Up to 34 weeks
Thirty-four weeks after your last period, your baby is perfectly formed. All her proportions are exactly as you’d expect them to be at birth. She still has some maturing to do, though, and some more weight to gain before she’s ready to be born.
Your Baby’s Progress
Her organs are now almost fully mature, except for her lungs. These aren’t yet completely developed, although they’re making increasing quantities of surfactant, the fluid that will stop them from collapsing once she begins to breathe air. She makes strong movements that can be felt on the surface of your abdomen. Almost all babies born at this time survive.
Her skin, nails, and hair Her skin is now pink rather than red, because of the deposits of white fat underneath it. Fat deposits , build up under her skin to provide energy and regulate her body temperature after she’s born. The protective vernix caseosa that covers her skin is now very thick. Her fingernails now reach the ends of her fingers but her toenails are not yet fully grown. She may have quite a lot of hair on her head.
Her eyes Her irises can now dilate and contract. They’ll contract response to bright light, and also to allow her to focus, although she won’t need to develop this skill until after she’s born. She can close her eyelids, and she has begun to blink.
Her position Some babies take up the head-downward position about now, but there’s still plenty of time-most don’t engage until after 36 weeks. She may remain in the breech (bottomdown) position until birth, although most babies do turn on their own.
Her Support System
From this month the placenta layers may start to thin. To make estrogen, the placenta converts a testosterone-like hormone that’s made by your baby’s adrenal glands. By this month these glands are as big as those of an adolescent, and every day they produce 10 times as much hormone as an adult’s adrenal glands. They’ll shrink rapidly after birth.
The amniotic sac, or bag of waters, contains a large amount of fluid, most of which is the baby’s urine-she can produce as much as a pint (half a liter) of urine every day. Excess vernix caseosa, nutrients, and products necessary for the maturing of the her lungs are also in the amniotic sac. The umbilical cord is large, strong, and tough. A firm, gelatinous substance surrounds the blood vessels and prevents kinks or knots in the cord that could affect your baby’s blood supply.
Up to 30 weeks
Your baby’s now so big that when your or midwife examines you, they can check position and the way he’s lying. This is the month he can do a somersault.
Your Baby’s Progress
Great changes take place in your baby’s nervous system this month. His brain grows larger (to fit inside the skull it has to fold over and wrinkle up until it looks like a walnut), and his brain cells and nerve circuits are all fully linked and active.
Also, a protective fatty sheath begins to form around his nerve fibers, just as a similar sheath formed earlier around his spinal cord. This fatty sheath keeps developing until early adulthood. Thanks to this, nerve impulses can travel fasten and your baby is now able to cope with more complex type of learning and movement.
Your baby starts getting ready for birth. (If he were to be born prematurely at tlais stage, he’d have an excellent chance of survival. Even though he might have some breathing problems and difficulty in keeping himself warm, modern care facilities would help him thrive.) He’s beginning to gain some fat underneath his skin, which starts to smooth out, lose its wrinkles, and look more rounded. His coat of hairy lanugo may reduce to just a patch on his back and shoulders. The membranes that sealed and protected his eyes while they were growing will have fulfilled their function by the beginning of this month. His eyes are now fully formed and his eyelids have separated, allowing his eyes to open. He continues to develop the swallowing and sucking skills he’ll need as soon as he’s born.
His breathing - By now he’s developed his mature breathing rhythm, and the air sacs in his lungs start to get ready for the first breath he’ll take in the world outside your womb. The air sacs line themselves with a coating of special cells and a fluid (surfactant) that will prevent them from collapsing.
His movements - He’ll find he has less room to move around and may move less. He’ll wriggle uncomfortably if you’re in a position that doesn’t feel good to him.
Orientation - During his weeks of “gymnastics practice,” your baby has done more than increase his muscle tone-he’s developed the ability to position himself in space. He’ll probably continue to lie with his head upward during this month, although if he’s maturing fast he may turn upside down and settle into place for delivery (engage) earlier than usual. This is more common in first babies. Babies can continue turning up to 36 weeks.