A Week-by-Week Guide to Pregnancy

Pregnancy can be overwhelming, especially if it’s your first time. But no need to fear––we’ve compiled a guide for you! Read on to learn how baby is growing, what your visits to the doctor may be like, and what you can be doing at home to stay proactive and feel your best. You’ve got this!

Weeks 0-4

  • What to expect: During these initial weeks, you might not even realize you're pregnant, but you'll likely experience symptoms of early pregnancy, such as breast tenderness, nausea, vomiting, and fatigue, as well as your first missed cycle. Implantation bleeding (light bleeding that can sometimes occur when a fertilized egg finds a home on the uterus) may also occur, which is typically lighter and shorter than a regular period; however, some women mistake this for their period, and may not realize that they are pregnant until their next missed cycle.
  • What you can do: Call your OB/GYN and set up an appointment to be seen. Take a daily prenatal vitamin if you aren’t already. Look for vitamins containing at least 400 mcg of folic acid; and yes, gummies are acceptable! If you’re taking any other medications, call the prescribing doctor to discuss pregnancy safety and whether or not you should discontinue use. Stick to mocktails only, and discontinue any smoking if that’s a habit you partake in.
  • Baby’s growth: Baby is just forming and is more or less a small collection of cells. The placenta is also beginning to form. By the end of the 4th week of pregnancy, baby is about 2mm in size, which is similar in size to a sesame seed.

Weeks 4-8

  • What to expect: Women will typically have their first visit with their OB/GYN during this time, so if you haven't scheduled one, do so ASAP. A pap smear may be performed and your health history, including current medications and prior pregnancies, will be reviewed. A dating ultrasound (to estimate the due date and gestational age (or how far along the pregnancy is) will either be performed or will be scheduled. You also may begin to notice some of the common discomforts of the first trimester of pregnancy; these include nausea and vomiting, fatigue, breast tenderness, dizziness when standing, and occasional mild headaches.
  • What you can do: If you’re feeling nauseous, stick to bland foods and smaller portion sizes. Ginger (ginger ale, ginger tea…) can help settle the stomach, as well. If your prenatal vitamins aren’t helping things, switch to taking them at night before bed or try a gummy version. And lastly… drink A LOT of water! It helps everything in pregnancy. Seriously.
  • Baby’s growth: The heart is already beating (and can be seen on ultrasound!) and the skeleton, brain, and vital organs are beginning to form. Baby is about the size of a bean, or close to 1 inch.

Weeks 8-12: Congratulations - you made it through the first trimester!

  • What to expect: A dating ultrasound will be performed during these weeks (if it’s not already been done) in order to solidify the due date.
  • What you can do: Pay attention to your nutrition. Are you eating for two? Have you stopped exercising? On average, women only need about 300 more calories a day during pregnancy. Unfortunately, that is not eating for two. Depending on your initial weight, your provider can give you an estimated weight gain goal for your entire pregnancy. It’s good to be aware of these recommendations early on in order to tailor your diet and exercise appropriately. Exercise in pregnancy is encouraged (just avoid lifting heavy weights); you can find exercise recommendations and guidelines here. Keep in mind that everyone's body is different!
  • Baby’s growth: Around week 12, baby's heart rate can be heard on Doppler (a device used to measure fetal heart tones). Bones are starting to harden and external genitalia begin to form. The sex will typically be visible on ultrasound at around 14-20 weeks. Baby will be about 8 centimeters, the size of a small lime.

Weeks 13-20

  • What to expect: While most of the early symptoms of pregnancy (fatigue, breast tenderness, nausea and vomiting) begin to improve after the first trimester, nausea and vomiting will occasionally continue on through about 18 weeks (for those particularly lucky gals). A blood draw for genetic testing may be done during this time; the type of genetic screening performed depends on your own personal and family history, age, and what your provider advises. Genetic testing is not required, but can be a helpful test to screen for any fetal abnormalities, such as a neural tube defect (like spina bifida), or down syndrome. These tests can occasionally be costly, especially if they aren’t covered by insurance. Because of that, some of the more in-depth genetic testing is only offered to patients at a higher risk for genetic abnormalities (like age over 35 or a personal or family history of a genetic disorder).
  • What you can do: The second trimester is typically when moms feel their best. Take advantage of this increased energy and get your planning, exercising, and nursery decorating on.
  • Baby’s growth: Baby can begin making faces (like a smile!) and sucking his/her thumb. Also neat - the ability to hear is beginning to solidify. Baby doubles in size in this period, growing from about 4 inches to around 8 inches, or about the size of a large grapefruit.

