Pregnancy Week by Week, a Detailed Overview

Pregnancy | | Nicole Lane
25 min read

Meeting your little one will be here — between the nausea, swollen feet, and bodily changes — before you know it. Every week on the pregnancy journey is different, and we’ve broken down the stages of pregnancy and what you can expect. 

Week 1-2

From the very first day of your last period, the pregnancy countdown begins; however, the first two weeks are when your body gets ready for ovulation, which means an egg is released from one of the ovaries. So, you’re technically not pregnant yet in week one, but by week two, if you decide to conceive in week one, you’ll be two weeks pregnant. 

Week one is the best time to conceive, as you’re most fertile in the days leading up to ovulation. Within 24 hours of ovulation, the egg is fertilized by sperm. After five or six days, the egg implants into the womb. Some women claim they can feel this process — but not everyone can. 

Congrats! Implantation means you’re pregnant. Approximately 15 to 25 percent of women bleed lightly during implantation. The majority of women will feel cramping. 

Week 3

Of course, not everyone knows they are pregnant, and a test is required to ensure that the pregnancy glow is real. These tests, either bought at home or taken at a doctor’s office, detect the presence of human chorionic gonadotropin (hCG), a hormone found during a urine test. By the end of week three, people typically get a positive pregnancy test. While some tests can detect pregnancy after five days of a missed period, waiting until your third week can ensure accurate results. 

Pregnancy symptoms usually don’t rear their head during week three. The best is yet to come. What most women feel during this time is cramping, spotting, bloating, or breast tenderness. Hormones are also beginning to go haywire during this time, so your sense of smell could be altered. 

As for your baby, there are several hundred cells that are rapidly multiplying in your uterus. The cells that multiply in the middle will become the embryo, and the cells on the outside become the placenta. 

Week 4

Buckle up, this is when the embryo begins to grow within the lining of the womb. Those cells that were multiplying in week three, now they are forming into several layers that grow into different parts of your baby’s body. 

  • The inner layer becomes the breathing and digestive system. Examples: lungs, gut, and bladder. 
  • The middle layer makes up the heart, blood vessels, muscles, and bones. 
  • The outer layer is the brain and nervous system. Examples: tooth enamel, skin, and nails. 

During this time is when your baby is the most vulnerable to development. That’s why it’s crucial you stay away from alcohol, smoking, and drugs. 

In week four, this is also when an amniotic sac surrounds the poppy-seed-sized embryo, which will protect and cushion the baby. The embryo also has a yolk sac, which provides nourishment before the placenta is fully formed. 

Expect breast tenderness, darkening nipples, exhaustion, possible morning sickness, gas, bloating, mood swings, and cramping. 

Week 5

Your embryo is now the size of a sesame seed. Not much bigger than last week, but developing rapidly. The heart is forming, and blood vessels are beginning to circulate blood. The formation of the blood vessels makes up the umbilical, which will connect you to your baby. 

On the outer layer of cells of the embryo, a hollow tube called the neural tube will form. This is the baby’s brain and spinal cord. In order to prevent any issues with the neural tube, like spina bifida, your doctor will recommend taking folic acid. It’s often suggested to take folic acid even before you get pregnant if you’re planning ahead. The Centers for Disease Control and Prevention say that women should take 400mg a day even if they aren’t pregnant. 

This is around the time many women realize they are pregnant if they didn’t know beforehand. It’s usually a good idea to create a maternity plan around this time and begin working with a midwife, doula, and doctor. 

Week 6

This is the exciting time when you can hear your baby’s heartbeat, although it isn’t fully developed yet. It usually beats around 160 beats per minute. 

The embryo is shaped like a tadpole at this point in the pregnancy, with arms and legs becoming slightly visible as little nubs. This is also when the skin begins to grow, slightly covering the embryo in a see-through layer. 

Week 7

The embryo is the size of a blueberry now and is 10mm long. During this time, the brain is developing quickly and is larger than the rest of the body. Inner ears begin to develop but the outer ears have still yet to appear. Eyes, nose, and mouth are slowly becoming more apparent. Your little seed is taking on a human form, finally. 

