Second Trimester

— Dana

Since this is my first pregnancy, I find all the information very fascinating…


• Your infant is about 2.91 inches (7.4cm) and weighs around 0.81 ounce (23gm) – This is about the same weight as 4 quarters.
• If you could peek in again you may spot your baby as he begins to practice inhaling and exhaling movements.
• Eyes and ears continue to move and develop.
• Baby’s neck is getting longer, and the chin no longer is resting on his chest.
• Her hands are becoming more functional – Your baby may find it comforting to start playing with her fist.
• At this point all nourishment is received from the placenta.


• Thyroid gland has matured and your baby begins producing hormones which will be used throughout his or her life.
• In boys, the prostate gland develops.
• In girls, the ovaries move from the abdomen to the pelvis.
• Your little one may have learned to suck his thumb by this point!
• Your child’s bones are getting harder and stronger by the day!
• Your baby’s skin is very transparent still.
• Lanugo (very fine hair) covers the baby’s body and will continue to grow until 26 weeks gestational age – Generally this will be shed prior to birth. Its purpose is to help protect baby’s skin while in all that water!
• Your baby is 3.42 inches (8.7cm) long and weighs about 1.52 ounces (43 grams) – approximately the weight of a letter!


• You may begin to feel some fluttering movements as baby kicks, flails, twists and turns (but don’t panic if you don’t yet). She can also grasp, squint, frown, grimace and maybe suck it’s thumb!
• Your baby’s legs have grown longer than the arms and the body is now longer than the head.
• You’ll be happy to note that it is moving those arms and legs often!
• It’s skin is very thin — so thin blood vessel are visible. It’s covered by a fine, soft layer of hair called lanugo. Lanugo comes from a Latin word meaning “down.” This hair is thought to help insulate your little baby.
• The three tiny bones in it’s middle ear have begun to harden. The auditory centers in your baby’s brain haven’t developed yet, so they might not really understand what you’re saying but it’s hearing capacity is in the process of developing.
• Fingernails and toenails are growing.
• Eyebrows are beginning to grow and even the hair on it’s head is sprouting. It will probably change color and texture after birth.
• All this and your little one is an amazing 3.98 inches (10.1cm) long and may weigh 2.47 ounces (70gm).


• Fat begins to form underneath skin, providing your baby with insulation for the coming months.
• Did you know that both the baby and placenta are about the same size now?
• Your little one has reached 4.57 inches (11.6cm) and approximately 3.53 ounces (100gm).
• It’s head and neck are held straighter now.
• This is a week of “mights!” You might hear the tiny thumps of his heartbeat with an external monitor now. The genitals are developed sufficiently that an experienced sonographer might be able to determine if your baby is a boy or a girl.
• The heart is pumping as much as 6 gallons of blood a day and beats at a rate about double your heart rate.
• If you could take a peek inside, you would witness your child’s reflexes in action! (Sucking, swallowing and blinking are now evident.) It is probably even hiccuping even though you don’t feel it yet!
• Your baby has learned to breathe! This is apparent from the regular movements of it’s chest. Isn’t it amazing that they are able to breathe “underwater,” inhaling and exhaling small amounts of amniotic fluid? These actions help the lungs to develop and grow.


• By week 17, your baby weighs about 4.97 ounces (140gm) and is 5.12 inches (13cm) long.
• He or she has a much more normal “human” appearance now. They hold their head more erect and it’s body and limbs are longer in proportion to it’s head.
• Pads are forming on it’s tiny fingertips and toes. Soon those individual swirls and whorls will be apparent.
• It’s eyes are looking forward now, but they are still firmly closed.
• Meconium (composed of products of cell loss, digestive secretion and swallowed amniotic fluid), is accumulating in the bowel. This black gooey substance will become your baby’s first poop!
• The umbilical cord is growing thicker and stronger and continues to rush blood and nutrients to your growing baby.
• If your child is male the prostate begins to develop.
• It’s skeleton is transforming from cartilage to bone. The bones remain flexible to make the journey through the birth canal easier.


• Vernix (a white cheese-like protective material) forms on baby’s skin with the lanugo (soft, lightly pigmented hair covering the body and limbs); both serving to protect your baby’s skin during the months in water.
• Your placenta continues to grow and nourish the baby. Don’t forget those prenatal vitamins!
• Tiny air sacs called alveoli begin to form in lungs. They’ll be putting those lungs to good use in just a few months!
• It’s vocal chords are formed. They can go through the motions of crying, but without air they don’t make a sound.
• Features of your baby’s heart, including ventricles and chambers, should be visible during an ultrasound.
• Your baby measures about 5.59 inches (14.2cm) this week and weighs about 6.7 ounces (190gm).


• Your baby has the same awake and sleep patterns of a newborn. They have a favorite position for sleep and recognizable active and rest periods.
• Throughout your baby’s body, nerves are being coated with a fatty substance called myelin, which insulates the nerves so that impulses can flow smoothly.
• Scalp hair becomes apparent this week. It has sprouted and continues to grow.
• The milk teeth buds have already developed and over the next few days the buds for the permanent teeth will begin to form behind the milk teeth.
• If baby is female the uterus starts to develop. If you’re having a girl, the vagina, uterus, and fallopian tubes are in place.
• If it’s a boy, the genitals are distinct and recognizable.
• Your baby is swallowing amniotic fluid and his or her kidneys are making urine.
• Your little one’s size is around 6.02 inches (15.3cm) and 8.47 ounces (240gm).


