The Freaky Changes Your Baby Goes Through During the Second Trimester

The second trimester of pregnancy is often referred to as the dream or honeymoon trimester. During weeks 13-28 of pregnancy, this is usually the time the woman feels best during her pregnancy. The morning, or all day sickness in many cases, finally subsides, energy increases, and expectant moms no longer feel like a giant sack of exhausted garbage. The baby bump has just popped, and most pregnant women aren’t uncomfortable yet from carrying around a near-full term, back-breaking bundle of joy. They might also be excited that they can finally go public with their big news!

Many women spend a lot of time looking up questions about why they’re so tired and nauseous, along with quick fix cures in the first few months of pregnancy, and for solutions to problems like heartburn, indigestion, and sciatica in late pregnancy. A lot of “what to expect” information focuses on mom, her health, and what she can be doing to help with the growth and development of her little bean.

Sure, there are sites that expectant parents explore that highlight what fruit or veggie their little baby is comparable in size to from week one all the way to week 40, but what about the other stuff going on with that tiny nugget? What are the freakiest changes that your little peanut goes through during the second trimester, a time when they morph from the size of a nectarine to the size of an ear of corn all while mom is generally feeling pretty darn good?

7 Feed Me Seymour!

Those ketchup chips you’ve been stone cold munching by the bag-full for weeks now, your baby can actually taste them from inside the womb. During the second trimester, the baby starts swallowing a little bit of mom’s amniotic fluid every day and by week 21 they’re swallowing several ounces of amniotic fluid each day. This allows baby to gain nutrition and hydration as well as practice swallowing and digesting in preparation for life on the outside.

Baby’s taste buds are developing this trimester, although the food won’t taste quite as flavourful to Junior as it is to mom since so much of taste depends on smell. Some babies are known to hiccup in response to mom eating spicy food.

What Does Research Say?

Researchers have found that babies whose mothers ate specific foods (tastes) while they were in utero were more likely to eat food with similar taste after birth. So food taste variety is the spice of life, hiccup!

6 Baby can Pee (Kind of)

Week 13 marks when baby begins to form urine and they discharge it regularly into the amniotic fluid. This also means that they are regularly consuming their own urine as they swallow amniotic fluid. Some joke that this a sneak peek into the world of the disgusting things infants are capable of producing and doing. A little bit gross, a little bit cool.

At around 18 weeks into gestation baby will develop vernix caseosa, a waxy, white cheese-like substance on their skin. This coating acts as skin barrier, protecting them from the drying effects of submersion in amniotic fluid. This gouda-like blanket is made of sebum (oil on the skin) and dead skin cells. It is excreted from the baby’s sebaceous glands.

Will it Go Away?

Vernix caseosa begins to disappear right before birth. Some babies, often those born prematurely, still have a great deal of cheesy goodness covering their skin at birth. This is removed shortly after birth during baby’s first bath. The rest is reabsorbed into baby’s skin. 

5 A Warm and Fuzzy Coat

In addition to the protection properties of vernix caseosa baby will also develop a thin downy coat of hair all over their body that is called lanugo. It appears at around five months into pregnancy, covers most of baby’s body and is usually shed during the last month “on the inside”.

Lanugo can cover all skin except for the lips, palms of the hands and pads of the feet, sides of fingers and toes, nails and glans of the penis or the labia minora and majora. If a baby is born with lanugo it sheds on its own, usually about three to four months after birth.

A Cultural Perspective

Some cultures have remedies to speed up the shedding of the fine hair such as applying a paste of wheat flour, combined with raw milk and rose water to the skin, however, these home remedies or extensive washing and scrubbing won’t necessarily work and can irritate a young infant’s skin. There is no medical reason to try to speed up this process.

4 Sex Reveal

Even though the sex of baby is decided at the moment when the egg and sperm meet, it takes considerable time for the external organs to match up with the internal chromosomes. This means that it’s not until the second trimester when parents are often able to find out the sex of their wee sprout via ultrasound. This is usually possible around week 18-20.