In terms of your body, the womb is the size of a lemon. Breasts are enlarged, sore, and many women begin to pee more often. Many women become nauseated when being exposed to certain smells. This is because estrogen levels are increasing in your body. Suddenly, your pet stinks. And so does your partner. Don’t worry, this heightened nausea is temporary and will go away later on in your pregnancy. 

During this time, some women report gum or tooth issues. The good news is that in the United States, dental care is free during pregnancy due to the importance of mouth hygiene. 

Speaking of mouth health, you may experience excessive salvia during this time, too. This is due to hormonal changes, nausea, and heartburn. Make sure to eat a balanced diet to avoid heartburn, brush your teeth more often, and stay hydrated. 

Of course, not all women experience these types of symptoms. Some don’t experience any at all, although 90 percent of women have at least one new side effect. 

Week 8 

Guess what, you’re two months pregnant. Time flies and there are only seven more months to go. 

At this time, your baby is raspberry-sized, although this does differ for every pregnancy. Your embryo now has lips, a full nose, and eyelids. The baby’s hands and feet are webbed, but you can definitely begin to feel them moving. This is usually when the baby’s limb nubs begin to twitch. The amniotic fluid is increasing, which means the womb is also growing in size to prepare for a much bigger baby in the coming weeks. 

During this time, you may begin experiencing a white discharge due to more estrogen. Fear not, this is a totally normal discharge, called leucorrhea. If your discharge is green, has a strong unpleasant smell, or causes itching, visit your doctor right away as you may have an infection. 

Along with the symptoms we’ve mentioned before — heightened smell, nausea, gorged breasts, — a new symptom is pregnancy dreams. These dreams are often described as bizarre and realistic. 

Due to increased blood flow, headaches become much more common for pregnant women. Moreover, many women cut out caffeine which could lead to headaches. Ask your doctor before taking over-the-counter pain medication, however acetaminophen is typically safe to use. However, aspirin, ibuprofen, and migraine drugs are not safe. 

During this time, 3 percent of women have hyperemesis gravidarum, which is extreme morning sickness

Week 9

Your embryo is beginning to have a face, a tongue, ten tiny teeth, and bigger eyes. They are the size of a grape, at 22mm in length. 

This is a big week for your baby, the four chambers of the heart have formed. What’s more is that you’ve gained a new organ, too. The placenta is devloped and takes over in caring for your baby. 

During this time, moms-to-be typically experience intense food cravings as well as intense food aversions. What you used to love is on a do-not-buy list and what you never thought you wanted is all you want. Typical food aversions during pregnancy include meat, dairy, eggs, spicy foods, and coffee. 

Most moms are incredibly exhausted during this period. Don’t be ashamed to nap. In fact, moms need extra sleep. Find a sleeping position that is suitable for you. For now, sleeping on your stomach is still possible so if that’s your go-to position, take advantage of it while you can because your big baby bump is on the way. 

If you experience lower back pain, vaginal bleeding, or constant itching during this time, contact your doctor. 

Week 10

This is when doctor’s visits get really fun. You can begin to hear your baby’s heartbeat during a prenatal visit and get an NIPT test which rules out Down syndrome and other conditions. 

Your baby weighs 1.3 ounces, and your baby’s vision is fully formed. The cornea, iris, pupil, lens, and retina are all there. What’s more, is that your baby’s teeth are hardening and connecting to the jaw bone. However, you won’t actually see these teeth until they are six to 10 months old. 

As for the mother’s body, last year’s jeans are getting a little tighter. Weight gain and bloating are normal around this week and it’s a good idea to begin investing in maternity clothes with stretchy waistbands. 

Other changes include visible veins along the chest, breasts, and belly. Your body is working hard and producing more blood which means your veins are more visible. However, these veins aren’t permanent and usually disappear after childbirth. 

At nine of 10 weeks, pregnant moms experience their worst bout of morning sickness. This is when hCG levels are the highest. But you’re almost through the tough part. At 11 weeks, hCG levels begin to fall and by 15 weeks you should feel considerably less nauseated. 

Week 11

Your baby is looking less amphibian now. It’s also the size of a fig. The webbing between the toes and fingers has disappeared and your baby is also more complete, with all organs beginning to function. After week 11, your baby will have genitals

As for symptoms, they mirror the last two weeks. Hang in there, though. You’re almost done with the first trimester. And remember that you aren’t alone. Approximately 60 percent of women experience food aversions during pregnancy. And while you may be extremely fatigued now, most women feel a burst of energy when they start their second trimester.

