The sense of smell, or olfaction, is one of the earliest senses to develop and function in humans. Long before a baby can see clearly or fully process complex sounds, their olfactory system actively engages with the environment. This highly developed sense acts as a primary communication channel, playing a foundational role in biological development and early social bonding. For an infant, the ability to smell is directly linked to survival instincts and establishes recognition patterns while the baby is still in the womb.
Developing the Sense of Smell In Utero
The physical structures that enable a baby to smell begin forming early in gestation. Olfactory receptor neurons and nasal cavities develop around the sixth and seventh weeks of pregnancy. By the ninth week, the ciliated olfactory epithelium, which contains the sensory cells, is well-developed. The olfactory bulbs, which process scents, separate from the nasal cavity structures by approximately the thirteenth week.
Functional perception follows this anatomical development, with the fetus reacting to chemical signals in the amniotic fluid around the second trimester. The amniotic fluid transfers volatile aroma compounds from the mother’s diet into the fetal environment. By 24 weeks gestation, the fetus inhales and exhales this fluid, allowing odor-active molecules to reach the olfactory receptors.
The olfactory system intensifies maturation throughout the final trimester. Studies show that by 21 weeks, fetuses can discern different flavors and odors within the fluid. Exposure to specific scents from the maternal diet can influence the child’s odor and food preferences after birth. This prenatal learning demonstrates that the sense of smell is fully active before the baby takes its first breath.
How Newborns Use Olfaction for Survival
At birth, the sense of smell is the most highly developed sensory system, immediately guiding the newborn’s survival. The first and most profound use of this ability is identifying the mother. Within hours of delivery, newborns recognize and prefer the odor of their own mother’s amniotic fluid over that of another woman.
This innate recognition is crucial for initiating feeding, a process often described as chemotaxis, or movement guided by chemical signals. Odors emanating from the mother’s areolar glands (Montgomery’s glands) release specific scents that attract the infant. When a newborn smells these secretions, they display appetitive behaviors, such as increased mouthing, rooting, and head-turning, which direct them toward the breast.
The olfactory continuity between the amniotic fluid and the mother’s milk facilitates a seamless transition to nursing. The unique fragrance of breast milk is highly attractive to the baby, providing a calming effect. A mother’s familiar odor also acts as an emotional regulator, helping to soothe a crying infant and promoting security and comfort.
Encouraging Olfactory Development After Birth
Parents can support the continued development of their baby’s functional sense of smell after delivery. Maximizing skin-to-skin contact immediately following birth helps the infant solidify recognition of the mother’s unique scent and milk odor. This practice reinforces the strong olfactory link established in utero, which is foundational for bonding and feeding success.
It is beneficial to introduce varied, mild, and natural environmental scents as the baby grows. Parents can allow the baby to smell different foods while cooking or discuss the scent of fresh air or a mild flower. Avoiding harsh, strong chemical odors, such as certain cleaning products or strong perfumes, is important, as newborns can find these unpleasant or overwhelming.
Establishing comforting scent routines also provides emotional stability for the infant. Allowing the baby to sleep with a familiar, unwashed blanket or piece of clothing that carries the parental scent provides a sense of security during times of separation. By providing a safe and varied olfactory environment, parents help integrate this sense with the baby’s emotional and cognitive development.