It is amazing enough knowing that a new little tiny human develops in just 9 months. It’s remarkable to know that from a little egg inside the womb, a fully fledged neonate baby is ready to enter the world. It may seem like a long time, but 9 months is quite short considering just how much development takes place.
While it is easy to settle for being satisfied with ultrasounds and the growing baby bump on the outside, taking a moment to really understand what’s happening on the inside is very insightful and awe-inspiring. There is so much happening in utero that it is hard to know where to begin!
Growing a baby inside a woman is one of science’s most amazing feats. The human body really taps into hormones and instincts that just tap into gear and know what needs to be done to make the growing baby feel at home. The body has some amazing defence and survival mechanisms when it comes to hosting a growing fetus. Even if we think we don’t know what to do, biology certainly does.
In return, the fetus does some amazing things while it is growing inside that warm and cosy womb. Starting from a cluster of cell buds and ending up with limbs and organs ready to take on the world in 9 short months, the biology of a growing fetus is truly incredible. Find out some fun biological facts about that little developing fetus and what s/he really gets up to inside the womb.
20 The Heart Starts Beating At 18 Days
It doesn’t feel like a lot happens in 18 days. That’s really just over 2 weeks, which in every day life can seem like just the standard drag at work and going through the motions. Unless it’s vacation time, 2 weeks isn’t always that significant.
Unless, of course, you’re growing a baby inside you then 18 days is remarkably amazing. Just 18 days after conception, the baby’s heart starts beating. This is pretty incredible to think that from an ova and sperm combining, a heart beat can appear in such a short amount of time. Just a few days after the heart starts beating, it also starts pumping blood. This occurs at 22 days. Often women don’t even realise they’re pregnant until two weeks after conception, and by this time the heart is already beating. This is a good reason to stay on top of things if you’re trying to conceive!
19 Fertilisation Is More Than Just An Egg
It is simple to think of fertilisation as being just an egg and a sperm colliding in the uterus. However, there is much more that happens during the fertilisation process. When fertilisation happens, the cell membrane of the sperm fuses with the cell membrane of the egg. After this, the egg undergoes a division of meiosis.
Then there are a bunch of haploids happening and diploids making chromosomes. All of this is actually happening in the fallopian tube. This is where the egg becomes fertilised and takes on the title of zygote, before it continues its journey to the uterus. Then it lodges itself to the wall of the uterus lining and this is where the fun really begins for you!
After this, the fertilisation process becomes conception. This is divided into many stages, including implantation, gastrulation, and embryogenesis in the first three weeks before moving into the fetal period.
18 Embryo To Fetal Transformation Happens At Nine Weeks
After the embryo has done its developing thing, the little cluster of cells growing inside the womb becomes a fetus. The fetal period begins at week 9 and has two main things going on. The first is rapid growth. The fetus increases 25-fold during the fetal stage in terms of cell size and number. This is most rapid at week 16. In fact, the fetus gains about 500 grams of weight in this time!
The other amazing thing that happens is the tissue and organ differentiation. This is when the cluster of cell buds start sprouting out and forming the basis of the organs they are going to become. So little lung buds start getting ready to do the breathing and little limb buds start getting ready to become arms and legs. The fetal stage really is the beginning of a mini human getting ready for life which is amazing in itself.
17 Limbs Grow From Cell Buds
The first month of conception ends with a fully formed human embryo. It doesn’t look like much, but everything at this point is ready to kick into gear and develop real baby features. This includes the arms and legs, even though they’re not visible yet.
Around days 26-28 of pregnancy, the little embryo growing inside you is about ready to transition into the fetal stage. This means that its organs and tissues are at the ready, including the little limbs that are going to make those adorably chubby arms and legs you’re going to love so much on your newborn baby.
Arms and legs form from little cell buds. Everything in the embryonic stage is a cluster of cells, but these cells are strategically placed to develop into their final feature. So arms and legs start off as tiny cell buds, and grow into themselves over the course of the 9 months.