• You’re half way there!
• The rapid growth stage is about over. While things have slowed down, this next stage is vital to survival.
• The baby’s heart grows stronger. Find a quiet place, lay flat on your back. Locate your own heartbeat by finding your pulse. Next lay your hand on your belly. You may be able to distinguish the two heartbeats!
• It’s legs are reaching their relative size. With the increase muscle develop occurring as well, you will start feeling much more than tiny flutter kicks soon!
• Immunities are being transferred from you to your baby now. These immune cells will protect it from viruses you’ve already had for up to six months after birth!
• The nerve cells for taste, smell, hearing, seeing, and touch are now developing in specialized areas of the brain. Production slows down as existing nerve cells grow larger and make more complex connections.
• Your baby may startle in reaction to loud sounds. Amazingly, it can actually hear noises outside of the womb. Familiar voices, music, and sounds that baby becomes accustomed to during her development stages often are calming after birth.
• If your baby is a girl, her uterus is continuing to develop. She has approximately six million eggs in her ovaries. About one million will remain at birth.
• Baby is about 6.46 inches (16.4cm) and weighs around 10.58 ounces (300g).


• White blood cells are under production. Leukocytes (or white blood cells) form our body’s defense sytems. They help fight infections and diseases.
• Your little one’s skin has changed from translucent to become more opaque.
• Your infant’s tongue is fully formed. If you were able to peek you might catch your son or daughter practicing giving you a raspberry!
• If your baby is a girl, her womb and vagina are formed. Unlike males, females have a limited supply of eggs in their lifetime. At this point your daughter will have 6 million eggs. This amount decreases to approximately one million by birth.
• Baby swallows more this week. After your baby takes in amniotic fluid, it’s body absorbs the water in the liquid and moves the rest into the large bowel. This is good practice for his digestive system!
• Wake and sleep periods become more consistent. Some research suggests that a baby sets it’s internal clock to match the outside world’s even before birth! Your eating and sleeping habits as well levels of light and noise serve as her signals.
• Length is now measured crown to heel.
• Baby measures about 10.51 inches (26.7cm) and weighs nearly 12.7 ounces (360g).


• Your baby weighs close to a pound at this point!
• Your baby can now hear your conversations more clearly than before!. When you talk, read, or sing, expect her to hear you. Studies have found that newborns will suck more vigorously when read to from a book they heard frequently in utero.
• Eyelids and eyebrows are fully formed.
• Fingernails have grown to the end of the fingers.
• Be prepared for all those “Why” questions coming! Your baby’s brain has entered a stage of rapid growth, especially in what’s called the germinal matrix. This structure deep in the middle of the brain serves as a kind of factory for brain cells and disappears shortly before birth. But the brain’s amazing expansion program continues until around the fifth birthday.
• With some help from mom, baby’s liver is starting to break down bilirubin, a substance produced by red blood cells.
• If your baby is male his testes begin their descent to the scrotum. Primitive sperm have formed and he is producing testosterone.
• Length is 10.94 inches (27.8cm); weight is nearly 1 pound (430gm).


• Proportions of the body are now quite similar to a newborn although thinner since it hasn’t begun to form body fat.
• Bones located in the middle ear have harden.
• Your baby is able to hear. (Dads, did you know: low-frequency sounds mimicking a male voice penetrate the abdomen and uterine wall better than the higher frequencies of the female voice?)
• The eyes are formed, though the iris still lacks pigmentation.
• The pancreas, essential in the production of hormones, is developing steadily. It has begun producing insulin, important for the breakdown of sugars.
• If born now, your baby has a 15% chance of survival, and it’s odds go up with each passing day.
• The average baby at this stage weighs 1.1 pound (501gm) and is 11.38 inches (28.9cm) long.


• Bring on the bulk! Baby gains about 6 ounces this week. The weight is in muscle, bone mass and organs.
• It’s body begins to fill out with his appearance increasingly becoming more like a newborn.
• Taste buds begin to form. If mom drinks something strange or bitter, baby may be observed showing it’s distaste.
• Little creases have appeared on it’s palms. The muscular coordination of it’s hands have improved as it sucks it’s thumb.
• Over the next seven days the sweat glands will be forming in the skin.
• Their lungs are developing “branches” of the respiratory “tree” and cells that produce surfactant, a substance that helps the air sacs inflate easily.
• This week your baby is officially considered viable.
• Baby weighs 1.3 pound (600gm) and is 11.8 inches (30cm) long — almost the length of a ruler!


• The structures of the spine begin to form — joints, ligaments and rings. These will protect the all important spinal cord which serves as the information transmitter for your child’s body.
• Blood vessels of the lungs develop.
• Your baby’s nostrils begin to open. There is a study out of Belfast that suggests babies at this stage have the capability of scent preferences!
• The nerves around the mouth and lip area are showing more sensitivity now. When the baby is rooting for food later on, these will be valuable!
• It’s swallowing reflexes are developing.
• Dexterity is improving. Your baby can make a fist and would clasp objects placed in palm.
• Your child has now obtained an approximate length of 13.6 inches (34.6cm) and weighs 1.46 pound (660gm).


• Your baby may weigh about two pounds now (average is 1.7 pound, 760gm) and is 14 inches (35.6cm) in length
• 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, 33 rings, and some 1,000 ligaments.
• Air sacs in the lungs form now.
• Lungs begin to secrete a greasy substance called surfactant. Without surfactant the fetal lungs would stick together and couldn’t expand after the baby is born.
• Although they’ve been sealed shut for the last few months, your baby’s eyes are opening and beginning to blink this week. Depending on ethnicity, some babies will be born with blue or gray-blue eyes (which may change color in the first 6 months of life) and some will be born with brown or dark eyes.
• Retinas begin to form.
• Brain wave activity for hearing and sight begins to be detectable.
• Fetal brain scans show response to touch. If you shine a light on your abdomen, your baby will turn his head, which according to researchers, mean it’s optic nerve is working.