You may notice your skin is changing. And no, it’s not a baby glow. Acne, stretch marks, rashes, and melasma are all beginning to show up. Take care of any skin issues by visiting your doctor or seeking natural and holistic measures. 

Mothers should begin eating calcium-rich foods while pregnant, which supports the baby’s bones, teeth, nerves, and muscles. On average, women need 1,000mg of calcium a day. Some of this can be absorbed from a prenatal vitamin

Week 12

During week 12, your chance of having a miscarriage significantly drops, which is why most moms announce their pregnancy around this time. 

Your baby is the size of a lime, and your uterus has grown to be the size of a grapefruit. Your baby is also on the move, curling their hands to make fists and curling their toes as well. 

Symptoms for moms remain the same. Some moms begin to feel more dizzy around this week due to the cardiovascular system going through some immense changes. Your heart rate increases and pumps more blood per minute, leading to lightheadedness and dizziness. Another symptom is shortness of breath, which is fairly common during the entire length of the pregnancy moving forward. Mothers need more oxygen during pregnancy. However, if it is accompanied by chest pain, severe shortness of breath, or asthma, contact your doctor right away. 

Week 13

Your baby is the size of a peapod, and you’re one week away from your second trimester. 

Just like your frequent bathroom runs, your baby has also started to urinate. By swallowing amniotic fluid, they recycle the fluid every few hours. They’ve also started to poop.

In week 13, your breasts have started to make colostrum, which is the fluid that feeds your baby a few days after birth. It’s the fluid before milk, and it’s incredibly nutritious for the baby. 

During this week you may begin to experience less food aversions, a returning appetite, and more energy

Week 14

You’ve finally made it to the second trimester! Here’s where you’ll begin to really show during your pregnancy and begin feeling like yourself again. 

This is usually the time when you’ll begin getting ultrasounds, although some women get them in the first trimester. 

Your baby is the size of a lemon and weighs 3.28 ounces. They’ve begun to make facial responses like squinting and frowning. They’re even a little hairier as their hair follicles have started to sprout

As for symptoms, what symptoms? Many moms report feeling more energetic, less queasy, and more comfortable with being pregnant. 

Returning appetites are a great sign and aid in energy levels, which many moms feel around week 14. Make sure to eat an extra 300 to 350 nutritious calories for your baby during your second trimester. 

During this time, participate in exercise since your energy and mood is better. Exercising can promote better sleep, reduce discomfort, and lower pregnancy complications

Week 15

Get your gender reveal party ideas ready, this is the week you might be able to tell if you’re having a boy or girl. However, most doctors wait until 18 to 21 weeks for an accurate look. 

This is also a good time to begin brainstorming baby names to get you excited for the following months. 

Since your baby is the size of an apple now, you’ll begin to clearly see your baby belly. For first-time moms, they usually show later, however. 

As for your baby, at week 15, they are forming taste buds and their legs are growing longer

Week 16

Acne-be-gone! This is the time when your pregnancy glow begins to finally show up. You may also be introduced to a new laundry list of symptoms. 

Round ligament pain impacts some women as the growth of the uterus impacts the ligaments that support it. The pain feels like a sharp, stabbing pain, which can alarming for moms. Rest, stop what you’re doing, and the pain should ease up. If the pain doesn’t go away, contact your doctor. 

Your baby is the size of an avocado now, and this is when moms begin to feel back pain. The uterus is expanding, the baby is growing, and your back is putting in extra work. Doing gentle workouts like walking or yoga can ease this pain. Some moms even book a pregnancy massage, which can reduce any tension in the back. 

Another new symptom is pregnancy fog or pregnancy brain. Some women experience forgetfulness during pregnancy. Researchers aren’t entirely sure why but we can assume it’s due to stress or anxiety. 

Week 17

Your baby is the size of a turnip at this point and guess what, it can hear you. The baby will hear your heartbeat and breathing. It doesn’t hurt to talk to the baby, either. 

Begin sleeping on your side during your second trimester and it puts less pressure on the veins, ensuring better blood flow. 

