While babies use crying as a medium of communication during their youngest months, you won't find any tears accompanying it. The reason is not lack of emotion, but a particular gland, which takes time to develop.
Tears are not only a mode of expressing our feelings, but they are necessary to protect the eyes and keep them moist. According to Sage Timberline, a pediatrician at the University of California, Davis, Children's Hospital in Sacramento, California, when faced with extreme emotions such as sadness, anger or even happiness, we cry. The stress activates a fight or flight response which generates tears to protect the eyes consequently.
These emotional tears can also release stress-inducing hormones that may have been building up during tough times; contributing to that sense of relief that follows a good cry, she told Live Science. The tear-producing glands, lacrimal glands may sometimes take two months to develop fully.
“How much we actually cry depends on how good the drainage system is, versus how much tears the glands produce," Dr. Phillipa Sharwood, a Brisbane-based pediatric ophthalmologist and member of the Royal Australian and New Zealand College of Ophthalmologists, told Mamamia.
An infant is born with tear ducts that are not fully developed until the first few weeks. The ducts do contain enough tear to keep the eyes moist, but not as much to form a droplet that can roll down the cheek.
Just as the tear ducts, the sweat glands to are not fully developed initially. There are two types of sweat glands – eccrine and apocrine glands. Apocrine glands are activated during the hormonal changes taking place in puberty. It secretes sweat through hair follicles that is odorless initially and is filled with electrolytes and water along with lipids, steroids, and proteins — which bacteria can process to produce odors.
The Eccrine glands start to form during the fourth month of pregnancy and spread all through the body steadily. It first appears on the palms and soles of the feet, covering the entire body by the fifth month.
Timberline said after a baby's birth, the most active eccrine glands are the ones on the forehead. And thus, soon after, they start sweating on his or her torso and limbs. As infants are unable to sweat appropriately, the caregiver takes care of their body temperature by keeping an eye on the various signs, like warm, flushed skin, rapid breathing, fussiness, and decreased activity of arms and legs, Timberline said. They further do the needful to remove the inconvenience caused to the baby.
While their tear and sweat glands aren't fully developed, they can surely cry their heart out without shedding a drop of tear. And in case some babies sweat a lot, so there's nothing to sweat over because that's also normal!