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Baby Development Week by Week

baby development week by week

Pregnancy is a long journey that is a different experience for every woman, and here is a quick guide to the stage of baby development week by week during pregnancy.

Stages of Baby development week by week during pregnancy

Baby Development in First Trimester

  • Week 2: You ovulate at the start of this week. If sperm enters your egg, it will be fertilized 12-24 hours later, and this simple biological event will trigger a sequence of increasingly sophisticated procedures which, if all goes well, will result in new human life. As it travels down the fallopian tube, into your uterus, and begins to burrow into the lining of the uterus over the next few days, the fertilized egg will begin to divide into many cells.
  • Week 3: A tiny ball of hundreds of rapidly proliferating cells that will grow in your baby is now nestled in the nutrient-rich lining of your uterus. The pregnancy hormone hCG, which tells your ovaries to stop releasing eggs, began to be produced by this lump, known as the blastocyst.
  • Week 4: Your block of cells has now been nicknamed an embryo. You have about four weeks after the start of your last period. It might be possible to get a positive result on a home pregnancy test around this time – when your next period is usually due. Your baby’s size is that of a poppy seed.
  • Week 5: Your child looks more like a tadpole than a human, but he is growing quickly. The circulatory system is forming, and this week the little “heart” will start to beat. Your baby’s size is that of a sesame seed.
  • Week 6: Your baby’s nose, mouth, and ears begin to form, and bowels and brain are developing. Your baby’s size is roughly the size of a lens.
  • Week 7: Your child has gained a factor of two since last week, but he still has a tail that will soon be gone. Developing arms and legs grow out small hands and feet that resemble paddles. Your baby’s size is about the size of a blueberry.
  • Week 8: Your baby has started to move, although you may not notice it. Nerve cells develop basic neural circuits as they branch out. From his throat to his developing lungs, he now has breathing tubes. Your baby’s size is about the size of a bean.
  • Week 9: Your baby’s basic physiology is in place (she even has small earlobes), but there is still a lot to come. Its embryonic tail is no longer visible. She’s only a tenth of an ounce, but she’s about to put on a lot of weight. Your baby’s size is about the size of a grape.
  • Week 10: The most crucial stage in the growth of your embryo is now complete. Her skin is still translucent, but her tiny limbs can bend and fine details such as fingernails begin to show. Your baby’s size is roughly the size of a kumquat.
  • Week 11: Your child is almost done. While you can’t feel much movement yet, she kicks, stretches, and even hiccups as her diaphragm grows. Your baby’s size is roughly the size of a fig.
  • Week 12: Your baby’s reflexes will start to kick in this week: their fingers will open and close, their toes will curl, and their mouth will make sucking motions. If you gently prick your stomach, he will feel it, although you won’t be able to feel his movements yet. Your baby is about the size of a lime.
  • Week 13: Your first trimester comes to an end this week. Fingerprints can now be seen on your baby’s little fingers, and their veins and organs can be seen through their skin. If you have a daughter, she will have over 2 million eggs in her ovaries. Your baby’s size is that of a pea pod.

