-35 weeks. The academic profile of mathematical difficulties was more prevalent among GA <32 weeks. However, the absolute differences in grades were small, and the predominant academic profile was average/high grades within both domains across all GA.

Early life body size and its associations with adult bladder cancer.

Background: Adult overweight is a potential bladder cancer (BC) risk factor, but little is known about size earlier in life.Aim: To investigate if birth weight, childhood body mass index (BMI), height and growth are associated with adult BC.Subjects and methods: Anthropometric information from birth and ages 7-13 on 315,763 individuals born 1930-1989 in the Copenhagen School Health Records Register was linked to national registers. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated by Cox regression.Results: 1145 individuals (839 men) were diagnosed with BC. Sex differences were not detected. Childhood BMI had positive associations and height had inverse associations with BC; at age 13, HR = 1.10 (95% CI: 1.02-1.18) per BMI z-score and HR = 0.94 (95% CI: 0.89-1.00) per height z-score. A pattern of above-average increases in BMI from 7 to 13 years had higher hazards of BC than average increases. Above-average growth in height was not significantly associated with BC. Compared with birth weights of 3.5 kg, low (2.5 kg) and high (4.5 kg) values were associated with increased hazards of BC; HR = 1.26 (95% CI: 1.01-1.58) and HR = 1.36 (95% CI: 1.09-1.70), respectively.Conclusions: A high BMI, a short height, excess BMI gain in childhood and low and high birth weights are associated with increased hazards of BC.

Early life body size, growth and risks of systemic lupus erythematosus - A large Danish observational cohort study.

OBJECTIVES: Adult obesity may increase the risks of systemic lupus erythematosus (SLE), and there are genetic links between adult height and SLE. Thus, it is plausible that size earlier in life may be important in the aetiology of SLE as well. We investigated whether birthweight, childhood body mass index (BMI; [kg/m2]), height and growth are associated with risks of adult SLE. METHODS: The study included 346,627 children from the Copenhagen School Health Records Register, born 1930-1996 with measured weights and heights from 7-13 years. Birthweight information was available from 1936. Linkages were made to the Danish National Patient Register for information on registrations of SLE. During follow-up, 435 individuals (366 women) were registered with SLE. Cox proportional hazards regressions were performed to estimate hazard ratios (HR) and 95% confidence intervals (CI). RESULTS: No differences by sex were detected in any of the associations. Birthweight was not associated with SLE risks. Childhood BMI and height were positively and linearly associated with SLE risks. For BMI at age 7, the HR was 1.11 (95% CI: 1.01-1.23) per z-score. For height at age 7, the HR was 1.13 (95% CI: 1.02-1.24) per z-score. The estimates were similar in magnitude across all childhood ages for BMI and height. There were limited indications that change in BMI or growth in height during childhood influence the risks of SLE in adulthood. CONCLUSIONS: Childhood body size is associated with risks of adult SLE, which supports the hypothesis that early life factors are important in SLE aetiology.