Baby boys and girls can look very similar in an ultrasound until around 14 weeks. 19 weeks into gestation girl babies begin to form their uterus and vagina. By 20 weeks a baby girl will have 3, 000, 000 eggs in her ovaries.

Breathing Underwater

The little mermaid or merman, as whatever the case may be, is “breathing” underwater. While baby receives oxygen care of the umbilical cord in the womb, at around 27 weeks, on the cusp of the third trimester, practice breathing begins. The teeny one’s lungs begin to expand and compress from contractions in mom’s chest muscles and diaphragm. These contractions develop the actual muscles and motor circuits required for actual breathing once baby is born. 

3 Bodily Movements

During the second trimester, your baby’s eyes will move locations. In the first trimester they are situated on the sides of the head, similar to the placement of predatory monocular eye placement. During week 14 they will move to the front of the head for binocular vision placement, where they’ll stay. By week 25 the eye will contain rods and cones, with over 100 million rods and 7 million cones per eye. At 26 weeks baby can actually produce tears and open their eyes.

A baby can see after week 26 when its eyes are no longer fused shut and they are able to blink. Unfortunately, there isn’t much in terms of the view. What they are seeing can be compared to what we would see on a foggy day, amniotic fluid is the fog, looking into a dark cave – AKA the womb.


Recent evidence suggests that mom getting plenty of sunshine can help the little one develop better eyesight. Some photons of light can actually make it through the skin into the womb when pregnant moms are standing in the sunshine. 

2 I’m Listening

At around 16 weeks the tiny bones that make up little bean’s ears will grow, at 18 weeks to stick out of their head. At this point, your munchkin will begin to hear and respond to a number of sounds your body makes, including your heartbeat, your blood running through your veins, and even your stomach grumbling. By week 24 they will be able to respond to voices and noises, and soon after will be able to recognize familiar voices, like mom’s. Research also suggests that if you repeatedly play a piece of music or melodies from in utero baby will be able to recall it for up to four months after birth. No wonder my kids are so awesome at dancing and singing to Abba at the tops of their lungs.

While it’s believed that fingerprints begin forming during the 10th week of gestation they aren’t permanent until week 17. Prints form with a number of environmental factors playing a key role. The exact position of the child at the particular moment, including the precise composition of the amniotic fluid surrounding their fingers as they touch various places inside the womb will decide each individual ridge that is formed. So many parents have it right: their baby is as unique as a snowflake.

Book Em Danno!

The entire development process for fingerprints is so unique that in the entire course of human history, there is essentially no chance that the same fingerprint pattern will form twice. Even identical twins will not have the same fingerprints as one another. Prints appear on the hands first, followed by the feet/toes. By week 26 baby will have fingernails and toenails as well.

1 Bone-In or Boneless?

Until week 15 of pregnancy the baby will not have bones, but just cartilage. At this point the 300 bones that the baby will have at birth, start to develop. These bones become visible on ultrasound imaging just a few weeks later. Baby’s skull will remain soft and flexible through the entire pregnancy, to allow for “soft spots” that help baby pass through the birth canal.

Many parents breathe a small sigh of relief after week 24 into pregnancy. After week 24 the fetus or baby becomes viable, meaning that if born now, prematurely, the baby will have a reasonable chance of survival. Each day after this week, the chances of survival increase along with risks for complications. Technology has also meant that, in very recent years, a small number of babies have been able to survive at 22 weeks without major health problems, helped by extensive, state of the art medical intervention.

Point of Viability

While mom seems to get a bit of a break from the symptoms associated with early and late pregnancy in the second trimester, little Bud (Baby Undetermined) is undergoing a complete metamorphosis! So moms in your second trimester, stay up past ten, enjoy those ketchup chips without heartburn knowing that a whole lot of strange, freaky, amazing stuff is going on as your baby morphs from the size of a lemon to an ear of corn! Oh yeah, and when your kids are older, you can tell them all about the time they drank their own pee.    

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