First 1000 days

The basis of “the first 1000 days” is that essentially the time between conception and around a child’s second birthday is a crucial window of opportunity to improve health.1  The concept was launched over 10 years ago, in 2010, by the then US Secretary of State Hillary Clinton.2  The reasons that this concept is so important has been well described by Darling and colleagues in a recent review.2

To paraphrase their publication the importance revolves around 4 key points.  Firstly, early intervention and hence prevention is better than cure.  Secondly, there is good evidence that many early life interventions in child health offer health benefits.  Thirdly, the early life environment is important for many aspects of health, for example, mental health, emotional health, and physical health.  Finally, the concept is a potentially powerful structure to inform child health policy.

Therefore, before conception and during fetal and postnatal growth and development, exposure to environmental factors, including altered nutrition, can cause adaptations to occur in the growing fetus and infant which may also be associated with adverse outcomes in childhood and later life, such as a greater risk of obesity3, type 2 diabetes, heart disease4-7, and allergy.8

Notable contributions to this literature have been made by a number of excellent long-term studies such as the British-based Avon Longitudinal Study of Parents and Children9,10 and the Dutch-based Generation R Study.11,12

A number of modifiable, important relationships between nutrition or nutritional status in mothers, fathers, infants, and young children and health outcomes in later life should be considered.

Pre pregnant nutritional status

For example, numerous studies over many years have shown a significant relationship between a mother’s pre-pregnant body mass index (BMI) and the risk of later overweight or obesity in her child.  A systematic review published in 2013 considered 45 such studies between 1973 and 2012.13  The odds ratio of a child being obese was 3 times greater if the mother was classified as obese before pregnancy when compared to a child from a mother classified as normal weight.  Many studies since this review have confirmed the relationship between parental pre-pregnancy BMI and later obesity, including some notable Australian data.14

Gestational weight gain

Excessive gestational weight gain has also been shown to be associated with a greater risk of overweight or obesity.  As an example, one such study from the UK’s Southampton Women’s Survey15 showed that excessive gestational weight gain, as defined by data from the US Institute of Medicine16, was associated with a significantly greater BMI in offspring at 4 years of age (0.22, 95%CI 0.07 – 0.03) and at 6 years of age (0.32, 95%CI 0.18-0.47).


Once born, breastfeeding confers many advantages to the infant.   Breastfeeding has been associated with a reduced risk of later overweight and obesity on many occasions, over many years. 17-21

Also, breastfeeding has been shown to protect against infectious diseases in industrialised countries during infancy22,23.  In Christensen’s recent study from Denmark23, for infants exclusively breastfed, the adjusted incidence rate ratio for hospitalization due to infections of any kind was 0.88 (95% confidence interval: 0.80–0.96; P = .006).

Introducing Solids

Although nearly all infant-feeding guidelines have typically recommended exclusive breastfeeding until around 6 months of age24 there is now evidence that introducing solids after 17 weeks, about 4 months, and before 6 months of age (while continuing breastfeeding) has potential benefits in terms of reducing the risk of some food allergies25-27  There may be an opportunity at this time for the child to develop appropriate immunological gut tolerance.26  In line with these findings, the Australasian Society of Clinical Immunology and Allergy) now state that;

“When your infant is ready, at around 6 months, but not before 4 months, start to introduce a variety of solid foods, starting with iron-rich foods, while continuing breastfeeding.”28, and,

“When introducing solid foods to your baby, include common allergy-causing foods by 12 months in an age-appropriate form, such as well-cooked egg and smooth peanut butter/paste. These foods include egg, peanut, cow’s milk (dairy), tree nuts (such as cashew or almond paste), soy, sesame, wheat, fish, and other seafood. Studies show that this may reduce the chance of developing food allergy in babies with severe eczema or egg allergy.”29


Nutrition and lifestyle factors throughout pre-conception, pregnancy, infancy, and early childhood can have a profound influence on a child’s development and long-term health.1  Also, the first 1000 days is a simple, evidence-based, and persuasive message for healthcare professionals, policymakers, and all others in the health care sector and should be embraced.2


  1. Davies PSW et al, Early life nutrition and the opportunity to influence long-term health: an Australasian perspective. Journal of Developmental Origins of Health and Disease (2016), 7(5), 440–448.
  2. Darling JC et al, The First Thousand Days: early, integrated and evidence-based approaches to improving child health: coming to a population near you? Arch Dis Child 2020;105:837–841.
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  23. National Health and Medical Research Council. Infant Feeding Guidelines. 2012. National Health and Medical Research Council: Canberra.
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  27. Accessed 6th May 2021
  28. Accessed 6thMay 2021