16 The Head Is Half The Baby Early On
It is a thing that we often think of babies as having big heads. They are somewhat disproportionate during those first cuddles, but they are no where near as disproportionate as they were in the womb! Early on in fetal development, the head literally constitutes half the baby. This is because other organs and tissues haven’t developed as quickly yet, but the brain already needs space to grow.
At this point, however, the face is broad and flat and the eyes are still wide set apart. So yeah, you really have something that looks like a big-headed alien growing inside you. The good news is that the big head is going to slow so that the rest of the limbs and organs can catch up. This way when you deliver the little bundle of joy, the head is just slightly bigger than half the baby, but things are in much more humanly order.
15 The Fetus Is Ready At Six Months
So technically speaking, that little fetus is ready to become a fully fledged baby at just 6 months. Apparently the last 3 months of pregnancy are just for fun and games. Not really, they are still super important.
By 26 weeks of pregnancy, most of the vital organs are in place and bone density is getting stronger. You can feel this on the outside given how heavy the bump is getting. Babies lungs are working now so they are capable of taking in breaths of oxygen.
However, there is a good reason baby stays on longer in the womb. Not only is it warm and cosy, but it is important to reduce the risk of any serious problems. Babies born before 26 weeks are preemies (premature babies) and they are more likely to be sick. So you just stay right in that womb till you’re good and ready, little baby!
14 Babies Cry With An Accent
Apparently a baby in Spain will cry different to a baby in Thailand. This is because babies literally cry in the accent that their mom speaks with. A research team at the University of Wurzburg found that within three months of pregnancy, babies can hear and pick up the accent that their mom is talking is. They are heavily influenced by environmental language while inside the womb.
This means that the characteristics of a baby’s crying and gurgling is shaped by the accent they are exposed to while in the womb. So if you go traveling with your baby in utero (obviously before the 6 month mark), you might have a multilingual crying baby who can express their cries and gurgles in French or German. Or you can just confuse your growing baby at home by putting a different accent on everything you say. That will keep them guessing, won’t it!
13 The Fetus Arrives With 300 Bones
Babies actually have more bones than adults, in fact they have almost 50% more. When babies pop out of the womb (as if it’s that easy!) they are born with 300 bones. During development and the whole growing up process, bones fuse together. So in the transition from infancy to adulthood, the number of bones reduces to 206 because of this fusing process.
The skull is one of the main areas that experiences this fusing. At birth, there are several bones in the skull that overlap. This helps the birth of the baby so that its big head can fit through the birthing canal and squeeze out of your lady bits. On the skull, there is a really soft squishy bit called the fontanelle. After birth, the bones around this part of the skull will start fusing together and cover up the squishiness. Until then, just remember that it is normal for your baby to have a squishy head!
12 The Brain Organises Itself At Three Weeks
That’s right, it only takes 3 weeks for what is one of the most important organs to develop. From the point of conception and those little cells getting into gear, the growing fetus also starts developing a brain. As we all know, the brain is important for just about everything we do as children and adults, from cognitive process to motor reflexes as well as how we feel, see, and perceive the world around us. So it is important to get the brain right early on.
By 3 weeks, the brain starts dividing itself into the 3 fundamental sections that make it up. These include the forebrain, the midbrain, and the hindbrain. Within these 3 parts of the brain, important organs are going to develop later on during pregnancy. For instance, the cerebrum fills up most of the midbrain and takes up space in the skull. Its main function is for remembering. The cerebellum sits in the hindbrain and it is control of coordination and balance. The brain stem is found in the forebrain and it basically holds everything together in the brain.
11 The Fetus Can Feel Touch
Before the other senses of smell and taste are a thing for little growing baby inside the womb, the sense of touch is alive and well. Touch is one of the most important senses as it is a survival mechanism as well as a source of comfort and relaxation. Touch is the first sense to develop in the womb.
By 8 weeks of pregnancy, the sense of touch is beginning to register for the baby. The touch receptors in baby’s mouth and face are starting to develop as these are connected directly to the brain. By week 12, the touch receptors on the feet are in action and by week 17 the full abdomen is feeling everything. It takes 32 weeks of pregnancy for all the touch receptors to be functioning.
