Your Growing Baby: The Second Trimester
The second trimester encompasses weeks 14 through 26. During this stage, the fetus lessens its dependence upon the mother, becomes more active and forms many outward characteristics that distinguish it as a unique individual. It grows from about 6 inches to nearly a foot. Its weight increases from approximately 4 ounces to 2 ¼ pounds.
By the 14th through the 16th weeks, the fetus is well on its way to becoming its own person. In fact, fingerprints have formed on its tiny fingers, giving it its own identity. Its first attempts at sucking are rewarded with mouthfuls of amniotic fluid. Its head begins sprouting fine strands of hair known as lanugo. Beneath the transparent skin of the fetus, the intestinal tract is busy making meconium, a gooey substance that will be expelled as a bowel movement soon after the baby is born. Sweat glands have formed. Meanwhile, the pancreas and liver have begun secreting fluids. While mom cannot see these developments, she can certainly feel more of a presence in her tummy. Those flutters she feels indicate that the fetus is becoming more active. Furthermore, her expanding abdomen is a sure sign that the fetus is growing.
Around weeks 17 through 20, mom may start thinking that the little being inside her measures more than 8 inches and weighs more than 12 ounces, for its movements have become more pronounced. Even more exciting, the fetal heartbeat is now so strong that a stethoscope can detect it. With the forming of eyebrows and eyelashes, the face becomes more defined. Tiny nails now adorn the toes and fingers. The skin undergoes many changes during this phase, such as developing a white pasty coating called vernix, a protection from amniotic fluid.
If seen on an ultrasound between weeks 21 and 23, the fetus will look like a newborn baby, complete with chubby cheeks and limbs. The eyes will seem ready to recognize their mom. The skin will have lost much of its transparency. Lanugo, once confined to the head, will now form a downy layer across entire body. Internally, important growth is underway, particularly with the pancreas and liver, which are becoming more functional. In the next few weeks, the fetus will grow just a few inches in length, from about 10-11 to 14 inches, but it will double in weight, from approximately 1 pound to slightly more than 2 pounds.
No doubt, mom will feel the difference. Indeed, weeks 24 through 26 mark a thrilling stage, as mother and fetus become more in touch with each other. If mom hits a bump while she is driving, the fetus may show that its startle reflex is now working by lurching. Throughout the day, mom will notice periods of calm within her tummy, as her baby-to-be catches a nap. The fetus may announce it is awake by giving a little kick, followed by a burst of activity. Like clockwork, the fetus’s internal mechanisms are becoming finely tuned. Mom will come to know the fetus’s cycle of waking and sleeping as well as her own.
Towards the end of the second trimester, the brain, lungs and nervous system have developed rapidly. Now, on the verge of the third trimester, they are capable of sustaining life. In fact, babies delivered during weeks 24 through 26 could survive, though not without the help of life-support devices.
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