You ought to track your fetal development week by week. The baby is always growing and developing from conception to labor. Your unborn child goes through several developmental stages as it develops from a blastocyst to an embryo to a fetus. Your baby’s heart will start to beat around week 5, they’ll have regular sleep and wake cycles by week 27, and they’ll be physically mature by week 39. Use this timeline to see your baby’s size and development during the course of the pregnancy.
From conception to labor, these incredibly detailed, medically reviewed photos allow you to follow your baby’s development week by week.
2 weeks: Fertilization
You ovulate at the start of this week. If sperm enters your egg, it will fertilize 12 to 24 hours later. The fertilized egg will begin to divide into several cells during the following few days as it passes down the fallopian tube, enters your uterus, and begins to penetrate the uterine lining.
Three weeks: Implanting
Currently, a minuscule ball of hundreds of rapidly replicating cells that will become your baby is snuggled in the nutrient-rich lining of your uterus. A blastocyst is a ball of cells that has started to release the pregnancy hormone hCG, which instructs your ovaries to cease producing eggs.
4 weeks Fetal Development Week by Week
Your cell mass is now recognized as an embryo. About 4 weeks have passed since the start of your last menstruation. You might be able to get a positive response on a home pregnancy test at this time when your next period would typically be due.
Your infant is about as big as a poppy seed.
Although it looks more like a tadpole than a human, your baby is developing quickly. This week, the small “heart” will start to beat as the circulatory system starts to take shape.
Your infant is about as big as a sesame seed.
Related post: Infant Growth Chart
Your baby’s intestines and brain are beginning to form, and its nose, mouth, and ears are beginning to take shape.
Your infant is about as big as a lentil.
7 weeks Fetal Development Week by Week
Since last week, your kid has grown in size by a factor of two, yet it still has a tail that will soon go. The developing arms and legs are sprouting little hands and feet that resemble paddles more than anything else.
Your infant is about as big as a blueberry.
Although you won’t feel any movement just yet, your baby has begun to move. Primitive brain pathways are being formed by the branching out of nerve cells. Their developing lungs are now connected to their throat by breathing tubes.
The size of your infant resembles a kidney bean.
9 weeks Fetal Development Week by Week
Even if your baby already has little earlobes, there is still more development to be done in terms of basic anatomy. They are only a fraction of an ounce in weight and have lost their embryonic tail, but they are going to start growing weight quickly.
The most important stage of your embryo’s growth is over. They still have translucent skin, but their tiny limbs can bend and even the smallest of characteristics, like nails, are beginning to take shape.
A kumquat would be the size of your baby.
11 weeks Fetal Development Week by Week
Your child is almost finished developing. You can’t feel any movement yet, but they are kicking, stretching, and even hiccupping as their diaphragm grows.
Your infant is about as big as a fig.
Your baby’s reflexes begin to develop this week: Although you won’t yet feel their movements, their fingers will soon start to open and close, their toes will curl, and their lips will make sucking motions.
The size of your infant is that of a lime.
Your first trimester is coming to an end this week. Your newborn’s tiny fingers now bear fingerprints, and their skin is transparent enough to reveal their veins and internal organs. She has more than 2 million eggs in her ovaries if you’re having a girl.
Your infant is about the size of a pea.
You can see in this graphic how big your baby is at the start of your second trimester, but also how little they are.
An early miscarriage is substantially less likely after the first trimester. Additionally, many expectant mothers no longer experience early pregnancy symptoms like morning sickness and exhaustion. Start a regular pregnancy exercise routine now if you haven’t been working out but are feeling more energized.
Brain impulses in your infant have started to fire, and they are exercising their facial muscles. Their kidneys are now functioning as well. The sucking of their thumb may even be visible on an ultrasound.
Your infant is about as big as a lemon.
Even though their eyelids are still fused shut, your baby can perceive light. They will flee the light if you shine a flashlight on your stomach. This week’s ultrasounds may reveal the gender of your unborn child.
The size of your infant is an apple.
16 weeks Fetal Development Week by Week
Although their hair isn’t yet visible, your baby’s scalp has started to take on a pattern. Their ears are getting close to their final position, their head is more upright, and their legs are more developed.
Your infant is about as big as an avocado.
Your baby’s joints can move, and their once-soft cartilage skeleton is now transforming into bone. The umbilical cord is getting thicker and more robust.
Your infant is about as big as a turnip.
18 weeks Fetal Development Week by Week
You might feel the motions of your baby’s arms and legs as they flex. Around their nerves inside, a layer of myelin is developing as protection.
The size of your infant resembles a bell pepper.
Your kid may be able to hear your voice as their senses, including smell, vision, touch, taste, and hearing, are still developing. If you feel like it, you could sing, talk, or read aloud to them.
