Her voice comes to him like a stream of music, particles of sound from a world outside his own. He has awakened from a sleep and from a dream he won't remember, and feels swaddled by sound -- not just the voice, which pleases him, but the decisive beating of his mother's heart, the grumble of her intestines, the murmur of her lungs as they balloon and then deflate. The light is dim inside the womb. Blood gurgles as it washes by. He feels the weight of his mother's hand pressing in, toward his knee, and he presses his knee out toward it, as if to say, Yes, I am here.
Thirty-eight weeks ago he was nothing but one cell. One cell that then divided into the stuff of tissues, organs, bones, and hormones, each cell finding its place in the growing cluster by heeding the instructions inscribed in its genes. Some cells sloughed off and others settled in for life -- folding and migrating until, for instance, a miniature tube became his pumping, robust heart. Now, transparent nails cap the tips of his fingers and his toes. Billions of neurons are bundled in his brain. There are creases on the bottoms of his feet, and on the sides of his head are the fleshy blooms of his ears.
Now that he has a mouth and hand, he sucks his thumb. He squints toward the placenta through the amniotic fluid in which he floats. Attached to the back wall of his mother's uterus, the placenta utterly encircles him, anchoring him in with the ropy umbilical cord. The placenta is the only organ he'll discard upon his birth. An ingenious collaboration, composed partly of his cells and partly of his mother's, it has served him these last many months as lungs, liver, kidney, endocrine glands, commissary, and telephone. How has he been getting his oxygen and blood? Through the placenta. Where has he been sending his waste? Back to the placenta. From where have his glucose, amino acids, water, fats, mineral ions, and vitamins come? The placenta. By what means has he already initiated the processes of his own birth? By sending a squirt of hormone to the placenta, of course.
For indeed the time has come. There's enough fat on his body now to help him make the transition to what will be a far cooler, drier environment. Enough neural pathways have been established between his sense organs and his brain. He has shed his lanugo (the fine hairs that have covered his body for many weeks) as well as his vernix caseosa (the waxy white coating that has protectively sheathed his skin during his long incubation), and then swallowed both; they'll ooze away from him after birth, with his first bowel movement. His bloodstream has been fortified with his mother's immunoglobin proteins. And he's ingesting the salty, growth factor-enriched amniotic fluid that he floats in -- thereby helping the maturation of his digestive system.
For weeks now, he has been practicing breathing -- exercising the muscle fibers of his diaphragm, strengthening the nerve connections between his respiratory center and his brain, ensuring that his lungs will have the stuff it takes to expand and ventilate when they finally meet air. And, just to ensure that all systems will indeed be go, he has lately given himself over to the stuff of sleep, napping as much as 95 percent of the time. He's been spending much of that naptime in rapid eye movement (REM) sleep, which has increased his heart rate, fluttered his eyes, quickened his pulse, sparked the release and receipt of electromagnetic pulses. This has been integral to the development of his brain -- pushing the mass of bundled nerves, cells, and connections to sort themselves out in time for life outside the womb.
Now the fetus hears a low-frequency sound -- the voice of his father. Soon thereafter, the voice of his mother wafts in. He feels his body swaying, and senses that his own oxygen level has started to decline, for his mother is pacing again, exerting herself and, therefore, him. His body responds as it always does at times like these -- channeling the oxygen-rich blood to his brain and other critical organs, protecting them above all else.
Upside down and snug in his mother's womb, the fetus is aware that his mother's abdomen is tightening around him. Small, painless contractions that are a mere precursor of what's soon to come. "The baby comes when the baby's ready" may be folk wisdom, but it is also a fact, and this fetus -- fully developed, with no more space to stretch and grow -- is definitely ready for life outside.
Life On the Outside
A few days ago, his brain's hypothalamus sent a message to his pituitary gland. His pituitary, in turn, sent a signal (a small dose of the chemical adrenocorticotropin, or ACTH) to his adrenal glands, which subsequently played their part by releasing a stress hormone, called cortisol, through the umbilical cord to the placenta. There, it has begun to promote the production of estrogen, suppressing the manufacture of progesterone and, at the same time, releasing enzymes that are capable of converting progesterone into estrogen. Thus, without raising the suspicions of his mother, the fetus -- as seemingly helpless as he is -- has triggered the processes of his birth.
All throughout her pregnancy, his mother's abdominal muscles have been held in stasis by the predominance of progesterone over estrogen. Enough progesterone has kept her body from rejecting the foreign object of her fetus; the right amount of estrogen, on the other hand, has made mild contractions possible, keeping the abdominal muscle toned.
