Here is an article that might be helpful. It's from the Natural Child Project website, they have tons of AP articles you might want to look at also. This one has comments about separation.
Attachment And Separation: What Everyone Should Know
by Dr. Peter Cook
Many human troubles would be lessened if the emotional needs of infants and young children were better understood in our society. This applies particularly to attachment needs and the effects of separating infants from their parents.
Can you imagine how you might feel if you were happily married, and your partner suddenly disappeared for a week or two, and then reappeared without explanation, expecting to carry on as if nothing had happened? And what if he or she were holding someone else? Many toddlers have been in a situation like this when their mothers had a new baby. Infants, by definition, are children who are too young to talk, and they cannot understand the future when repeatedly told that "Mummy will come back soon".
The survival of all animals who breastfeed their young has, throughout their long history, depended on Nature's way of keeping the mother and her young together, both for nourishment and protection. Some animals, such as lambs can follow their mothers from birth, but "higher" animals such as chimpanzees, and especially human beings, are too immature when they are born to follow their mothers in this way, and instead they are normally carried about by their mothers, at first in her arms, and later on mother's back.
For this to happen, Nature has provided a process of "bonding", so that normally a mother becomes attached to her particular baby, making her want to stay near him or her and respond to any crying or other signals. Successful bonding is helped by keeping mother and baby together in the early hours and days after delivery and breastfeeding. If they are separated at this time bonding may not occur normally. In many animals, and sometimes in humans, this may lead a mother to reject her baby. Nature's pattern seems to be that mothers and infants are designed to stay close to each other and in physical contact for much of the time, especially in the first year of life, while mother goes about her activities. Breastfeeding is part of Nature's pattern, to work with attachment behavior in developing a close, warm, and pleasurable mother-infant relationship. In humans, for better or for worse, these are the early days in a relationship which, in some form or other, will be lifelong. It may be that one day this baby will care for the mother or father.
Babies' wants are much the same as their needs, and they will signal these needs to their mothers when they are thirsty, or wanting to be cuddled or see what is going on. Babies need their mothers and other carers to be sensitive and responsive to their signals. Through this responsive relationship, mother infant "attunement" normally develops, in which the interactions of mother and baby are like a coordinated "dance", which forms the basis for later communication and language development.
We know now that ideas that such care will "spoil" a baby have been mistaken. 0n the contrary, responsive mothering is a good basis for the infant's present and future well-being. As the baby becomes older he or she in turn develops strong attachment bonds to the mother, and, hopefully, also to the father and others, thus providing a "secure base" for learning about the world.
In natural conditions, infants separated from their mothers could be in great danger, and, over time, only those infants with an instinctive concern to stay somewhere near their mothers were likely to survive to produce the next generation. So this same instinctive concern is usually seen in infants today. This is the basis of the "separation anxiety" which normal infants often show, if they cannot re-unite with their mothers, or someone who provides their secure base. Infants may develop attachments to other members of the family or carers, who can take mother's place for a while. But if mother does not return soon, some infants can become quite distressed, with crying and an increase of behaviors designed to bring the mother and infant together again. If the separation lasts for some days, the first state of crying and "protest" may be replaced by a mood of quiet unhappiness or despair. In the first two or three years of life an infant has no adult sense of time, and since explanations cannot be understood, the infant seems to despair of the mother's return, in a kind of grief or mourning reaction.
It is painful to go on experiencing such hurt, angry and even depressed feelings, and eventually the infant may pass into a state which has been termed "detachment". It may be thought that the child has "settled", and he or she may appear happy. He may be friendly to almost anyone, except to his mother if she re-appears. Children in this state will often turn away from their mothers or appear not to recognize them. It seems that they cannot bear to have the feelings of hurt and longing brought up again. These reactions are more likely when the child is away from home and in a strange environment. They may be less, or absent, if the child has good substitute mothering, preferably from a known member of his or her own family, throughout the period of separation.
If the separation is unavoidable it is desirable that the mother and infant should visit each other whenever possible, even if this appears to upset the infant at the time. It is more healthy for this crying and upset to come to the surface, than for it to be bottled up for later on. This particularly applies if a toddler's mother goes to hospital to have another baby. It also applies if an infant or young child has to go to hospital, and in such cases it is often desirable for the mother and/or another member of the family to spend time helping to care for the child in the hospital, if medical and family circumstances are suitable.
If such separation in early childhood is not well handled, sensitive children may be emotionally disturbed for a considerable time afterwards. It is believed that children aged 6 months to 4 years are more particularly vulnerable. On reunion with mother after a separation it is helpful if the mother can recognize what her child has been feeling. It is important to understand and accept the feelings of hurt, anger and sadness which may come to the surface, perhaps with clinging and babyish behavior, as the child seeks to clear the way to develop once again a trusting, loving and co-operative relationship with his parents. This is one of Nature's healing processes which should be handled with gentle respect and acceptance, not punishment.
Note: An excellent account for the general reader may be found in the book Becoming attached: unfolding the mystery of the infant-mother bond and its impact on later life. Karen, Robert. New York: Warner, 1994.
This article is based on "Attachment and Separation: What Everyone Should Know", brief invited statement in the Annual Report for 1976-7, Royal Far West Children's Health Scheme, Sydney. (Revised March 2000.)
Published with permission of the author.