The First Thousand Days

1,440,000 seconds. 24000 hours. 1000 days. From conception to our second birthday. After almost 25 years of research, it is this period that AIGHD Senior Fellow, Dr. Tessa Roseboom, Professor of Early Development and Health has identified as the most critical to shaping who we grow up to be. From cognitive function to our food preferences, a “false start” in life has a massive influence. As Roseboom puts it: “The heart you build in the womb is the heart you die with.” 

Roseboom’s research began with studies on the Dutch famine during the WWII and the effects of high stress and malnutrition in mothers. Her findings have shown that the combination can increase children’s chances of various cardiovascular and metabolic diseases later in life as well as reduced performance in cognitive tasks. However, even when food is plentiful, the effects of food consumption on unborn children can be detrimental. Research has shown that children recognise, and prefer, the tastes they are exposed to in the womb, which makes healthy eating all the more important. It also doesn’t just take the stress of war to affect an unborn child: “We also see that normal variations in stress levels, mental health problems during pregnancy, air quality during pregnancy – even passive smoking can affect brain development,” says Roseboom.

The influence of these factors is not limited to the physical effects. Having the “proper building blocks and solid foundations can make a world of difference in your chances of living a healthy life.” Beginning life without the proper building blocks makes it more difficult for children to “concentrate in school, make friends, build relationships, as well as making individuals more susceptible to addictions and mental health problems.”

These factors then have large, measurable consequences for society as a whole. One of the many findings of the seminal Dunedin study examined the citizen’s societal costs, revealing that 80% of those costs, for example relating to criminal convictions and healthcare costs, are generated by just 20% of the population. Findings that have been echoed in Denmark and that Roseboom would “love” to test in the Netherlands. Shockingly, however, this study also concluded that those individuals in the 20% could be identified when they were as young as three.

While these effects are large, small changes can make big differences: Making the switch to a healthier diet or even simply interacting more with children can help with development: “Every hug you give your child, every time you read a book, do a puzzle – look at your child rather than looking at your phone, seeing what they’re interested in, what they’re doing, whether you can connect. These are all chances to build new connections in the brain that will help your child develop better. There is also what they call the skill multiplier effect, so once you’ve built all these connections it will be easier to learn new things in school.”

Perhaps the most startling example of this effect was revealed almost 30 years ago by Professors Betty Hart & Todd Risely, whose study revealed that three-year-old children who were frequently exposed to conversation knew more than double the words than children who were less exposed to conversation. Roseboom believes that this gap should not be underestimated: “You don’t have to be a scientist to know that if you are a 3-year-old and you have twice the number of words available to reach out to a friend, to tell their parents what you need or to tell the teacher what your plan is that puts you at a really big advantage. So, it really is this stacking of benefits if you can invest in really simple things like talking to your child or reading a book – it doesn’t have to cost money.” However, parenting is not a one-person job. It’s easier to expose your children to conversation, if both parents can be at home and this aspect is one where society can make some simple changes.

Until 2019, fathers in the Netherlands were only entitled to two days of paid parental leave. Now, by law, parents can take up to five weeks of leave. However, for example, in the United States of America there are no federal laws regarding parental leave and only four states offer paid parental leave.

Like all government intervention parental leave costs money but, with one eye on the aforementioned Dunedin Study, and another, more focused, on the “humanitarian perspective”, Roseboom believes that the decision is a simple one: “Evidence from all different fields of science show that investment in early human development is the best investment anyone can make.”

Nobel Prize winner and Professor of Economics at the University of Chicago, James Heckman has shown, through his studies on early human capital investment, that for every $1 invested in early childhood programs for disadvantaged children, society annually receives $1.13. Through better educational, economic, health, and social outcomes. This clear evidence, along with Roseboom’s work, has had an influence on national politics in the Netherlands, with plans for projects relating to the first thousand days being included in the current Dutch government’s manifesto. However, Roseboom would like to see more action at a European level: “We need to put much more effort into giving each child the best possible start in life, making that our priority would make a hell of a difference.”

Society has work to do and the media can help too. Roseboom recalls a call from a friend who panicked after eating a slice of cinnamon-loaded apple pie as the perfect example of a media culture that is content “blaming parents” and telling them what not to do, instead of reminding them: “You are important for your child, you are doing the best you can but you don’t have to do it alone. You can make mistakes; we all make mistakes.” Rather than stressing about cinnamon, Roseboom has some simple advice for parents: “Make sure you take good care of yourself: eat healthy, sleep enough, exercise enough and make sure you also get enough rest and relaxation.”


This story was originally published on the Amsterdam University Medical Center website.