Fetal Senses and Development

Movement: Probably the first big milestone of fetal development is the heartbeat. Amazing how quickly this big step is taken; at about three weeks of gestational age (g.a.). This is often near the time a mother is first realizing she is pregnant. So soon and already the fetal movements are beginning. By week ten, but as early as week six, a fetus is moving, stretching and turning it's head and limbs about. Within another month a cycle of rest and wakefulness is established ad the fetus begins interacting with its environment. It is also responsive to the world outside the womb by week fifteen at the latest; reacting to laughter, sneezing, coughing and other movements by the mother.

Taste and Smell: Science has now linked these two senses more closely together with the discovery of taste buds and olfactory receptors that are highly complex. While we knew that fetus' could taste in the womb, it was only in recent years that the ability of fetus' to smell was considered. As more research has been done on fetal responses to various stimuli, the complexities that have been discovered are astounding.

Over 120 different scents have been detected in the amniotic fluid that a fetus can "smell" by breathing in. If a mother lights up a cigarette her infant responds in negative ways; when a mother is drinking coffee a fetus reacts in ways that make it clear to researcher's they "recognize" the smell! (Regardless of whether the coffee was decaf or regular) It was known that scent played a big role in early breastfeeding success but now we are learning that the foundation for that recognition begins in the womb.

Hearing: A fetus begins listening and responding to sounds around it at about sixteen weeks of age, even though the development of the outer ear doesn't happen until around twenty-four weeks g.a. Voices reach the fetus, with the mother's voice being the most influential as it is heard not only from outside the womb, but sound vibrations are actually carried through the body as well. Pitch, tone, and speech rhythms are all reacted to by the fetus. Some sounds even affect the metabolism of the fetus.

Vision: An interesting fact I uncovered in my studies was that even when a fetus' eyelids are fused shut (until around twenty-six weeks g.a.) the baby has no trouble recognizing and reacting to a disturbance in it's environment. They "seem to be using some aspect of "vision" to detect the location of needles entering the womb, either shrinking away from them or turning to attack the needle barrel with a fist" (Birnholz, Stephens, and Faria, 1978). Twins are observed to be playing with each other in utero, even holding hands.

A newborns eyes are focused at a distance as 8-12 inches, which is the exact distance of the mother's face when breastfeeding. They also have a great sense of contrast, which is the reason why a mother's areola darkens during pregnancy, allowing a newborn to more easily find the breast.

Other Developments: Fetus' also have been shown to react to pain both in their physical reactions to being nicked by a needle during an amniocentesis, and in their chemical hormone responses. Just few minutes after a needle prick a fetus "shows a 590% rise in beta endorphin and a 183% rise in cortosol"; a pain relieving hormone, and a stress hormone. Evidence they feel pain in utero.

Another interesting thing is the recent discovery that fetuses dream. Premature babies have been observed in states of Rapid Eye Movement or REM during sleep times. Babies dream with REM as early as 23 weeks and respond in movement and facial expressions to their dreams.

I wonder what babies dream about before they are born, don't you? It was amazing, and humbling, to me to realize how much impact I already had on my babies even before they were born. Hope they enjoyed my singing in the shower at the top of my lungs!

See other childbirth education articles by Angela England