The first 1001 days of life, from conception to age two, is a time of unique opportunity and vulnerability. It is a period of particularly rapid growth, when the foundations for later development are laid.
“The period from pregnancy to age three is when children are most susceptible to environmental influences. Investing in this period is one of the most efficient and effective ways to help eliminate extreme poverty and inequality, boost shared prosperity, and create the human capital needed for economies to diversify and grow.”
Unicef, World Bank and World Health Organisation Nurturing Care Framework
It is now widely recognised that what happens in the first 1001 days of life are incredibly important. Children’s brains develop fastest and are at their most ‘plastic’ or adaptable in the womb and early years of life. During this time, many millions of neural connections are made and then pruned. This builds the architecture of the brain upon which other forms of development will rest.
Babies’ development is strongly influenced by their experiences of the world. These are shaped by their primary caregivers (usually their parents). Parent-infant relationships are vitally important.
“Young children experience their world as an environment of relationships, and these relationships affect virtually all aspects of their development." 
Babies are reliant on parents to respond to their needs. Parents who are tuned-in and able to respond to babies’ needs sensitively in an appropriate and timely way, support their early development in profound ways:
- Parents’ responses shape how babies experience their emotions and how they learn to regulate and express these emotions. If someone responds sensitively to a baby when they cry, for example, the baby learns that they matter, that they can rely on their parents to help them when they are upset, and how difficult emotions can be brought under control.
- When babies receive appropriate comfort and care, they can feel safe and begin to explore the world around them, to play and learn.
- When parents provide positive, playful interactions, and when they engage in play and activities such as singing and reading to their baby, this provides stimulation that helps a child to learn and develop.
Nurturing relationships begin before birth. The foetal brain is developing rapidly during pregnancy and is influenced by the physical environment of the mothers’ womb, and the environment beyond it. Babies can experience adversity in the womb. For example, where domestic abuse is occurring, research shows that babies’ stress regulation systems adapt accordingly, leaving them more responsive to threat but consequently more irritable and difficult to settle once they are born.