During week 17, some moms report blurry vision or dry eyes, too. Vision changes are common during pregnancy due to your hormones going haywire as well as your metabolism and blood circulation being altered.

As your belly grows, stretch marks may begin to appear. However, most of them fade after childbirth. 

Week 18

During this week your baby is the size of a bell pepper and is 8.7 inches in length. This is when the baby’s lungs are beginning to develop. They appear as small tubes and respiratory sacs. 

In week 18, leg cramping can begin as well as swelling. This is due to your legs working harder and carrying more weight. In order to ease any pain, apply a heating pad to your legs. Use this time for some TLC — take a warm bath, take a short walk, and stay hydrated. 

Week 19

Your baby’s the size of a tomato during this week and they have a few new characteristics. Along with unique fingerprints, your baby is also developing a sense of smell, taste, vision, and touch

This is the week your baby belly might explode in size. Shorter women have bigger bellies, as do first-time moms, or moms who are having twins. Whatever the case, embrace the bump. 

Week 20

You’re pretty much halfway through your pregnancy during this week. Itchy skin, restless sleep, long nails, and thicker hair may all be symptoms you begin to feel during this week. 

If you feel your banana-sized baby move rapidly and suddenly, that’s probably because it’s having a hiccup. Usually, moms feel a baby’s hiccup around 16 to 22 weeks. 

Week 21

Your baby is the size of a carrot in week 21 and is beginning to suck their thumb

As for moms, they report feeling more clumsy this week. Scientists believe that a growing belly can throw moms off-kilter, and they can feel more off balance. Be careful not to fall, as this can harm the baby, so avoid any tricky chores and walk slowly on uneven ground. 

Since early in pregnancy, women experience Braxton Hicks contractions which are uterine contractions that are painless and irregular. Most women don’t feel them, but at 21 weeks, it’s common to feel them. They are totally harmless and are considered “practice” contractions, but some moms may be worried they are going into preterm labor. Call your doctor if the contractions are regular and coming on more frequently. 

Week 22

At 11 inches, your baby resembles a sweet potato during week 22. They have hair on their heads, and they are beginning to develop baby fat.

As for continuing side effects for moms, acne, spider veins, diarrhea, and swelling are common during week 22. 

Week 23

Sized like a mango, your baby can hear you and your partner’s voice. Research has shown that babies recognize their mother’s voice while inside of her. You can also begin playing music or singing to your baby as well. 

You may begin to feel your baby move more now as well. The feeling is stronger and more frequent. 

During week 22, you may have the linea nigra, a dark vertical line that goes down the woman’s pregnant belly. This is caused by high hormone levels that change your skin color. 

Week 24

Your baby, which is the size of a corn on the cob, is growing plumper by the week. And with the second trimester almost finished, soon you’ll be able to meet your chubby little darling. 

Of course, pregnancy symptoms still loom. You may be experiencing hyperpigmentation, hives, or bumps. Some women also experience spotting due to changes in the cervix. While it’s typically harmless, visit your doctor if the bleeding is heavier than usual. 

Your belly is pretty large by now, as the top of your uterus is now resting above your belly button. 

Week 25

Your baby is the size of an eggplant and over a foot long during week 25. 

Week 25 comes with some frustrating side effects, however. Hemorrhoids are one of them. The majority of women experience itchy veins in the rectum due to the uterus putting pressure on the area. Many women are also constipated during pregnancy, which can induce and aggravate hemorrhoids as well. The main prevention and treatment is to increase fiber and fluid intake. Aim for eating fruits, veggies, and whole grains. 

Heartburn, snoring, leg swelling, and tingling hands are other not-to-pleasant side effects of week 25. 

Week 26

Your baby is the size of a cucumber, and they’ve started to inhale and exhale amniotic fluid, which helps them establish lung development. 

During this time, your baby will begin to feel a little claustrophobic in the uterus, which doesn’t mean it’s ready to come out, it just means you may feel its kicks and punches a little bit more. 

At 26 weeks, you’ll begin to notice your belly button becoming an outie, if it wasn’t already. You may also experience insomnia or have a restless sleep due to your baby’s midnight gymnastics. 

Week 27

You’re almost done with your pregnancy. Yes, you’re actually almost ready to get this baby out! This is the last week of the second trimester, entering into the last and final trimester. 

