As will be obvious to anyone on a bus or train or waiting for coffee, access to screen-based media has been revolutionised over the past two decades. In 2020, there were more than six billion smartphone users worldwide and almost global penetration. Yet, our understanding of how these devices have affected other behaviour, such as sedentary time, is limited.
In our study, recently published in the IJE, we used accelerometer measurements of sedentary time collected for the Norway-wide physical activity monitoring system to estimate that a 9-year-old boy or 15-year-old girl or boy spent, on average, 20 to 30 minutes more each day being sedentary in 2018 than in 2005. We also found that children and adolescents accumulate more of their sedentary time in longer uninterrupted periods, compared with a more fragmented pattern of activity in 2005. Children and adolescents now spend less time sitting for short periods of 5 minutes or less at a time.
Autism spectrum disorder (ASD) comprises a heterogeneous group of impaired neurodevelopmental conditions. The aetiology of ASD is complex and largely unclear, with some recent evidence suggesting the possibility of transmission of risk across multiple generations.
Our study, recently published in the International Journal of Epidemiology, evaluated the associations between birth characteristics of parents and the subsequent risk of ASD in their children.
Fetal undernutrition followed by abundant food after birth might be a recipe for disaster — it is linked to increased risk of obesity and cardiometabolic diseases later in life. The Dutch famine birth cohort study is a tragic “natural experiment” that exemplified this phenomenon. It observed that people born to mothers who experienced a transient period of severe famine during pregnancy, followed by a return to normal diet postnatally, had an increased risk of obesity and cardiometabolic diseases.
This mismatch between a poor fetal nutritional environment and a rich postnatal nutritional environment might cause fetal adaptive responses to become maladaptive, leading to greater cardiometabolic risk in adulthood. This is known as the developmental mismatch hypothesis.
However, is developmental mismatch still a pertinent health issue affecting cardiometabolic risk in contemporary well-nourished populations, who are not facing famine or drastic environmental stresses? In these populations, fetal undernutrition is more likely to result from uteroplacental insufficiency than maternal malnutrition.
For children in low-income countries, diarrhoea
remains a major cause of death and can lead to long-term health consequences. Accurate
estimates of childhood diarrhoeal illness are crucial to evaluating the success
of campaigns to defeat diarrhoea and improve health in countries where the
burden of diarrhoea is high.
In our study, recently published in the IJE, we found that caregivers may underestimate diarrhoeal diseases in children aged under 5 years when asked to recall whether the children had diarrhoea in the previous 2 weeks. Compared with a 1-week recall period, there was a consistent underestimation of the prevalence of diarrhoea across five countries in sub-Saharan Africa.
Cerebral palsy is the most common physical disability among children, with about two per 1000 live-born infants being diagnosed with the disorder. In most children with cerebral palsy, the disability is caused by damage to the immature brain during pregnancy or birth that results in problems with movement.
Denmark and Norway have low income inequality and free access to education and offer high-quality antenatal care to pregnant women free of charge. Nevertheless, in our study recently published in the International Journal of Epidemiology, we found that the risk of having a child with cerebral palsy in these two countries varies by the parents’ educational level, and this educational gradient has been surprisingly stable over time.
The Obstetrics and Periodontal Therapy (OPT) Study was an NIH-funded randomised controlled trial designed to evaluate whether periodontal treatment in pregnant women had any effect on preterm birth; its findings were published in 2006. The investigators randomly assigned about 800 women who had been pregnant for less than 16 weeks, and had periodontal disease, to one of two groups. One group received periodontal treatment during pregnancy, whereas the other group received treatment after pregnancy.
Although the study found that treatment controlled periodontal infection and reduced the microorganism load, there was no difference in preterm birth rates between the two groups. The investigators concluded that treating periodontal disease during pregnancy did not affect the risk of preterm birth. However, they also found that there were more stillbirths in the group that received treatment after pregnancy, suggesting that periodontal treatment may improve survival of fetuses. The potential bias resulting from the intervention affecting both the outcome (in this case, preterm birth) and survival (in this case, stillbirth) was acknowledged as a limitation.
Childhood overweight and obesity are a global public health problem. In high-income countries, obesity follows socioeconomic patterns, in that people with a lower socioeconomic position are more likely to be overweight or obese than those with a higher socioeconomic position. Poor diet is a key risk factor for excess weight gain. It is also a risk factor that we can do something about.
Reducing child mortality remains one of the key objectives of the Sustainable Development Goals. Remarkable progress has been made over the past 25 years, with the global number of deaths of children aged under 5 falling from 13 million in 1990 to six million in 2015. Yet little is known about the relative contributions of specific public health interventions and general improvements in socioeconomic status and educational attainment over the same period.
Johanna Metsälä, Jaakko Nevalainen and Suvi M Virtanen
Traditionally, asthma and type 1 diabetes have been considered distinct immune-mediated diseases in which the underlying immune responses counteract each other, resulting in an inverse association between the diseases. In our study, recently published in the IJE, we explored the association between asthma and type 1 diabetes in childhood in a novel way, and observed that the direction of the association is dependent on the order of appearance of the diseases.
Tanja AJ Houweling, David Osrin, Kishwar Azad, Dharma S Manandhar, Prasanta Tripathy, Tambosi Phiri, Joanna Morrison and Anthony Costello
In low- and middle-income countries, the odds of surviving the first 28 days of life are grossly unequal between infants born in deprived and better-off families, even among children living in the same community. In our study, recently published in the IJE, we have shown that women’s groups are able to address this problem. Under the guidance of a facilitator, women came together every month to discuss problems during pregnancy, delivery and the newborn period, and then designed and implemented strategies to overcome these problems with the help of the entire community.