Week 1 During the first week, women are still going through their last menstrual cycle before pregnancy. The uterus is shedding its lining, and the last month’s unfertilized is being shed through the period. As the period ends, more eggs are maturing in the ovaries for the next cycle. The pregnancy's first-week symptoms are the same as the menstrual cycle symptoms and involve uterine cramps, breast tenderness, headaches, mood changes, back pain, fatigue, and acne.
Week 2 The second week of pregnancy is when the body starts preparing for ovulation which can occur between 13 to 20 days after the first day of the last menstrual period. During week 2, several follicles in the ovaries are maturing to release one egg during ovulation. One of these eggs would have become dominant and triggers the release of estrogen that prompts the uterus to thicken the lining with blood in preparation for the fertilized egg. Just before the ovulation occurs, there is a spike in the luteinizing hormone (LH), which ovulation kits can detect. The luteinizing hormone prompts the mature egg to burst from its follicle. The egg is alive for about 12 to 24 hours, before which it has to be fertilized by the waiting sperm. Read More
Week 3 If the ovulation and fertilization occurred on week 3, then it can be said that conception has occurred. About 30 hours after the egg is fertilized, it divides into two cells, at which point it is called a zygote. The cells of the zygote continue to divide as it moves down the fallopian tube towards the uterus. It takes about 3-4 days for the zygote to reach the uterus after fertilization. It continues to stay as a dividing mass of cells that floats around the uterus for 2-3 days.
Week 4 By the end of the 4th week, the floating mass of dividing cells attaches itself to the uterine wall in a process termed implantation. At this stage, it is called a blastocyst. It is a lump of about 200 cells that is 0.2mm wide and made up of multiple layers of cells. The outermost, later called ectoderm, would eventually develop into the brain and nervous system. The middle layer, which is called the mesoderm, will develop into the heart, blood vessels, bones, and muscles. The innermost layer called the endoderm will develop into the digestive and respiratory systems. The blastocyst also has an outer layer called chorionic villi, which are tentacles like appendages that will develop into the placenta. Read More
Week 5 The embryo has burrowed deep into the uterine wall by this time, and women might experience week 5 pregnancy cramps. The embryo that is about 2mm in size now has cells that will form into all the major organs, and it is within the amniotic sac- a bag of fluid that will protect the fetus. Some of the earliest systems to develop are the brain, spinal cord, and face. The spinal cord, which looks like an open groove at this point, is called the neural tube. The head is noticeable on one end of the embryo, being larger than the rest of the body. The baby’s heart will also start beating this week, and a thin string-like blood vessel that connects the embryo to the uterus will eventually become the umbilical cord.
Week 6 Throughout week 6, the embryo develops rapidly and grows to about 4mm in size by the end of the week. By this time, it resembles a curved tadpole with a head and a tail. The organs inside are developing, and a week 6 pregnancy ultrasound scan at the clinic can even show the beating heart. The different layers of cells at this stage have different functions and develop into various organs. The eyes and the jaws are starting to form, and tiny buds that will become the limbs also start to appear. Read More
Week 7 By pregnancy 7th week, the embryo would have grown to a size of about 10mm. The brain continues to develop rapidly, and the head is noticeable as it is much bigger than the body. The eyes would start forming in the face along with tiny buds, which will eventually become the ears. The spinal cord and internal organs also start developing. The embryo is now inside the amniotic sac- a bag-like membrane that envelops the embryo. The placenta is developing and starting to attach to the uterus to derive oxygen and nutrients from the blood. The heart is also developing and beating at a rate of 150-180 beats per minute.
Week 8 As women move to the eight-week pregnancy, the embryo gas grows bigger to about 13mm, however, it still looks like a tadpole, and the tail will gradually disappear. The head is developing more distinct features such as the eyes and nose, and ears. Inside the head, the tongue, jaw, and the roof of the mouth are all coming together. The buds that will eventually become arms have hands growing out with webbed fingers. Read More
Week 9 The fetus continues to grow quickly, and the week 9 pregnant baby size is about 2 cm long. By now, they can also move by tossing as turning as their tiny muscles have developed enough to function. However, they spend most of their time in a curled up fetal position that looks like they are hugging themselves. Although their skin is still transparent, the shape is more recognizable as their large heads have a distinctive face forming. Their liver is making blood cells, and blood vessels can be seen underneath the skin.
