That's a good question. More should ask it. Start with the premise that all babies need their person. That evolution. Donald Winnicott, pediatrician, and psychoanalyst, once said, There's no such thing as a baby, only a baby and someone. Throughout history, babies had their person. As women became more independent for the first time in human evolution, our someone became multiple caregivers. Babies were handed around to whoever could care for them. But, even Mother Teresa would not be enough. Everyone needs their own person in infancy and maybe for life. We can pretend babies won't mind because they can't talk, and besides, we need to make a living if we are ever going to have a nice house for them or tuition for college if not food on the table.
However, babies start making synaptic connections as soon as there is anything going on. In infancy, are forming their identities and world views, for life. They are getting the picture. They learn more about who they are and who the world is in the first year than any year to follow. They learn an encyclopedic vocabulary in their earliest years. Whatever they experience, whether domestic violence, being left or being adored, that becomes normal.
In the second year of life, they learn almost as much, as with the third year of life. From the bottom up, their self-worth and expectations are formed. Personalities are being laid down by the experiences they record in their brains for long term, as they cry or sit like cute little blobs, looking at us. They are learning language, attitudes, and all the givens, including what to expect. It's a bit complicated, because a very secure and adored infant can be forming and then get left due to mother's illness or work. This child has just had the rug pulled out from underneath her. She will spend her childhood, rather, her life, craving love and fearing it.
Should a toddler assume abuse, bad grammar, lack of communication, secrecy, worthlessness, threats or should she assume safety, trust, good grammar, meaningful communication, the expression of thoughts and feelings, transparency, and self-worth? What children experience is what adults assume.
I have a video of a mom hitting her six-month-old infant son on the head for crying, again and again. It was about a half-hour tape, which I never watched to the end to see him give up and stop crying so as not to be hit anymore. So, a child regularly hit on the head with a wooden spoon for crying, might be be great in the mafia some day: keep your wimpy feelings to yourself, but have no compunction against assaulting another. We imprint the ways of adults in infancy and toddlerhood, and then we re-enact these ways as adults.
If babies are spoken to about things that are relevant to them with repeated, learnable, or recognizable words and a vocabulary that grows according to use, then we have a very intelligent human-in-the-making, and if that little thing is not left on a regular basis, we have a very secure, intelligent human. If that little one is also adored and not left until kindergarten (like in the old days), then her self-worth can propel her to greatness, and she can handle just about anything, assuming mom cheers but doesn't help too much.
In the old days moms used to tote their babies everywhere. Like the kangaroo, human birthlings were carried in arms, on hips, slings, and pouches when mothers worked, or they were set up nearby to watch mommys every move in a cradle, crib or even a playpen.
I believe the correct protocol is to educate the parents on what the critical childhood essential needs are; how to correct missed opportunities; how to correctly discipline and coach; and finally, how to change the trajectory of the child's development, rather than correct the child so the parents can enjoy/love the child more. The healer should be the parents. The parents made the mistakes and can correct them far better than anyone, even Mother Teresa. No one can replace parents. Therapists can coach parents, given they know how.
Second, we need to find our niche. Then, take it on. Be curious. Make lots of mistakes trying. Fall down. Get up and try again. Let nothing stop you. Success and regard for others will give you your self-esteem. Learn relationship skills, especially how to give feedback and have a clean disagreement with regard. Expertise and the regard of others (because you regard them) will give you your self-esteem.