Reply #100: There are many reasons why a woman w/ a baby would be less interested in sex

[Nikia]

I'm assuming that the Facebook picture is somewhat recent. Some are physical. Sometimes painful intercourse can persist months after giving birth. Breast feeding is good for the baby but it does hormonally decrease interest in sex. Some women have some degree of post partum depression. Often babies wake up at night making parents who awake to take care of them tired.
Aside from these, many couples do have trouble harmonizing their relationship with their roles as parents. A baby may bring a lot of stress to one's relationship and lifestyle even if both parents truly love their baby. I think that maybe you and your wife need to address these issues either by formal counseling or talking to a trusted family member or friend who remained married with children.