Week 10 The fetus by 10 weeks is about 3.5 cm long and weighs about 8g. The tail and their tadpole-like appearance have disappeared, and they are starting to look more human. Although the internal organs have developed, they are not functional yet. Their face has developed lips, nostrils, and ears, while on the inside, the jaw bone is starting to develop teeth. The fetus also has internal sex organs at this point, but it is not visible enough to be seen on the outside. The brain is also developing fast and has enough activity to be picked up in the form of brain waves. The heart now has 4 chambers and beats rapidly, close to 180 beats per second. The fetus’s limbs have also formed with tiny toes and fingers along with the joints. Read More
Week 11 As the pregnancy progresses to the 11th week, the fetus is about 4.5 cm long and weighs about 10g. The nervous system and the brain have almost developed, and the muscles are being controlled by the nerves, which allow the fetus to make small movements in the uterus. The body of the fetus and head are almost of the same length, and the arms and legs are tucked in the front. The fingers and toes have nails, while the gums in the jaw have tiny teeth. The nasal passages are open, and the tongue has formed.
Week 12 By 12 weeks of pregnancy, the fetus has grown to 6 cm long and weighs around 18g. It is not fully formed, and the size has doubled since last month. As all the organs and the limbs have fully developed, the fetus fills up the volume of the uterus. The body is now bigger, and the head is only about half the size of the body. While the arms look proportionate to the size of the body, the legs are still short. At this point, the kidneys of the fetus are functioning and passing urine. The fetus also swallows the amniotic fluid and practices breathing movements. The digestive system is also starting to function to practice for birth. The heartbeat of the fetus is also strong and can be heard with a heart monitor. Read More
Week 13 By the 13th week, women enter the second trimester of pregnancy, and the fetus is about 7.5 cm long and weighs close to 30g. They also move inside the uterus extending the arms and legs, and also suck the thumb while making a fist. Several of the major organs are also functions, such as the liver and pancreas. The kidneys function to produce urine that gets mixed with the amniotic fluid. The fetus also practices swallowing and breathing. In the face, soft hair is beginning to grow to form the eyebrows. The genitalia of the fetus also start developing at this point but is too small to be detected in a pregnancy ultrasound scan. Read More
Week 14 The pregnancy 14 weeks baby size is about 11cm long and weighs close to 45g. The organs have formed in the body, and some have started functioning. The fetus’s face is starting to become more recognizable with the eyes fully developed and protected by eyelids that are still fused. The fingers and toes have formed with growing nails. The fetus’s reflexes have also started functioning and are responsive to movements though women would rarely be able to sense it. Read More
Week 15 The pregnancy second-trimester baby development begins to progress much quicker now as the body gains more than the head and grows faster. By the end of the 15th week of pregnancy, the fetus would measure about 12cm long and weigh close to 80g. As the bones in the ears begin to develop, they will be able to hear sounds for the first time. The fetus would hear the sounds of the heartbeat, the flow of blood throughout the body, the sounds of the digestive system, and voice. While the eyelids are still fused shut, the eyes can still respond to light. The fetus is covered in fine hair called lanugo all over the body, which eventually falls away before birth. It is also making movements and can grip with the fingers and suck the thumb.
Week 16 The pregnancy 16 weeks size of the fetus is about 12.5cm long and weighs close to 110g. The fetus will now enter a growth spurt which will lead them to nearly double their size over the following weeks. Facial features are more distinct as the eyes move closer in the face and the ears are at the side of the head, giving the fetus a more human-like appearance. The skeletal joints are functional, and the fetus can wriggle and turn inside the uterus while flexing the muscles of the limbs. They can also twitch their facial muscles but cannot control them completely. The umbilical cord formation is complete by this time, along with 2 arteries and 1 vein to transport blood and nutrients. Read More
Week 17 The fetus continues to grow rapidly during week 17, adding more weight much faster than it did before. By the end of the 17th week, they would be about 13 cm long and weigh close to 150g. During this stage, the fetus begins to accumulate a layer of fat called adipose tissue that has a range of functions, from keeping them warm to help them gain weight and defining their bodily features. The genitals are fully formed and can be seen in a subsequent pregnancy ultrasound scan. The fetus also begins to swallow the amniotic fluid that helps the kidneys function to produce and pass using once about every hour. The umbilical cord is also becoming thick and strong.
Week 18 The fetus continues to gain weight by the 18th week and is about 200g by the end of the week. They are about 14cm long and move in the uterus. The body has developed enough for the fetus to have hair, eyebrows, and fingernails. They can also have hiccups or yawns at this point. Since they begin to move and turn, many women begin to feel the flutters and bubbles in their abdomen while resting. This is because the activity of the fetus is more likely to be felt when women are resting than when they are active. Read More
Week 19 During week 19, the fetus is about 15cm long and weighs close to 260g. They have regular sleeping and waking cycles and might sleep up to 18 hours a day and stay awake for about 6 hours when most women experience their pregnancy baby movement feeling. They can also respond to sounds from outside, and this is a good time to play music which they may be able to recognize once they are born.
