A baby’s exposure to older siblings’ diseases can have repercussions for adult life

A baby’s exposure to respiratory infections from older siblings can have an impact on their adult life, according to a Danish study.

According to the study, babies who are exposed to respiratory infections from their older siblings fare worse in terms of education, earnings and health as adults.

The study highlights a situation familiar to many families with children: a child starts daycare, and soon the whole family is sick at home. According to the study, babies are particularly vulnerable to viruses brought by siblings.

According to N. Meltem Daysal, an associate professor of economics at the University of Copenhagen who participated in the study, it was found that a younger sibling has a two to three times higher risk of being hospitalized for a respiratory infection as a baby than an older sibling did at the same age.

The difference is particularly clear during the first six months, when children are biologically most vulnerable, the study says.

According to the study, a respiratory infection suffered during the first months of life can appear later in life.

Daysal says in the presentation of the study that when siblings are compared, it is seen that early exposure to diseases is associated with a lower probability of completing both a secondary education and a university degree. In addition, it can also be reflected in lower incomes later in life.

According to the researchers, the probability of children exposed to respiratory diseases as infants decreases by about 0.4 percentage points. As adults, their income is also slightly less than one percent lower on average.

In the study, the researchers followed more than 1.2 million Danish children from birth to adulthood.

The researchers compared siblings born in different order and used information on when and where respiratory infections occurred among young children.

In this way, the researchers say they were able to assess which differences in later life were specifically due to the illness in infancy and not, for example, family background.

The researchers say the results suggest that preventing babies from getting sick, such as through vaccinations and good hygiene, could have far-reaching effects.

The study was originally published in the American Economic Review.