A In my opinion, "let the baby cry it out" is at the top of the list of bad baby advice. Why? For starters, any advice that goes against your instincts as a mother is probably advice you shouldn't follow. You know your baby better than anyone else and, in general, a mom's built-in intuition is fail-safe. It's a biological fact that a child's cries have an effect on his or her mother. When you hear your baby cry the blood flow to your breasts increases, accompanied by the urge to pick up and nurse your baby. (Nursing means comforting as well as breastfeeding.) As an added biological perk, the hormones released when you cuddle your baby or breastfeed her relax you, too, easing the tension you feel when you hear her cry. These physiological changes also make clear why the cry-it-out advice is easy for someone else to give, but difficult for you to follow.
For babies, crying is very valuable - in fact it's their language, and parents should pay attention. Your daughter is saying to you, in effect, "I need something. Something is not quite right here. Please make it right." Babies cry to communicate, not to manipulate. And, contrary to what you may have heard, crying is not "good for a baby's lungs." Nor is it good for your relationship with your child. If no one listens to an infant's cries, she will become very discouraged. What parents and babies then lose with this outdated advice is trust - your child loses trust in the value of her cries to communicate and you lose trust in your ability to respond to your infant's needs. By letting your baby cry it out, you desensitize yourself to her cries, going against your instinctive responses and possibly creating distance between you and your baby.
As your baby gets older, when and how quickly you respond to her cries will change. You can gradually lengthen your response time as your daughter learns how to soothe herself. As you and your baby get to know each other better in the early months, you'll eventually work out ways of answering her needs, knowing when to say yes and when to say no. With this sensitive approach, you're well on your way to developing a loving bond and mutual trust.