During week 27, you may experience something called edema, which is when fluid builds up in the body’s tissue due to increased blood pressure. Your shoes may be tight, your rings may no longer fit, and you’re feeling an increased puffiness. 

While some puffiness is normal, excessive swelling can be due to preeclampsia, which is also accompanied by high blood pressure, severe headaches that don’t go away, pain below the ribs, and protein in the urine. Visit your doctor right away if you’re concerned in order to ensure the safety of yourself and your baby. 

As for your baby, they are the size of a head of cabbage and only grow more by the minute. 

Week 28

The week is finally here, the first week of your last trimester. With the end comes more discomfort, however. 

Where the second trimester was more comfortable, the third comes with swollen limbs and backaches that don’t go away. 

You may also notice yellowish leakage coming from your breasts. Remember colostrum from week 13? That’s the first fluid your body will make for your baby, also known as “liquid gold.” 

During this time, snack on iron-forward foods like chicken, beans, spinach, tofu, and beef. 

In the 28th week, doctors will suggest monitoring the baby’s kicks and movements. You’ll usually feel 10 movements within two hours. Doctors suggest counting the kicks, rolls, or flutters within those two hours. Once you begin to feel the movement, write down the time, and then conclude the time when the movements stop. 

In this trimester, your baby’s brain will triple in weight and develop. Additionally, your baby is the size of a very large eggplant. 

Week 29

From head to toe, your baby is roughly 15 inches long — the size of a butternut squash. And the baby is using a lot of calcium for bone strength, approximately 250 milligrams. Make sure you’re taking in sources of calcium to support you and the baby. 

During this time, your doctor will continue screening for preeclampsia and gestational diabetes during prenatal visits. 

Week 30

In week 30, your baby begins producing blood cells, which means they can survive on their own once they are born. 

As for mom, many of those pesky symptoms have returned. The need to pee, heartburn, tender breasts, and exhaustion are common. Increased estrogen also leads to brown discharge, which is just old blood. It’s usually nothing to worry about but visit your doctor if you are concerned. 

Week 31

As big as a coconut, the baby at 31 weeks will usually be sleeping more, giving you some better shut eye as well. Other babies may keep you up at night. All of the week-by-week process and symptoms may be different for every baby. Just like they are unique after birth, they are unique in the womb as well. 

During this time, you can prepare by packing your delivery bag for the hospital and prepare your birth plan. 

Week 32

The baby, which is the size of a big bunch of celery, will begin to shift in the womb around this time and in the coming weeks, getting prepared for birth with its head down. If you have your baby now, at week 32, the outcomes are healthy and don’t have long-lasting issues. The baby would be born moderately preterm but would still be safe. 

During this time, your baby has begun to store iron, calcium, and phosphorus for when they are born. External genitalia for boys and internal genitalia for girls have fully formed at this moment as well. 

As for the mom, the belly will begin to feel tight and heavy.

Week 33

The baby is the size of a pineapple and can differentiate day versus nighttime. The baby has also developed its own immune system so it can fend off germs when out in the real world. 

In week 33, some women report feeling numbness in their fingers, wrists, and hands. This could be carpal tunnel syndrome, which happens when a nerve in the hand is compressed due to the swelling of pregnancy. While carpal tunnel can appear anytime in pregnancy, it’s usually common when the swelling is the worst in the third trimester. 

Other forms of swelling include a swollen labia. Increased blood flow as well as pressure can contribute to a larger labia. 

Week 34

Your baby is now the size of a cantaloupe and is curled in a literal fetal position. There’s less room in the uterus now so you’ll feel every small movement. 

You’ll probably still feel the same symptoms that you’ve been feeling. Breathlessness, heartburn, and frequent urination. Your baby is pushing upwards which puts pressure on the lungs. 

By now, educate yourself on the signs of labor. Cramping, contractions, backache, fluid coming from the vagina, and when the mucus plug comes out. The mucus plug covers the cervix and is otherwise known as when your “water breaks.” 

Week 35

Your baby is still protected by amniotic fluid, but the fluid will decrease slightly until the day you give birth. 

In the third trimester, mothers may experience headaches due to tiredness, hunger, or dehydration. Vision changes can also lead to headaches. 

