Fetal Development Weeks 22 Through 26
See what's happening with your baby in the sixth month of your pregnancy.
Your baby is covered in sticky white goo. But that's entirely normal! This waxy gunk is called vernix caseosa, and it protects the skin from the watery amniotic fluid. Without the vernix, your baby would be as wrinkled as a prune. A product of the sebaceous glands (which will produce skin-oils later in life), the vernix also protects your baby from skin infections and makes her slippery for an easier trip through the birth canal. Some of the vernix dissolves into the amniotic fluid toward the end of the pregnancy, and the rest will be washed or wiped off in the birthing room after your little one makes his big debut.
If the baby is male, his testes, which have been tucked up inside the pelvis, begin to descend into the scrotum this week. Primitive sperm have already formed in the tiny squiggling passages of the testes, called the seminal vesicles. This little guy is already producing testosterone!
Sing, shout, laugh -- your baby can hear you! As of the end of this week, her hearing will be well established, thanks to the bones of her inner ear, which have hardened and are able to detect sound vibrations. She can pick up noises from outside the womb and from within -- the rush of your bloodstream, the thumping of your heart, and even the gurgling of your stomach. At birth, baby recognizes mom's voice by its frequencies and patterns, so don't be shy about talking to her often during her time in utero. And dads should chime in, too. In fact, research shows that low-frequency sounds mimicking a male voice penetrate the abdomen and uterine wall better than the higher frequencies of the female voice.
The baby is taking on the shape of a full-term baby at this point, but her bones and organs are visible underneath a thin layer of translucent reddish-pink skin.
At this point in pregnancy, baby's lungs are getting ready for breathing. Airway passages form tubes in order to take in and expel air. Blood vessels and air sacs develop in the lungs; they will eventually exchange oxygen and circulate it to all parts of her body. The cells in the fetal lungs begin to produce surfactant, a substance that keeps the sacs from sticking together. All of this means that your baby's lungs have developed enough so that, conceivably, your little one could survive outside the womb.
Still, your baby still has a lot of growing to do. Optimally, he will stay put until what is considered full term at the end of the 37th week.
The tooth fairy is hovering over your baby this week, as baby's permanent, "grown-up" teeth are developing in buds high inside his gums. But the fairy will have a long wait -- these adult teeth won't come in until the baby teeth (also called primary teeth) start to fall out around age six. Meanwhile, nerves around the mouth and lip area are showing more sensitivity now, preparing baby for that all-important task of finding a nipple and sucking down food. His swallowing reflexes are developing, too, but for now all he's taking in is amniotic fluid. His kidneys process the liquid, and it exits his body as baby's urine.
That crucial lifeline, the umbilical cord, is thick and resilient now. A single vein and two arteries run through it, encased in a firm gelatinous substance that prevents kinking and knotting and may regulate the bloodflow between placenta and baby.
Feel like your baby is bouncing off the walls? It's no wonder -- her living quarters are getting pretty snug these days. Measuring from head to toe, she is, on average, over a foot tall and very likely weighs in at over two pounds. Most of this gain has been in bone and tissue -- she is still quite slender, with very little body fat. Fat will be laid on during the third trimester, the better to keep her warm when she leaves the climate-controlled comfort of your womb.
To support the fetus's growing body, the spine is getting stronger and more supple. Though no longer than the span of the average adult hand, it is now made up of 150 joints and some 1,000 ligaments.
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