Some historians who really ought to have known better used to say that parents in the Middle Ages did not love their children. This is of course totally false--they loved them, cared for them, and mourned them if they died.
The reasons advanced for why they didn't love them were that medieval children were expected to take on adult roles sooner than they do in our society (not sure how this works for the argument), and that since infant mortality was higher than it is now, parents "must" have become indifferent to losing children. No, they just were sad a lot.
Human infants, born totally helpless, are much more vulnerable when young than, say, baby cows and horses, which can walk almost from birth. They have to be held carefully, nursed, and kept warm and dry. Any mother, having suffered through nine months of pregnancy and the pains of childbirth, would not be indifferent to the new baby.
Medieval childbirth was overseen by midwives, not doctors. Although their success rate did not match that of the modern West, they did have better luck than did nineteenth-century doctors, who used chloroform enthusiastically and often came straight to a birthing from attending someone with a nasty disease. Medieval women also gave birth sitting up or at most reclining, having the help of gravity to ease the baby along, rather than lying on their backs with their feet in the air, the twentieth-century practice.
A new baby needs to start feeding very soon; childbirth, being squeezed through a too-narrow passage, is as tough on the baby as the mother. (Cesarian birth was not possible without modern surgical techniques and was only resorted to when the mother was dying anyway, to try to save the child.) Sometimes now a baby is so exhausted that she does not drink properly. Or sometimes the mother does not produce enough milk. These days the answer is easy--hitch the baby up to an IV feed until she gets a little strength back, and then give her baby formula. Neither of these were possible in the Middle Ages.
A child who did not drink properly was going to fade away very quickly. So was a baby who caught the kind of disease that modern antibiotics now clears right up, or that can be prevented with modern vaccinations. The first year or so was an especially dangerous time.
Peasant women nursed their babies for longer than modern babies are nursed, generally for a good two years. Without pureed baby food that comes in little jars, they wanted to make sure the children would be ready for chewy solid food. Nursing also provided a partial form of birth control. Well-to-do urban mothers and aristocratic women, however, often employed wet nurses.
A wet nurse would be someone with an infant of her own, who had been nursing for a while so that the mother clearly had an excellent supply of milk. She could make a good income from fostering a noble woman's baby on the other breast. Many aristocratic infants spent the first two years of their lives with their nurses, only returning to their birth family when they were ready for solid food.
Continue the story with medieval seven-year-olds.