Weeks 20-23

  • What to expect: An anatomy ultrasound is performed around this time (which looks at all the parts of the baby). This is usually when women begin to feel baby move. While the nausea and vomiting may begin to fade away, other symptoms will likely take their place-- wrist pain, heartburn, and constipation are common complaints in the second trimester.
  • What you can do: Natural fluid retention can cause carpal tunnel syndrome, so you may experience wrist pain and tingling in the hands and fingers. Sleeping in wrist splints (so fun, right?) can help with this. For heartburn, avoiding fried, spicy, and fatty foods, as well as cutting back on portion sizes, can help. After a meal, make sure and stay standing or sitting upright for about 30 minutes, or risk that stomach acid coming back up. If you’re still having trouble with heartburn, talk to your provider about appropriate over-the-counter medication management. Last, but certainly not least: constipation. The best thing to help that? Water. Those 8 full glasses a day are the miracle medicine of pregnancy! If you’re still suffering from infrequent bowel movements, a stool softener, like colace (available over the counter) can be helpful.
  • Baby’s growth: By the 23rd week of pregnancy, baby has typically reached 1lb in weight, about the size of an eggplant.

Weeks 23-27

  • What to expect: Between 26-28 weeks, a gestational diabetes test is typically performed (you’ll down a super sweet drink and get your blood drawn an hour after). If you are a negative blood type, you may also receive a shot of rhogam, a medication used to help prevent your blood from creating antibodies to baby’s blood. As you near the end of the second trimester, you may notice some new pregnancy discomforts. Swelling of the ankles and feet, especially at the end of the day, is common.
  • What you can do: If you’ve got a case of puffy feet, kick your feet up whenever you’ve got a chance. Compression stockings can also be helpful in reducing swelling, as well as cutting back on salt intake. As always, keep drinking that water! If the swelling is noticeable in the legs or face, let your provider know.
  • Baby’s growth: By the end of the second trimester, your baby is close to 14 inches in size, or the size of a large squash.

Weeks 28-32

  • What to expect: Early in the third trimester, visits to the doctor may seem relatively uneventful, but are still very important. You may begin to notice some additional symptoms of pregnancy, such as difficulty sleeping, lower back and leg pain, pelvic pressure, and braxton hicks contractions, also known as false labor. These contractions aren't consistent. Drink water and rest, and if it's not real labor, they'll will go away).
  • What you can do: Rest, and get comfortable (with lots of pillows!) while doing so. Pregnancy support belts (or a “belly band”, an elastic band that helps to lift the belly), kinesiology tape, swimming (hello, no gravity!), and massage can all help alleviate typical aches and pains. You know what else helps? You guessed it, drinking water. Water is especially good for braxton hicks contractions, as they can often be caused by dehydration. Additionally, the Tdap (or whooping cough) vaccine is recommended once in the third trimester. A flu shot can be administered at any point during pregnancy and is highly recommended!
  • Baby’s growth: Baby is about 16 inches in size and weighs around 4lbs, about the size of a large cabbage.

Weeks 32-35

  • What to expect: Additional lab work may be done, depending on your provider.
  • What you can do: Make sure you’ve got the things you’ll need at home, like a breast pump and a car seat. Breast pumps are often times covered by insurance with a written prescription, so bring this up to your provider.
  • Baby’s growth: Baby is about 17-18 inches, or close to the size of a pineapple.

Weeks 36-delivery

  • What to expect: You're in the home stretch! A group B strep swab will be collected, which is a rectal-vaginal swab used to check for the presence of group B strep, a bacterial strain, in the vagina. Some women have it, some don't. It doesn't mean one thing or another about you-- but if you test positive, antibiotics will be administered in labor to prevent transmission to baby.
  • What you can do: Rest and enjoy one-on-one time with your partner or solo time for yourself.
  • Baby’s growth: Baby starts this phase at about 17-19 inches, which is similar in size to a watermelon!

While this guide should certainly help quell some fears and uncertainties, your provider is your best source of info throughout pregnancy. Write any questions down as they come to mind, so you'll have them on hand at visits. Pregnancy is different for everyone, and information is your best ally!


Kara Earthman

Kara Earthman is a Women's Health Nurse Practitioner (WHNP) and writer living and working in Nashville, TN. You can find more of Kara's work on her blog EarthWoman.

Fertility Unfiltered