Many women feel excessively warm while pregnant, like having a hot flash. This is because your body is working hard. It’s carrying around extra weight, your heart is working harder, and you have more blood circulating. As a result, the skin feels warm. Hormonal levels can also contribute to drops in estrogen, which contribute to hot flashes. 

Week 36

During this week, your baby is the size of a head of romaine, and it’s in the position for birth. You’ll be visiting the doctor weekly at this point to ensure your weight and blood pressure are healthy. 

At 36 weeks, your baby will drop into your pelvis. Walking will be uncomfortable and you may feel vaginal pressure. This should alleviate breathing issues, however. 

If you have your baby at 36 weeks, this is considered a late preterm baby. Your baby’s lungs are fully formed and are ready to breathe outside of the womb. The bones are hardened and will continue to harden. The baby is also shedding the substance that protects their skin while in the womb. What happens to the shedding? Well, the baby swallows it, which turns into the baby’s first poop called meconium. 

Week 37

At this point, you could go into labor at any moment as you are officially nine months pregnant. Your doctor will continue to check your cervix to see if it has dilated or softened, which are signs of labor. 

You’ll probably feel your baby tossing and turning around this time as they are preparing for birth by breathing in the amniotic fluid, wiggling their limbs, and moving from side to side. 

Week 38

During this time women typically get a burst of energy. The baby, is indeed, coming. And its currently the length of rhubarb. All that preparation is coming to fruition in an exciting way. 

Some women experience something called “lightening crotch,” which is a phenomenon of a jolting sudden pain in the pelvic area. 

Another thing to expect is more vaginal discharge that is creamy and white. Any green or sudden bleeding should be checked out by a doctor. 

With a few weeks left to go, the belly is hard and tight. Many women describe it as having a bowling ball between your legs. 

Week 39

Your baby is now “full term” and continues to build up fat, averaging 7 pounds and resembling a mini watermelon.

Keep monitoring the baby’s movements during this time and contact your doctor right away if anything has changed. 

An unfortunate symptom of 39 weeks is the presence of diarrhea, which could potentially be a sign of early labor. However, this isn’t scientifically researched. If you have diarrhea, make sure to stay hydrated. 

Week 40

At this point, you’re probably ready for your baby to make their grand entrance into the world. Naturally inducing labor isn’t a proven science, but some people suggest taking a slow walk or having gentle sex (don’t worry, you won’t hurt the baby). 

A doctor can check to see if your cervix is thinning and softening, eventually opening for labor. However, just because your cervix is getting ready for birth doesn’t mean it happens right away. It may take days for the labor to be induced. 

By this point, you’re probably used to having Braxton Hicks contractions so you can probably differentiate them from labor pain. Braxton Hicks are no painful and they are irregular. Whereas contractions are painful, grow in intensity, and are constant. 

At this point in your pregnancy, all you can do is wait. Relax, make sure your delivery bag is packed, finalize going over names, and get ready to welcome your baby. 

Week 41

At 41 weeks, not giving birth yet is still considered normal. Most doctors select a due date of 40 weeks, however. A late-term pregnancy can be due to miscalculation, a first-time pregnancy, being overweight, having a boy, or having previous late-term pregnancies. 

Your doctor will also go over options for inducing labor. Approximately one in five births are induced. The options for induction include medication, a suppository, breaking your water, or using a catheter to help dilate the cervix. 

As for symptoms during weeks 41 and 42, expect all of the above. Swelling of the legs, bleeding gums, heartburn, backache, headache, and dizziness can all be expected when having a late-term pregnancy. 

Week 42

At 42 weeks, your baby is considered “late-term.” After this week, if your baby isn’t born, your doctor will recommend inducing labor since it may lead to complications the longer you wait. 

Once born, your baby may look strange, with a funny head shape, and different skin color. All babies, no matter what ethnicity, have a red and purple skin tone that changes to pink and red in a day after birth. Eventually, they grow into their skin tone and facial features, resembling the mother and father. 

The average weight of a baby in the United States is seven to eight pounds and 20 inches but babies born at 42 weeks are usually larger. 

For now, the seemingly short journey of pregnancy has ended and the long journey of life has begun. 

 

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