Week 20 As the pregnancy progresses to the fifth month, the fetus is close to 16cm long and weighs around 320g. They are quite active by now, and most women begin to feel their pregnancy 20 weeks baby movement frequently. They are able to hear sounds from within the body and outside the womb, although their ears still haven’t developed completely. The fingers now have fingerprints, and the skin is covered with a vernix-a white substance that acts as a barrier from the amniotic fluid. Cartilage in the body of the fetus will now start to turn into bone. The jaws continue to develop, and permanent teeth begin to develop inside the gums. Female fetuses will also have eggs in their ovaries by this time. Read More
Week 21 The fetal growth spurt has slowed down, and it weighs about 390g by the 21st week of pregnancy and is close to 18cm long. The expanding uterus filled with amniotic fluid gives the fetus more space to move about, and this is the first time that others can feel the pregnant baby kick by placing their hand on the belly. The brain has entered a phase of rapid development by the 21st week, and there is soft hair covering the head. Development of the uterus can be seen in female fetuses while males develop testicles.
Week 22 The pregnancy week 22 size of the fetus is about 19cm long and weighs close to 460g. Some of their organs, such as the eyes and ears,s have now fully formed, and they can hear sounds from outside the womb. They become increasingly active as the weeks pass and often turn around in the uterus, changing positions throughout the day. The kicks and the movements are also stronger as their muscles grow strong and they gain more control over their limbs. Read More
Week 23 By the 23rd week of pregnancy, the fetus continues to develop and is about 20cm long, and weighs close to 540g. Along with the hair on the head, the whole body is covered with lanugo which can be seen in an ultrasound scan. The fetus practices breathing in the uterus, although its oxygen supply comes from the placenta. The lungs are filled with a surfactant that will become helpful to keep them inflated after birth. The brain and nervous system continue to develop rapidly, along with an improvement in vision and hearing.
Week 24 The pregnancy week 24 baby size is about 25cm long and weighs a little over 600g. The brain continues to develop rapidly, and the senses such as eyesight, hearing, and even taste develop further. The fetus can hear sounds from outside and even respond to light. The lungs are in a steady growth phase, getting filled with a surfactant that helps keep them inflated after birth. All the organs and systems in the body have developed enough to allow a premature baby at 24 weeks to survive. However, they need to be delivered at a hospital and placed inside a neonatal unit under expert care. The downside to premature babies born at this point is that they have a high chance of developing a disability such as blindness or cerebral palsy. Read More
Week 25 By week 25, the fetus would have gained more weight and reached about 700g. They would also be close to 30cm long and take up most of the space in the uterus. They will open their eyes for the first time around this week as the brain begins to regulate the movements of the eyeballs and eyelids. The rest of the senses have also developed well while the digestive, respiratory and nervous systems are still catching up. Premature babies born around this time still have about an 80% survival rate when kept in a neonatal unit.
Week 26 During the seventh month of pregnancy, by week 26, the fetus measures more than 33cm long and weighs close to 900g. They are fast depositing a layer of fat under the skin and growing newer muscle tissue which makes them look more human as the weeks pass. The third-trimester baby movement is also more prominently felt by women as the fetus begins to respond to the sounds and light from outside the womb. They will also respond if the belly is touched or the hand is rubbed firmly over the tummy. Read More
Week 27 By week 27, the fetus weighs more than 900g and will be about 36cm long. Their muscles continue to develop, and the body looks proportionate for the first time. They will continue to put on more weight in the upcoming weeks. The skin also goes from being transparent to red and wrinkly while being covered with a waxy coating called vernix for protection. They respond well to sounds and touch and kick whenever someone tries to interact.
Week 28 By week 28 of pregnancy, the fetus is about 37cm long and weighs a little over 1kg. As the body develops rapidly, it looks more in proportionate to the head, and the fetus looks like a normal human baby. Since they are gaining weight quickly, they have lesser space inside the uterus to move around, and the pregnancy 28 weeks baby position can be expected to be in what is called the breech position- the head is up and the bottom facing downwards. Weeks before delivery, the fetus naturally turns around to get into a head-down position. Read More
Week 29 The fetus continues to gain weight into week 29 and will be close to 1.15kg. At this stage, they are about a third of the size they will be at full term, which is 37 weeks. Their lungs are developed and have started breathing more rhythmically, and their heartbeat can be heard using a stethoscope or by placing the ears on the belly. They have opened their eyes and can focus and look around.
Week 30 During week 30 of pregnancy, the fetus is developing a layer of fat under the skin, which makes them look chubbier and less skinny. The wrinkles on their skin also smoothen out, and they start taking on the more familiar appearance of a human baby. They will be about 38cm long and weigh close to 1.3 kg. The lanugo which covered their body throughout the weeks is starting to disappear, and more hair begins to appear over the head. The fetus also develops some basic reflexes such as sucking the thumb and is able to sense the false labor contractions. Read More
Week 31 By week 31, the fetus is 41cm long and weighs close to 1.5 kg. It has gained lots of muscle mass and fat deposition, making it look slightly plump. The brain continues to develop rapidly and is now controlling most of the body. They can open their eyes and focus and even respond to startling noises or intense light.