Your infant resembles an heirloom tomato in size.
Your kid can swallow now, and their digestive system is creating meconium, which they’ll pass in their first poop, either in their diaper or in the womb before birth. Meconium is a dark, sticky substance.
Your infant is about as big as a banana.
Your baby is now kicking and jabbing against the walls of your womb in addition to its previous fluttering movements. As you get used to their behavior, you could begin to see patterns.
Your infant is about as big as a carrot.
Your infant now resembles a little newborn. Lips and brows are more pronounced, but the pigment that will give their eyes their color is still missing.
The size of your infant resembles a spaghetti squash.
23 weeks Fetus Development Weekly
The ability of your baby’s hearing to detect sounds is improving. After birth, infants might recognize some of the sounds they hear inside the womb now.
Your infant resembles a huge mango in size.
24 weeks Fetus Development Weekly
Although your baby is still very tall and slim, times are about to get fatter. Even while their skin is still thin and translucent, it will soon start to alter.
Your infant is about the size of a corn ear.
25 weeks Fetal Development Week by Week
Baby fat is beginning to fill out your baby’s wrinkly skin, giving them a newborn appearance. Their hair has color and texture and is just starting to grow.
Your infant now weighs about the same as a typical rutabaga.
Amniotic fluid, which aids in the development of your baby’s lungs, is now being inhaled and exhaled by them. These breathing exercises are helpful in preparation for the newborn’s initial breath of air.
Your infant is about the size of many onions.
27 weeks Fetal Development Week by Week
Your second trimester is coming to an end this week. Your baby’s sleep and wake cycles are now regular, and their brain activity is high. Even though their lungs aren’t fully developed, with the right medical care, they may function outside the womb.
Your infant is the size of a cauliflower head.
28 weeks Fetal Development Week by Week
Your baby may be able to detect light leaking in from the outside as their eyesight matures. They have developed eyelashes and can blink.
Your infant is about as big as an eggplant.
29 weeks Fetal Development Week by Week
Your baby’s head is expanding to make room for its growing brain, and its muscles and lungs are hard at work getting ready to operate in the outside world.
The size of your infant resembles a butternut squash.
A pint and a half of amniotic fluid surround your baby, though this amount will decrease as they grow and take up more room within your uterus.
Your infant resembles a huge cabbage in size.
31 weeks Fetal Development Week by Week
Your infant’s head may now turn from side to side. Under their epidermis, a layer of protective fat is building up, elongating their arms and legs.
Your infant is about as big as a coconut.
Currently, you’re probably gaining a pound per week. Half of that goes directly to your unborn child, who in the following seven weeks will gain between one-third and half of their birth weight in preparation for life outside the womb.
Your infant is about as big as jicama.
33 weeks Fetal Development Week by Week
Your baby’s skull’s bones have not yet melded together. Consequently, they can move around when their head passes through the birth canal. They will not totally merge until they are adults.
The size of your infant resembles a pineapple.
34 weeks Fetus Development Weekly
Both your baby’s lungs and central nervous system are developing. Long-term outcomes are often favorable for infants who are born between 34 and 37 weeks and who are healthy otherwise.
The size of your infant resembles a melon.
It’s becoming constrictive inside your womb! Your baby’s liver can process certain waste materials, and its kidneys are fully grown.
Your infant is about as big as a watermelon melon.
36 weeks Fetus Development Weekly
An ounce or so is added to your infant every day. Together with the vernix caseosa, a waxy substance that had been defending their skin up until now, they are also losing the majority of the lanugo hair that covered their bodies.
The size of your infant resembles a head of romaine lettuce.
Although your baby appears to be a newborn, your due date is rapidly approaching, and your baby is now regarded as being at term. Their lungs and brain will continue to develop over the ensuing two weeks. You could give birth at any moment.
Your infant is about the size of some Swiss chard.
Are you interested in your child’s eye color? If they are born with blue eyes, they may change to a darker color up until they are about a year old since their irises are not fully pigmented.
Your infant is about as big as a leek.
Your baby’s physical growth is complete, but they are still actively gaining weight and expanding in size.
Your infant resembles a small watermelon in size.
If you’re past your due date, you might not be as late as you believe, particularly if you only used the day of your most recent period to determine it. Women occasionally ovulate later than anticipated.
To ensure that you can safely continue your pregnancy, your doctor will monitor you constantly.
The size of your infant resembles a little pumpkin.
Your child is now regarded as being late-term. Your healthcare practitioner will likely discuss inducing labor with you if you are more than two weeks past your due date because doing so can put you and your unborn child at risk for issues. To make sure your baby isn’t in any fetal distress, they may perform a fetal non-stress test while they watch your contractions and fetal heart rate.