Baby's Alertness in the Womb
Asleep and Awake
From early on in your pregnancy, your baby is more like a newborn than you might think. He sleeps, moves around, listens to sounds, and has thoughts and memories. Here's how:
Just like newborns, fetuses spend most of their time sleeping. At 32 weeks, your baby sleeps 90 to 95 percent of the day. Some of these hours are spent in deep sleep, some in REM sleep, and some in an indeterminate state -- a result of his immature brain. During REM sleep, his eyes move back and forth just like an adult's eyes. Some scientists even believe that fetuses dream while they're sleeping! Just like babies after birth, they probably dream about what they know -- the sensations they feel in the womb.
Closer to birth, your baby sleeps 85 to 90 percent of the time, the same as a newborn.
On the Move
Around the ninth week of pregnancy, your baby starts making her first movements. Those movements are probably visible with an ultrasound, even though they can't be felt for several more weeks. By 13 weeks, your baby may be able to put a thumb in her mouth, although the sucking muscles aren't completely developed yet.
Although your baby's first muscle movements were involuntary, the first voluntary muscle movements occur around week 16. After this point, awake or asleep, your baby moves 50 times or more each hour, flexing and extending her body, moving her head, face, and limbs, and exploring her warm, wet home by touch. A baby may touch her face, touch one hand to the other hand, clasp her feet, touch her foot to her leg, or her hand to the umbilical cord. By week 37, your baby has developed enough coordination so that he or she can grasp with the fingers.
Along with these common movements, babies perform some odder activities, including licking the uterine wall and "walking" around the womb by pushing off with its feet.
Fetuses also react with motion to their mother's actions. For instance, ultrasounds have shown a fetus bouncing up and down when the mother laughs. Watching this on the screen, moms-to-be often laugh harder, and the fetus starts moving up and down even faster!
Second or third children may have more stretching room in the womb than first babies because a woman's uterus is bigger and the umbilical cord longer after her first pregnancy. These children usually get more motor experience in utero and tend to be more active infants.
By week 29, you should be feeling your baby move at least 10 times an hour.
Learning and Memory
Along with the ability to feel, see, and hear comes the capacity to learn and remember. For example, a fetus may be startled by a loud noise, but stops responding once the noise has been repeated several times.
Twins at 20 weeks' gestation can be seen developing certain gestures and habits that persist into their postnatal years. In one case, a brother and sister were seen playing cheek-to-cheek on either side of the dividing membrane. At one year of age, their favorite game was to take positions on opposite sides of a curtain, and begin to laugh and giggle as they touched each other and played through the curtain.
Studies have also shown a baby can feel and remember its mother's emotional state. An experiment in Australia revealed that unborn babies were participating in the emotional upset of their mothers who were watching a disturbing 20-minute segment of a movie. When the babies were reexposed to this film up to three months after birth, they still showed recognition of the earlier experience.
In the 1980s, psychology professor Anthony James DeCasper, PhD, and colleagues at the University of North Carolina at Greensboro performed a study with a feeding contraption that allows a baby to hear one set of sounds through headphones when it sucks faster, and to hear a different set of sounds when it sucks slower. This experiment revealed that within hours of birth, a baby already prefers its mother's voice to a stranger's, suggesting that it must have learned and remembered the voice from the womb. Newborns also preferred a story read to it repeatedly in the womb over a new one. And the same soft music that soothes them in utero soothes them again after birth.
Newborns can not only distinguish their mother's voice from a stranger's, but would rather hear Mom's voice, especially the way it sounds filtered through amniotic fluid rather than through air. They also prefer to hear Mom speaking in her native language than to hear her or someone else speaking in a foreign tongue.
Babies in the womb are probably reacting to the overall sound of voices and stories, not their actual words. But the conclusion is the same: the fetus can listen, learn, and remember at some level, and, as with most babies and children, he likes the comfort and reassurance of the familiar.
Sources: The Nemours Foundation; Association for Pre- & Perinatal Psychology and Health; Janet L. Hopson, "Fetal Psychology," Psychology Today, September-October 1998
Reviewed 11/02 by Elizabeth Stein, CNM
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