UNICEF UK say:
Finding your rhythm
Having a new baby can be challenging, however as time goes by, you will start to understand what your baby needs. This will help you settle into a rhythm that is right for you both. Responding to your baby’s needs for food and comfort will help him feel secure, so he will cry less, which helps make your life easier too. Holding your baby when he is crying helps him to feel loved and secure, even if he doesn’t stop crying straight away.
Research shows that babies who are responded to in this way grow into more confident toddlers who are better able to deal with being away from their parents temporarily, rather than becoming clingy and spoilt. This again can help make life less stressful for you.
You should leave babies to settle alone so that they learn to be independent.
When babies are left alone they think they have been abandoned, and so become more clingy and insecure when their parents return.