Baby Development in Second Trimester

  • Weeks 14: Your baby’s brain signals have started to go off and he is using his facial muscles to communicate with you. His kidneys are also working now. You might even see him sucking his thumb if you have an ultrasound. Your baby is about the size of a lemon.
  • Week 15: Although your baby’s eyelids are sealed, they can detect light. It will move away from the beam if you shine a flashlight on your stomach. This week’s ultrasounds may reveal the gender of your baby. Your baby is about the size of an apple.
  • Week 16: Although the hair is not yet visible, the patterning on your baby’s scalp has started. Find out when you will feel your baby kick now that their legs are more developed. Its ears are close to their final position and its head is more upright. Your baby’s size is that of an avocado.
  • Week 17: Your baby’s skeleton, which was once soft cartilage, now hardens to the bone, and she can move her joints. The umbilical cord thickens and becomes stronger. Your child is about the size of a turnip.
  • Week 18: Your child is flexing his arms and legs, and you may be able to feel it. A protective shell of myelin grows around its nerves inside. Your child is about the size of a pepper.
  • Week 19: Your baby’s senses are developing, including smell, sight, touch, taste and hearing, and he may be able to hear your voice. If you feel like it, talk, sing, or read aloud to him. Your baby is as big as an heirloom tomato.
  • Week 20: Your baby can now swallow, and his digestive system is creating meconium, the sticky black gunk that he will pass into his first poo, either in his diaper or during delivery in the womb. Your baby’s size is that of a banana.
  • Week 21: Your baby’s movements have gone from beating to full kicking and banging against the walls of your uterus. As you become more familiar with its business, you may start to see trends. Your child is about the size of a carrot.
  • Week 22: Your child now looks like a newborn baby. The lips and eyebrows have become more defined, but the pigment that will colour her eyes has not yet appeared. Your baby is about the same size as spaghetti squash.
  • Week 23: Your baby’s hearing ability to detect sounds improves. She might recognize certain noises outside the womb that she now hears once she is born. Your baby is about the size of a huge mango.
  • Week 24: Your baby now has a long, lean body, but chubby times are on the way. Her skin is still thin and translucent, but that will change shortly. Your baby is the size of an ear of corn.
  • Week 25: Your baby’s wrinkled skin fills with baby fat, making it look like a newborn baby. Her hair is starting to grow, and it’s already coloured and textured. Your baby has reached the weight of a typical swede.
  • Week 26: Amniotic fluid is now inhaled and exhaled by your child, making it easier for their lungs to develop. These breathing exercises can help you prepare for your baby’s first breath. Your baby’s size is that of a bunch of green onions.
  • Week 27: Your second trimester ends this week. Your baby’s brain is incredibly active, and she sleeps and wakes up on a regular schedule. His lungs are not fully developed, but with medical assistance, they can function outside the womb. Your baby is the size of a cauliflower head.

Baby Development in Third Trimester

  • Week 28: Your baby’s eyesight is improving and he will soon be able to detect the light coming from outside. His eyelashes have grown and he can blink. Your child is about the size of an eggplant.
  • Week 29: Your baby’s muscles and lungs are working hard to prepare him for life outside the womb, and his skull is enlarging to accommodate his growing brain. Your baby’s size is that of butternut squash.
  • Week 30: A pint and a half of amniotic fluid surrounding your baby, however, this will decrease as he grows and takes up more space in your uterus. Your child is as big as a giant cabbage.
  • Week 31: Your baby’s head can now turn side to side. Under her epidermis, a protective layer of fat forms, swelling her arms and legs. Your baby’s size is that of a coconut.
  • Week 32: You are probably gaining a pound a week. Half of that goes to your baby, who will grow one-third to one-half of her birth weight over the next seven weeks as she prepares to leave the womb. Your baby is about the size of a jicama.
  • Week 33: Your baby’s skull bones have not yet bonded. As his head squeezes into the birth canal, it allows them to adjust. They will not merge until they are adults. Your child’s height is as big as a pineapple.
  • Week 34: Your baby’s central nervous system and lungs are maturing. In the long term, babies born between 34 and 37 weeks who do not have significant health problems do well. Your baby is as big as a melon.
  • Week 35: It’s starting to get cramped in your stomach! Your baby’s kidneys and liver are fully mature and she can process some waste products. Your baby’s size is that of a honeydew melon.
  • Week 36: Your baby is growing at a rate of about one ounce per day. She is also losing most of her fine down, as well as the vernix cases, a waxy substance that has covered her skin until now. Your baby is the size of a head of romaine lettuce.
  • Week 37: Your due date is approaching, but despite the fact that your child appears to be a newborn, he is not yet ready for the outside world. His lungs and brain will mature over the next two weeks. Your child is as big as a bunch of Swiss chard.
  • Week 38: Want to know what colour your baby’s eyes are? Because her irises are not fully pigmented, if she was born with blue eyes, they may darken until she is about a year old. Your baby is as big as a leek.

End an entire term

  • Week 39: Your baby’s physical development is complete, but he is still accumulating fat which will help him control his body temperature in the outside world. Your baby’s size is that of a watermelon.
  • Week 40: You might not be as late as you think if you’re past your due date, especially if you calculated it only on the day of your last period. Women ovulate later than expected on occasion. If you don’t get to work on your due date yourself, your doctor will likely perform tests (such as an ultrasound and a non-stress test) to make sure it is safe for you to continue your pregnancy. Your baby’s size is that of a small pumpkin.
  • Week 41: Your child is now classified late for the quarter. Since going more than two weeks past your due date can put you and your baby at risk, your doctor will most likely discuss the induction of labour with you.

Labour and delivery

It’s amazing to meet your baby for the first time, but the events leading up to this stage are unpredictable, so it’s reasonable to be afraid.

Here are some tips to help you get ready for the big day.

Read more: Different stages of pregnancy

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