Therefore, the fetus can feel things, but doesn’t respond to them in the same way we do outside the womb. For instance, touch is demonstrated by the growing fetus by a change in heart rate or hormone levels. The touch messages don’t react as pain before 30 weeks.
10 Fingerprints Occur At Ten Weeks
Fingerprints are the main confirmation of identity and they are always completely unique to individuals. There is also research out there that suggests fingerprints might be a way to detect future diseases and provide information on them.
During the phases of fetal development, fingerprints begin appearing and continue transforming and developing as the baby does. They end up being a unique pattern of arches, bridges, whirls, and loops by the end of those 9 months.
During the second and third month of pregnancy, the finger pad starts developing on the fetus. This marks the threshold for fingerprint development. Interestingly enough, the overall growth rate of the finger pads on the developing fingers helps to determine where the future fingerprints and identifying skin indentations will be placed. What’s more, the exact position of the fetus in the womb will determine how the ridges of finger prints form. This is because fetuses touch the uterus lining and surrounding structures in the womb.
9 The Placenta Starts Working At Three Weeks
So during pregnancy, in addition to growing a very large belly bump, mom-to-be also grows a whole new organ. This organ is called the placenta and it grows inside the uterus. The placenta plays a crucial role during pregnancy and let’s face it, things wouldn’t get done without it.
Basically, the placenta provides oxygen and nutrients to your baby during pregnancy. It also removes any waste and nasty stuff from the baby’s bloodstream. The placenta literally attaches itself to the wall of the uterus and the umbilical cord stems from it. All of this starts happening 3 weeks into pregnancy. So yeah, just 3 weeks after conception, a bunch of cells are clustering together and growing and you’re creating a new organ. Pregnancy sure is an amazing thing! Oh, and the placenta is super cool and all, but don’t feel any pressure to eat it after giving birth. Leave that to other mammals whose instincts dominate over their ‘gross receptors’.
8 Learning Starts In The Womb
There is some evidence floating around to suggest that babies start learning in the womb. This goes back to the whole idea that listening to Mozart should start while baby is still developing on the inside. The research for this claim is most strongly supported by the fact that newborns prefer the sound of their mothers’ voice and are most comforted by this. Perhaps because they have been most closely in contact with this voice while in utero.
In some other studies, newborns were comforted by the sound of music or TV shows that their mothers listened to or watched during pregnancy. How accurate these studies are is debatable and the evidence around them isn’t well supported. Nonetheless, it is worth keeping in mind that if you’re watching trashy day time romance TV shows to appease the emotional rollercoaster, you might be giving birth to a kid predisposed to love the overdramatised acting.
7 Kneecaps Don’t Develop Until After Birth
So babies are born without kneecaps. The idea of kneecaps is there and ready, but actual things aren’t developed upon born. There is a structure of cartilage that resembles kneecaps which is going to remain just cartilage until baby is 6 months old.
It just goes to show that you think you’ve got a whole baby in your arms in those first moments after delivery, but the little munchkin is actually missing its kneecaps. Good thing they’re all wrapped up and you’re just focusing on looking at their beautiful eyes rather than inspecting the knees. All that’s there is soft and floppy cartilage.
This is pretty much the reason why newborn babies, once they get moving around, will crawl using just their arms. They literally have no kneecaps to support their little legs until they are 6 months old. So at the 6 month mark, test your babies knees and see how hard the kneecaps are feeling.
6 The Zygote Is Biologically Alive When...
When it comes to pregnancy there are so many different terms thrown around. From embryo to blastocyst, the journey from fertilization and beyond sure gets mixed up with some medical jargon. Amongst these terms is ‘zygote’. But what exactly is a zygote and when does that fertilized egg become a zygote after conception?
A zygote is essentially the beginning of conception. A zygote becomes the start of a human, meaning it is biologically alive, when the cells in the uterus are a combination of an oocyte (or an ova egg if you prefer) and that sperm who got through. When fertilization is complete and the egg and sperm have done their dance down the fallopian tube and to the uterus, this cell immediately beings producing proteins and enzymes. So basically, the zygote is alive from the moment the sperm and egg get together and a new individual life kicks into gear just like that.
