Behavior Patterns in the Womb

Your baby has a personality of its own at birth, but did you know that behavioral patterns can also be tracked during gestation? Prenatal development not only consists of the physical process of organ and skeletal development and growth, but by the age of 14 weeks, the developing embryo is already capable of rudimentary forms of behavior.

The tiny embryo can swallow and digest amniotic fluid, urinate and wiggle its fingers. It can frown and kick in response to external noises and movement. By the end of the third month of gestation, the embryo can squint, make a fist, and suck, all in response to external stimuli.

Thumb sucking is also present by the end of the third trimester. By 24 weeks, the fetus can hear sounds readily. The eyelids freely open and shut, possibly in response to subtle changes in light patterns inside the womb, which is mostly dark.

By 28 weeks, the fetus has developed a sophisticated pattern of sleeping, placid wakefulness and alert activity, all of which cycle regularly throughout the baby’s “day.” Of course, your baby’s “day” doesn’t coincide with yours, which explains the frequent occurrence of fetal kicking just as its mother is trying to get some sleep.

Although 95 percent of newborns are totally healthy at birth, during critical periods of gestation, viruses and numerous legal and illegal drugs can have a detrimental effect on the developing embryo. Brain damage, for example, is most prevalent from weeks 3-5 of gestation. Heart defects occur from weeks 3-6. Arm, leg and eye deformities generally occur between weeks 4-8. The critical period for ear problems and deafness is a slightly longer period, spanning the first 4-9 weeks of pregnancy. Cleft palate, or the failure of the oral cleft to properly fuse, occurs during weeks 6-9.

Clearly it is the first trimester that carries the greatest risk for defects to occur. This is the reason that miscarriages primarily occur in this period. Unfortunately it is also the time that the mother is least likely to be aware of her pregnancy, and is the reason why all women who are intending to become pregnant are advised to taper off drugs and take supplements prior to getting pregnant.

In coming articles, we will look at mental development through the ages.

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