Timelines of pre-birth development can confuse those who don't realize that people measure gestation two different ways: from the beginning of the last menstrual period before the baby came into existence, and from the conception itself, usually around two weeks later. Most doctors will use the last-menstruation method, because they can't tell exactly on what day the baby was conceived. But the baby's life began mid-cycle, not at the start of mother's flow. The mother usually realizes she might be with child sometime later. Her next period is due two weeks after conception. Many periods start a week or even two weeks late even without pregnancy, leaving the mother to wonder for a while, but finally she gets the test or just assumes a child is growing inside her body.
- When Mom's next period is due, the baby has grown and used up a yolk sac, developed a placenta, formed the buds of several organs and traveled down the fallopian tube to the womb, where she has found a spot to settle in and taken up living there. She has a neural tube, a heart tube and a little developing circulatory system. Her brain is forming. Her heart makes its first beat but it will be a week before that heartbeat becomes regular. Nerve impulses shoot up and down the flexible spine, and the curve of her body whipe straight and curls again rapidly. Her little arms are starting to grow.
- Mom's period is now a week late and she is wondering whether she should get a pregnancy test. She has a child in her body who has a blood type that may be different from the mother's, a beating little heart, and the beginnings of a complete nervous system, nostrils, eyes with little lenses, and a spine longer than her torso, which looks like a tail but isn't a true tail, being continuous with the whole spine. She will grow along this pseudo-tail, as a tadpole does. In a week or so the "tail" will be all gone, she is growing so fast. She has a pancreas starting to process food energy, knees that work and intestines forming.
- Mom has gotten the test and it's positive. She thinks perhaps it's a false positive. She conceived five weeks ago and her period was due three weeks ago. Although she still has no symptoms or signs of pregnancy except the missed flow, she has the test results. She makes a doctor's appointment to have a blood test to be sure. Her child now has tiny blunt fingers and the buds of toes, functioning nerves, blood vessels and eyes, and is beginning to grow ears and a nose. She swims around in circles rapidly in the amniotic sac, flexing those elbows and knees. Her brain makes its own brain waves.
- After two months from the start of her last menses, the mother knows she is pregnant. She is far from showing yet, and still wears her usual clothes, but she is hungry when she isn't sick and sick when she isn't hungry. She begins to feel tender in the abdomen and breasts. Her daughter has grown every bone she will ever have and they are all connected, though some smaller ones are all cartilage. She has knuckles, reflexes, and most exciting of all, brain waves -- a sign of mental activity. The little girl is thinking now. What is she thinking about?
- It's been two-and-a-half months since Mama's period started, one-and-a-half since the missing one was expected, and two months on the calendar since the little one began her hidden existence. The mother is tired a lot, hot too often, feeling intense protective instincts that wear her out sometimes, and sore in a lot of places, but slightly euphoric sometimes. She still isn't visibly pregnant. She is sick in the morning and possibly other times. All the little one's organs are functioning, making her a fetus (Latin for child), rather than an embryo. Her eyes have color in the irises, she has hair, nails, and working kidneys and intestines. She can squint her eyes and pull her tongue back, not merely reflexively but on purpose. She can swallow. In her gums tooth buds are forming. She wraps a fist around an object -- including her own nose or ear -- that touches the palm of her hand. Her face looks distinctly human now, not the face of an undifferentiated embryo. No one who saw her 4D picture could think she was a chimpanzee or a gorilla for example. It's obvious what she is -- a little person.
- Another three weeks pass quickly while the mother searches for things the baby will need and buys herself a maternity outfit or two. Mother is now beginning to show, hungry but nauseated most of the time, and elated as often as not. She feels a kinship with every mother in the world. Her hair is thicker and her hips are spreading. If she loses this baby now, she will still be permanently physically changed and have the body of a mother, which is just what she is regardless of the pregnancy's result. As for her baby, she is breathing amniotic fluid in and out and sucking her thumb. She has a mature thyroid gland. Her liver breaks down wastes. She has vocal cords. Her pancreas is making insulin. Her neck is longer and her chin-on-chest crouch is gone, replaced by a dignified face-forward posture. Her swimming stroke has become fluid and coordinated. She flutters her fingers.
- It's already been another calendar month. Mommy is tired all the time. The nausea is over but a ferocious hunger has replaced it. Her body is working hard even when she appears at rest. She is showing if she wears tight clothing. Her ultrasound now makes it clear she is living with a little girl. The girl is grasping her umbilical cord and her own legs and hands, turning to face sources of noise, and learning how to kick her legs separately. She frowns, grimaces, tries to blink and hiccups. Her lungs have good news -- air sacs have formed! Alveoli, as they're known, enable the oxygen to enter the blood and the carbon dioxide to leave it through the lungs. She could almost breathe air, if she had any. All her lungs need now is surfactant to keep them open, more capillaries and more time to get a lot stronger.
- Mother is now obviously pregnant even in loose clothes, and wears maternity clothing. It's been 20 weeks, less than five months, since she conceived, about four months since she first suspected pregnancy. By this time her daughter could survive if born, depending on the neonatal care she could get and her own health at the time. She has very little room to swim. Now, when she kicks, Mom may feel it. The child has the same waking-sleeping cycles a newborn has, and patterns of activity and relaxation while awake. She has found a position she likes to sleep in. Her nerves would be frayed if she were born now, but the sheathes of myelin are coating them as we speak. Her head hair stands out from her all-over body hair, lanugo, and baby teeth under her gums are waiting to pop out, with a few grown-up teeth under them forming already. She has a uterus of her own. If she were a boy she'd have a prostate gland. Many babies born at this age live.
- In two more months, the mother's belly is round and beginning to stretch its skin. The house has a place for the baby to sleep. A pile of baby clothes lies on a drawer, donated by friends. Every day Mom wonders whether this will be it. If the little one comes out now, she won't need special care -- just regular newborn measures such as cutting the cord. It's too small in there to swim at all, or breathe much fluid. She really doesn't need to breathe much of the fluid at this point, since so much of it is her own urine or even her early bowel movements, which could damage her lungs. She would not be premature if born at this time. She probably weighs about five-and-a-half pounds. Mother conceived her nearly seven months ago and last started menstruating just over seven months ago. Mom suspected she was pregnant about six months ago.
- After another two months, the baby is just right -- a little younger and she might be skinnier than she ought to be, a little older and she might not get to move and breathe air when she needs to, and it would be too cramped. She produces a hormone that tells Mommy to push. Mommy sends a signal back to her that tells her to get upside down and aim for the open air. Together they work at birth for hour after hour. Soon the little girl is exhausted and freezing, the light is too bright for her, the air harsh on her skin. Nurses bundle her in soft flannel. She reaches for her mother, whom she recognizes by scent and voice from knowing her all her life. Mother holds her and names her.
That's the rough guide to life before birth. I posted it to take away the alien image of the unborn, the image of a stranger invading mother, and replace it with an honest, truthful image of the unborn child as a relation who has come quite by accident to live with her family. I want to foster respect and understanding among all age groups, including the youngest of us.