Note: Don’t fret if your prenatal milestones fall earlier or later than what this guide suggests. “We all progress through pregnancy in our own unique way,” says Amy L. Stenson, MD, MPH, assistant professor at Oregon Health & Science University in Portland. “There are many ways to have a healthy, happy pregnancy. If you have a concern, discuss it with your health care provider. … [She] can evaluate things and either reassure you or help you get back on track.”
Weeks 1-2: During the first weeks of pregnancy, there’s technically not a baby in your belly—but there will be. Doctors calculate due dates by counting 40 weeks (or 280 days) from the first date of the last menstrual cycle.
Week 3: Congratulations—you’re pregnant! (Although you don’t know it because you haven’t yet missed a period.) Right now, your wee one is a cluster of cells roughly the size of a pinhead, but she’s growing fast. You won’t find out if the bun in your oven is a boy or girl until much later, but baby’s sex is determined as soon as the egg has been fertilized.
Week 4: You’ve been stood up for your monthly date with menstruation. A lack of bleeding is the first tip-off that something’s up. On the inside, your amniotic sac and placenta are starting to form, but you aren’t the only one changing. Your babe’s nervous system—which includes her brain and spinal cord—is already developing.
Tip: As soon as you find out you’re pregnant, call your OB/GYN or midwife to schedule your first visit—sometime between 6 and 10 weeks. If you’ve had problems with miscarriage or abnormal pregnancies, Stenson says it’s all the more important to let your doctor know right away that you’re expecting.
Week 5: The makings of a tiny heart are in the works. If you have an ultra-sound, you might be able to see it beating as early as week 5 or 6. With a baby on board, you’ll need to pay closer attention to what you put on your plate. Stenson advises, “Half of what we eat should be fresh fruits and vegetables. The other half should be primarily lean proteins, healthy fats and whole grains.” She also stresses drinking plenty of water and eating low-mercury fish, or other sources of omega-3 fatty acids. But it’s OK to treat yourself, too: “I believe that it is important to eat a little bit of what we love, like dark chocolate or ice cream.”
You should be taking a prenatal vitamin to help fill any nutritional gaps in your diet. Look for an option that includes iodine and DHA for brain development.
Week 6: Most moms-to-be will experience nausea that unfortunately rears its ugly head at all hours despite what its nickname implies. If you find yourself in the queasy camp, stay hydrated, and try grazing instead of gorging to keep morning sickness in check. (Take heart, nausea should disappear by week 13.)
It’s perfectly OK if being a mama-to-be isn’t as enjoyable as you thought it would be. “Pregnancy is a natural and beautiful part of life, but it is also taxing,” says Stenson. “Some women feel like an ‘earth goddess,’ and others feel as though they’re carrying a parasite. These are both normal feelings and don’t affect the bonding that happens after the baby is born.”
Week 7: With swollen, achy breasts and an expanding uterus, you might notice your clothes fit a little differently. It’s probably getting harder to resist the snooze button, and you’re making frequent trips to the ladies room.
By the end of this week your budding sprout will have doubled in size to be an impressive half-inch. Her legs and arms are growing, her lungs are forming, and she has kidneys. She’s also generating around 100 brand-new brain cells every minute!
Week 8: It’s time for the first of many prenatal checkups with your care provider. Set aside plenty of time because it will be one of the longest—and, yes, you can expect to slip your feet into the stirrups for a physical exam. From here on out, you’ll be seeing doc every four weeks until closer to D-day.
Week 9: Your 1-inch bambino is looking more like a baby. (Don’t worry about the webbing between her fingers and toes; it will disappear soon enough.) She’s also building muscle and using it to make her first movements—but you won’t feel those shimmies and shakes just yet.
Speaking of getting a move on, exercise is important for moms-to-be to help regulate weight gain and stave off constipation. Talk to your practitioner to find out if you should make any adjustments to your prebaby workout.
Week 10: The first ultrasound gives a peek into your womb. Listen up for baby’s heartbeat, also known as the sweetest sound you’ve ever heard.
Seeing your peanut for the first time might bring out your emotional side, but it’s not the only thing cuing the waterworks. Whether you find yourself crying during a diaper commercial or getting hot-headed when the grocery store is out of kiwis, it’s all normal. Mood swings typically kick in between weeks 6 and 10 and tend to stick around for the duration.
Week 11: You might notice your appetite return along with some unusual cravings. Feeling famished? That’s just your body’s way of ramping up energy stores for you and your growing babe. Don’t double up on your lunch order, though. You need to add only an extra 300 calories to your daily diet, the equivalent of a healthy snack.
Tip: Between weeks 11 and 15 you’ll have two tests: a nuchal translucency screening (NTS) and a blood test to find out your baby’s risk of Down syndrome and other chromosomal disorders.
Week 12: Your amazing little one has been sprouting new body parts at an impressive rate. Her kidneys, liver and other organs are doing their jobs. Her head is about half her size, so she still has a lot of growing to do.
Week 13: You’re a third of the way to meeting your mini! The next phase of pregnancy is widely considered the sweet spot. Nuisances like morning sickness and exhaustion will fade, and you’ll feel more like your old self. Make the most of this time by tackling nursery projects and celebrating the big news! That’s right: Now that the threat of miscarriage has taken a nosedive, you can spread the word.
Week 14: Your uterus is rising into your lower abdomen instead of giving you an awkward paunch down in your pelvis. Now that you’re (finally!) starting to show—in an adorable way—you can flaunt your fertile figure!
Week 15: Baby is growing hair—and not just on her head! She’s covered in a thin, soft fuzz (like a peach) called lanugo, which keeps her warm.
