What size is a fetus at 1 month?

• Pregnancy

Looking for a week-by-week guide to pregnancy? You're in luck! We've got loads of expert-approved info about each week and trimester, including what's up with your growing baby and what changes to expect for yourself.

You'll find stunning fetal development videos, thousands of articles, and helpful tools like our Due Date Calculator and Baby Names Finder. Meet other parents-to-be in our online community, and get all of this and more in our free pregnancy app. Dive in, and congratulations!

First Trimester

It's a potentially life-changing week. You'll ovulate, and if egg meets sperm, you'll be on your way to pregnancy!

Your baby is a tiny ball – called a blastocyst – made up of several hundred cells that are multiplying quickly.

Deep in your uterus, your baby is an embryo made up of two layers, and your primitive placenta is developing.

Your tiny embryo is growing like crazy, and you may be noticing pregnancy discomforts like sore breasts and fatigue.

Your baby's nose, mouth, and ears are beginning to take shape. You may be having morning sickness and spotting.

Your baby – still an embryo with a small tail – is forming hands and feet. Your uterus has doubled in size.

Your baby is constantly moving, though you can't feel it. Meanwhile, you may be making decisions about prenatal tests.

Nearly an inch long now, your baby is starting to look more human. You've probably noticed your waist thickening.

Your baby has finished the most critical part of development! Organs and structures are in place and ready to grow.

Your baby's hands will soon open and close into fists, and tiny tooth buds are appearing underneath the gums.

Your little one's teeny toes can curl, her brain is growing furiously, and her kidneys are starting to excrete urine.

It's the last week of the first trimester! Your baby now has exquisite fingerprints and is almost 3 inches long.

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Second Trimester

Your baby's tiny features are making different expressions. And you may be feeling more energetic and less nauseated.

Your baby can sense light and is forming taste buds. Have a stuffy nose? It's a surprising pregnancy side effect.

Get ready for a growth spurt. In the next few weeks, your baby will double his weight and add inches to his length.

Your baby's skeleton is changing from soft cartilage to bone, and the umbilical cord is growing stronger and thicker.

Your baby's genitals are developed enough to see on an ultrasound. Hungry? An increase in appetite is normal now.

Go ahead and sing: Your baby may be able to hear you! And if your sides are aching, it could be round ligament pain.

Congratulations, you're at the halfway mark in your pregnancy! Your baby is swallowing more now and producing meconium.

Feeling your baby move? Those early flutters will turn into full-fledged kicks. Cool fact: She has eyebrows now!

Your baby is starting to look like a miniature newborn. And your growing belly may be turning into a hand-magnet.

When you're on the move, your baby can feel the motion. Pretty soon, you may notice swelling in your ankles and feet.

Your baby is long and lean, like an ear of corn. And your growing uterus is now the size of a soccer ball.

Your little one is starting to add some baby fat and grow more hair. Your hair may be looking extra lustrous, too.

Your baby is inhaling and exhaling small amounts of amniotic fluid, which is good practice for breathing.

Feel a tickle? It may be your baby hiccupping. He's also opening and closing his eyes and even sucking his fingers.

Third Trimester

Welcome to your last trimester! Your developing baby's eyes may be able to see light filtering in through your womb.

Your baby's muscles and lungs are continuing to mature, and her head is growing to make room for her developing brain.

Your baby now weighs almost 3 pounds. Meanwhile, you may be battling mood swings, clumsiness, and fatigue.

Your baby's strong kicks might be keeping you up at night – and you may be feeling Braxton Hicks contractions, too.

Your baby is plumping up! Meanwhile, your expanding uterus may cause heartburn and shortness of breath.

With your baby now weighing a little over 4 pounds, you might be waddling – and having trouble getting comfy in bed.

Your baby's central nervous system and lungs are maturing, and dizziness and fatigue may be slowing you down.

Your baby is too snug in your womb to do somersaults, but you'll still feel frequent – if less dramatic – movements.

Your baby is gaining about an ounce a day. You may feel her "drop" down into your pelvis as you approach your due date.

Your baby's brain and lungs are continuing to mature. You may have more vaginal discharge and occasional contractions.

Your baby has a firm grasp, which you'll soon be able to test in person! Meanwhile, watch out for signs of preeclampsia.

Your baby is full term this week and waiting to greet the world! If your water breaks, call your healthcare provider.

Your baby is the size of a small pumpkin! Don't worry if you're still pregnant – it's common to go past your due date.

As cozy as he is, your baby can't stay inside you much longer. You'll go into labor or be induced soon.

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