Now that contractions are required to bring the pregnancy to a close, the hormonal ratio must begin to shift in favor of estrogen. The softening and dilation of the cervix is reliant on estrogen, as is the production of proteins that encourage contractions. The ability of the mother's blood to coagulate during the birthing process depends on estrogen; so does the production of prostaglandin and oxytocin receptors. Without these, vaginal childbirth would be impossible, for it's only after estrogen makes the mother's uterus more suspectible to oxytocin -- and oxytocin and prostaglandin then stimulate the contractions of smooth muscles in the uterine wall -- that the whole choreography of labor can genuinely begin.
To get the contractions moving at some meaningful tempo, what's needed is a dose of oxytocin, whose production is a collaborative effort: it's released by the pituitary glands of both the mother and the fetus. The release of the oxytocin promotes further hormonal releases from the adrenal and pituitary glands of the fetus. Mother and child have officially entered the first stage of labor.
Contractions will start coming every 15 to 20 minutes or so now, each lasting 30 to 60 seconds. For the mother, there's pressure and pain. For the fetus, there's the sensation of being squeezed. He hears voices outside himself, feels the rock and walk of his mother's pelvis. As labor progresses and the cervix starts dilating, contractions come more forcefully, more quickly, bring more pain to the mother. With his own head, the fetus helps the process along -- stretching his mother's cervix until it initiates a new cascade of nerve impulses that travel up the mother's spine to her pituitary gland, which answers with the release of more oxytocin. This further stimulates the contractions. Inside, the fetus feels the squeeze and release of the muscular chamber that's housed him these many months.
With every contraction, the uterus shortens and closes, inching the fetus farther down. With every contraction, the cervix widens. If things seemed tight before, they're nothing short of crowded now. The contractions are coming far more often, and the fetus is dimly aware of an array of new sounds outside the womb. He hears the groan of his mother, the soothing voice of his father. Now he is squeezed tightly; it's not pain he feels, but pressure. The uterine muscles clamp down on his head with such persuasion that he begins to release the thyroid hormones and adrenaline that his body instinctively knows it will need to adjust to the cooler temperatures in the outside world.
The pressure from the contractions, as well as the rising concentration of prostaglandins, also protect him from a serious danger: the temptation to breathe. Breathing before his head is completely free of the birth canal would mean taking in fluids and risking pneumonia, so the fetus obeys the blueprint in his genomes that instruct him to wait until the world can hear him cry. It might sound easy, but his oxygen supply is getting thin. His umbilical cord, with its many vessels supplying oxygen-rich blood, is stretching. His mother's blood vessels are squeezed. The placenta is starting to tear away from the anchor of her uterus. But he mustn't yet breathe.
All of a sudden something breaks. he feels the amniotic fluid trickle, then rush past him. Just below his head, the cervix is at last fully dilated. He feels his head push through a narrow channel, caught in the vice of a contraction. With the cervix fully dilated, he can now push through the birth canal, but it's not a journey even this world-ready fetus could make were it not for his own soft skull, which deforms in the narrow passage. Still, no pain for the fetus. Just pressure.
It seems to go on for an eternity. The umbilical cord is stretched thin. There's hardly any oxygen in his blood. The amniotic fluid is being squeezed from his lungs. His body fights fatigue.
Suddenly, there it is: A cold, bright, shouting light -- dry air! Sound turned up to a whole new level. Slippery hands upon his head. A clamp on his umbilical cord. He wails. Instinctively, he turns 90 degrees in the birth canal, and trusts the hands in this new world to pull his naked body free.
The fetus' holler is that very first breath he's practiced for. His lungs draw in the air and its air sacs open. The oxygen relaxes the walls of his lungs' blood vessels, causing them to dilate. Whereas in the womb the fetus' blood bypassed his own lungs and was shunted off to be oxygenated by his mother's, now the shunts close forever, and his blood begins to find its way into his lungs. There, it is oxygenated, and rushed into his arteries via his heart.
The world the baby has entered is strange and new. There's five times more oxygen available now than there was ever before, and the rush of its life-giving molecules stimulates his nerve cells. He still has a lot to master, for his umbilical cord has been cut and his placenta -- surrogate lung, kidney, protectorate -- is no longer a part of his life. Now his nutrients must come from milk. Now his kidneys must take charge of balancing his bodily fluids. But before he's given much of a chance to grasp the skills he'll need, he's given (and isn't this just like real life?) an exam -- an Apgar test -- which assesses his heart rate, respiratory effort, color, muscle tone, and reflexes. Then he's carried beneath the harsh lights, through the dry air, toward a new destination.
A sweet voice he recognizes speaks to him, and a second voice whispers in his ear -- his father. Who knows what the proud, encouraging sound waves mean, but they play like music to his ears. He nuzzles close in his mother's arms.
Beth Kephart's A Slant of Sun: One Child's Courage was a 1998 National Book Award finalist.