Week 16: Beginning this week, your peanut can hear her mama’s voice. Studies show that when mothers sing to their unborn babies, the infants can later recognize the tune outside of the womb, so don’t be shy about belting out those lullabies.
Week 17: Your little one is packing on the ounces. (She’ll weigh about 3-5 at this point.) Now that your baby is getting bigger, you should be, too. The second trimester is when you’ll notice the numbers on the scale climb. Remember: Slow and steady weight gain is best. Aim for roughly 1 pound per week.
Week 18: Sometime between weeks 18 and 20, you’ll have your anatomy ultrasound. You’ll see baby looks much more human now—even though she’s only about 5 inches from head to rump. If your little one cooperates, you could also find out if you’re having a boy or a girl.
Week 19: Right about now your baby is getting coated with vernix, a greasy white substance that will protect her skin while she soaks in her amniotic bath.
Week 20: You’ve reached the halfway mark. Maybe that’s why you’re feeling butterflies in your stomach—or is it gas? Actually, that fluttering is your baby moving inside you! Some veteran moms can feel movements as early as week 16, but first-timers might not recognize the kicks until week 25.
Week 21: Baby’s tiny taste buds have formed. Odds are your little one will get a taste of whatever’s on the menu this week. Research shows that, after birth, babies are keen to eat foods they were exposed to in utero. So if you want your little lady to love her veggies, give her a head start.
Week 22: Now that your protruding belly is pushing your center of gravity forward, it’s pulling your lower back right along with it. The pregnancy hormone relaxin isn’t helping matters as it relaxes your ligaments—which is good for birth but not so good for back pain.
Week 23: That pipsqueak inside you has finally hit 1 whopping pound. She’s strong enough to grip things, including her umbilical cord. She also has eyelashes and eyebrows, though they’re bright white. (Ignore all thoughts of Benjamin Button; the final color will show up later on.)
Week 24: As your skin stretches, the tissue underneath can tear, causing red or purple streaks moms-to-be know all too well as stretch marks. Genetics is a major factor in whether you’ll earn a few tiger stripes, but it doesn’t hurt to slather on the moisturizer.
Week 25: Experts advise pregnant women sleep on their left side, but with your bump taking up more real estate in bed, it can be hard to get comfortable. Try supporting your belly with a pillow underneath it.
Week 26: Another sleep thief to look out for: leg cramps. These pesky, not to mention painful, spasms that shoot up and down your calves are known to keep expectant women up at night, so stretch your calf muscles before hitting the hay.
Week 27: Baby and belly aren’t all that’s growing these days. Your feet are probably looking larger, too. Some moms-to-be go up a full size.
Week 28: Raise a glass of sugary orange liquid to the next trimester! You’ll take the glucose challenge screening test between weeks 24 and 28. Cheers!
Tip: Get ready for more frequent dates with doc. Plan on stopping by every two weeks between weeks 28 to 36 and then weekly until baby arrives.
Week 29: Your due date is still months away, but now is the time to sign up for a childbirth class and write your birth plan. Your mini is closing in on 3 pounds. Now that she’s bigger, it’ll be hard to miss those elbow jabs. Her body won’t grow much more lengthwise; instead it will focus on gaining weight.
Week 30: Your old pals from the first trimester (fatigue, the constant need to pee, etc.) are back, and unfortunately they’ll be hanging around.
Week 31: Baby’s brain is growing at warp speed. She can blink her eyes, and her nose is ready to sniff as soon as she isn’t submerged. (That means your scent will be one of the first she smells!) Her bone marrow is busy making red blood cells—a crucial step toward being able to survive on her own.
Week 32: The end of pregnancy can be quite literally tough to swallow if you come down with a wicked case of acid reflux or GERD. You might also have trouble catching your breath because your uterus needs more room, which leaves your lungs feeling crowded.
Week 33: Around the final weeks of bumphood you’ll probably get the urge to deep clean the house, organize the closets, and stock the pantry and freezer. Welcome to the nesting phase!
Week 34: Those varicose veins sprawling across your legs could make an unwelcome appearance south of the border, where they’re unaffectionately known as hemorrhoids.
Tip: It’s a good time to pack your hospital bag. For a list of what you’ll need, visit pnmag.com/packinglist.
Week 35: Braxton Hicks contractions are the body’s way of rehearsing for delivery day. You’ll know they’re the real deal if they come at regular intervals, increase in intensity and frequency, and don’t slow or stop when you change positions.
Week 36: Baby’s bones are getting stronger, so don’t skip out on calcium-rich foods. Your aching bones could use the support, too.
Week 37: At your weekly visits, your health care provider will be checking you for signs of labor—including how much your cervix has opened (dilation) and thinned (effacement).
Week 38: Your babe is considered full term at the end of this week. She’s dropping lower into your pelvis to get into position for the big day, which means you’ll feel like you can finally breathe again. Get ready to waddle your way to the finish line!
Week 39: Vaginal discharge will be amping up its flow. Look out for the mucous plug, a sign that labor isn’t far off.
Week 40: The moment you’ve been waiting for is here … and soon your baby will be, too.
At your own pace
Don’t fret if your prenatal milestones fall earlier or later than what this guide suggests. “We all progress through pregnancy in our own unique way,” says Amy L. Stenson, MD, MPH, assistant professor at Oregon Health & Science University in Portland. “There are many ways to have a healthy, happy pregnancy. If you have a concern, discuss it with your health care provider. … [She] can evaluate things and either reassure you or help you get back on track.”