Week 32 The fetus during week 32 of the third trimester of pregnancy would be about 40cm long and weighs close to 1.8 kg. They have been gaining weight rapidly and nearly doubled since the last month. They will continue to grow faster, occupying most of the space inside the uterus. Although it is crowded inside, the fetus will manage to turn around and go into a head-down position from a breech position around this time. Some will continue to stay in the breech position until the last month. They will also show lesser activity as they are asleep most of the time. However, one of the third-trimester symptoms not to ignore is the complete cessation of fetal movement. In such a case, the doctor needs to be contacted immediately. Read More
Week 33 By week 33 of pregnancy, the fetus gains weight and reaches a little over 1.9 kg. Their growth in terms of length slows down, and they begin to put on more weight. The lungs now are mature enough to breathe outside the uterus and are getting filled with a surfactant which enables it to inflate easily. The brain and the nervous systems are close to being fully developed, and their reflexes are beginning to become more coordinated. The fetus also continues to store iron reserves in the liver, which will be necessary for the first 6 months of their life.
Week 34 The fetus by week 34 of pregnancy weighs close to 2kg and measures around 45cm long. They are too big at this point to move around freely; however, mothers will continue to feel their kicks and might even experience slight discomfort when they roll over. Their immune system is developing fast to prepare for birth as they will be exposed to different pathogens once outside the uterus. The bones of the fetus continue to build up calcium and become harder; however, the bones are still soft and flexible until birth. The soft bones aid in the birthing process as they relieve pressure by being flexible. The same applies to the skull of the fetus, which is made out of 6 separate bones that remain un-fused to allow the head to deform as they pass through the birth canal slightly. The fontanelle fetal skull (soft spot) of the skill can be felt after birth and until 18 months as the brain continues to develop. Read More
Week 35 The fetus is a little over 45cm long and weighs close to 2.3kg by this time. Since they have put on more weight, they will spend most of their time in the typical fetal position of having their knees bent up to their chest. If the pregnancy week 35 baby position is still in breach- with the head up and the bottom down, it is not a cause for concern as most fetuses flip around as the due date approaches. If they still continue to stay in the breech position for a few more weeks, the doctor will try to turn them around using a procedure known as External Cephalic Version (ECV).
Week 36 By this time, the fetus is curled up in the uterus as there is little room left to move about freely. The pregnancy week 36 baby weight is close to 2.5kg, and they measure over 45cm. Their lungs and digestive system have developed fully at this stage to enable them to survive being born prematurely. They can breathe and digest milk even if they are born at this point, and they will be considered full-term in 2 weeks. Most fetuses move from their breach position to ‘engage’ during these weeks. The pregnancy 9th-month baby position is generally inverted with the head pointing down and the bottom pointing up. However, some babies engage just before labor starts. Read More
Week 37 As the fetus approaches week 37, it is close to being full term and will have all the features and appearance of a newborn baby. They would have gained more weight to reach 3.0kg and measure close to 48cm from head to toes. Their reflexes have also developed, and they can grip objects firmly with their hands. The intestines of the fetus contain meconium, a sticky green substance that will become their first excrement soon after they are born.
Week 38 By this week, the fetus is about 3.2kg in weight and measures close to 48cm in length. They could still have some of the fine body hair- lanugo that they had throughout the gestational period. The hair usually disappears completely by the time they are born. The body would be covered with the protective vernix that shields the skin from the amniotic fluid. The fetus, at this point, is fully developed and can survive being born. In some instances, the meconium, which forms the first excrement of the fetus, can be released early, causing the amniotic fluid to turn green. Since it is a sign of distress, the baby will be monitored soon after birth in such an event. The pregnancy 38-week baby movement is sporadic as there is almost no room for them to move around. Read More
Week 39 As pregnancy progresses to week 39, the fetus slows down the weight gain. They would be about 3.3kg and measure a little over 48cm in length. Males will have fully descended testicles, and all fetuses will have a reserve of fat under the skin.
As the due date comes very close, most women don’t need any more pregnancy scans. However, those who have had complications during pregnancy such as preeclampsia or gestational diabetes, or multiple babies need a final check by the doctor to ensure everything is good for the delivery. The week 39 position of the baby will be checked to see if they are still in the breech position.
Week 40 By week 40 of pregnancy, the fetus is fully developed and weighs a little over 3.5kg, and measures about 50cm; however, healthy full-term babies can vary in weight from 2.9kg to 4.2kg. Their movements just before the approaching days of labor can slow down because of the limited space in the uterus. But if women find that the baby has completely stopped moving, it is important to contact the doctor about it. Read More