5 It Takes Sixteen Weeks To Decide The Gender
Naturally, one of the most exciting things about becoming a parent is finding out the gender of the baby. This helps decide what colour scheme the nursery will be, what accessories you can deck out, and of course what name is going to be most suitable.
Realistically, the gender of the baby is decided right from the point of fertilization. However, you don’t get to find out until much later on in the process. As the fertilized egg is made up of chromosomes, it is the twenty-third chromosome which decides what the gender will be. Mom has already given an X chromosome, so it’s up to dad (or sperm donor) to give an X or Y to make a boy or girl.
Around the sixteenth or eighteenth week of pregnancy, you can find out what the gender is. This is when the sex organs are visible. This is because a small bud called a genital tuber has emerged. By the twentieth week, the sex organs will be fully formed.
4 Facial Features Are Recognisable At Four Weeks
Of course, as an expectant mom, having a guess and thinking about what the baby’s facial features are going to look like is inevitable! Will it get dad’s eyes or mom’s nose? It is a mystery of course, but the facial features actually start developing early on and are visible just four weeks after conception.
The appearance of the baby and its facial features are very much determined by your genetics and chromosomes, combined with those of the father or sperm donor. At four weeks, the ball of cells made up by these genetics is officially an embryo. Although it is just the size of a poppy seed, already the foundation of facial features is starting to emerge. By six weeks, the nose and eyes becomes more pronounced. These continue developing, along with other facial features. At about fourteen weeks, little baby can make facial expressions such as crinkling that little nose and squinting the eyes.
3 Its A Hairy Fetus Inside
Babies may come out of the womb looking all smooth and cute (after the mucus has been washed off them), but during their time in the womb they are actually quite hairy. In fact, they are hairy all over at one point. This layer of hair that babies grow in the womb is called lanugo. It is very thin and soft hair.
Lanugo is produced by fetal hair follicles which come into play during the second trimester. They are designed to keep the baby warm. This is important and all, but when you think about a hairy mini beast growing inside you, things get weird.
Even worse, babies shed their lanugo hair around 32 weeks. As it sheds, it floats back into the amniotic fluid. Remember that babies inhale and essentially eat this amniotic fluid for nutrients. So yeah, they’re eating their own hair. Well, babies are cute, but nobody ever said they were classy.
2 The Eyes Open Around Thirty Weeks
The eyes are the window to soul and a newborn baby’s eyes are something that new moms simply adore starting into. Vision is actually the last sense to develop in a baby while in the womb, so when they come out into the world everything is actually a little fuzzy (except mom’s face, of course, babies love that).
While in the womb, the baby’s eyelids remain closed. This is because little baby hasn’t actually developed retinas yet so isn’t ready to blink and open the eyes. This will change at around 28 to 30 weeks when your little baby can open their eyes and see the amniotic fluid floating around them. However, if you have twins, the two little nuggets open their eyes and can see each other, and even hold hands as their first sign of sibling affection.
Even though baby’s eyes are closed, they can still sense light. By about 18 weeks, the closed eyes can detect the small amount of light filtering through if you’re somewhere light.
1 The Baby Is Ready When It Outgrows The Womb
When baby is ready to enter the world, the whole world knows about it. The growing baby is the one who triggers labor by shifting position and essentially bouncing on some hormones to kick things into gear. Regardless of the estimated due date, only baby will know when the time is right to come out of the womb.
The reason your baby knows the time is right is because it has literally outgrown the womb. Although this place has been a nice home for the last night 9 months, there is always a time to move on. Although the uterus grows with the baby and they work as a team for most of the time together, there gets a point where the baby is simply too big and strong to keep stretching the uterus. This is why some babies are born a few weeks early and still have a healthy and normal gestational weight. Likewise, other babies need an extra two weeks growing time sometimes. So you’ve just gotta keep that womb hospitable over the 40 week mark!
Sources: Webmd.com, Todaysparent.com Momjunction.com, Biologyreference.com, Ehd.org, Whattoexpect.com, Livestrong.com, Mayoclinic.com