The Third Trimester Checklist: What Actually Matters in the Last 12 Weeks

The third trimester is the point in pregnancy when the internet gets loudest. Every list is longer than the last one and half the items feel invented — buy this pillow, journal this feeling, try this tea. Meanwhile the actual, non-negotiable list is short, and most of it is scheduled by your doctor.

This is that list: the tests, the vaccines, the daily habit, the decisions, and the setup that matter between 28 weeks and delivery — with every claim tied to an actual medical source, and everything else left out. If you are earlier in pregnancy and want the whole arc, our pregnancy checklist covers all three trimesters.

01First: where you are

According to the Cleveland Clinic, "the third trimester of pregnancy begins at 28 weeks and ends at 40 weeks (or until you give birth)." It is roughly the last three months, and it is when your prenatal appointments start stacking closer together.

The same guide describes the standard cadence: "appointments occur every two weeks up until the 36th week of pregnancy. For the last four weeks of pregnancy, you go weekly." So if you are 28 weeks, you have somewhere around eight to twelve appointments between now and meeting your baby — which is exactly the point. This is when things can change quickly, and the schedule is designed to catch problems early.

02The medical to-dos with actual due dates

There are really only three third-trimester items with clear timing you can put on a calendar. Everything else is a soft recommendation. These three are not.

Tdap between 27 and 36 weeks

Tdap is the vaccine that protects your baby from whooping cough — pertussis — in the weeks after birth, before they are old enough for their own shot. The Cleveland Clinic puts it plainly: "health authorities recommend the Tdap vaccine starting in the 27th week of pregnancy," and "babies can't get their first dose of the Tdap vaccine until their two-month visit," which "leaves a critical window of time where they can be infected with whooping cough during their first weeks of life." Getting Tdap in this window is how you close that window.

The Cleveland Clinic also notes you should "get a Tdap vaccine during every pregnancy, regardless of whether you've had one in the past" — your antibody levels fade over time, so a shot from a previous pregnancy is not enough.

RSV vaccine between 32 and 36 weeks (in season)

RSV is the other big respiratory infection that hits newborns hard. The Cleveland Clinic writes that the RSV vaccine "is administered during the third trimester (between 32 and 36 weeks of pregnancy) during the RSV season." It is seasonal because it is timed to when RSV is actually circulating; your OB will tell you whether it applies to your due date.

Group B strep swab around 36 to 37 weeks

Group B strep (GBS) is a common bacteria that lives harmlessly in about "1 in 4 females" during pregnancy, per the Cleveland Clinic. The reason it matters is that it can be passed to the baby during a vaginal birth — but that risk is almost entirely preventable if you know.

So near the end, "your healthcare provider will test you for GBS around 36 to 37 weeks of pregnancy." It is a simple cotton swab — "Your obstetrician uses a cotton swab to obtain samples of cells from your vagina and rectum." If it comes back positive, you get IV antibiotics during labor: "The most common antibiotic to treat group B strep is penicillin or ampicillin," and they "work best when given at least four hours before delivery." The numbers back up how much this matters — "With antibiotic treatment, about 1 in 4,000 babies will get a GBS infection at birth," versus "about 1 in 200" without.

03The one daily habit: pay attention to movement

There is one thing to do every single day of the third trimester, and it is free. The Cleveland Clinic explains that "kick counting becomes more important in the third trimester, when changes in movement can sometimes signal a problem." The nonprofit Count the Kicks recommends you "begin counting in the third trimester, which is at 28 weeks, or 26 weeks if you are high-risk or pregnant with multiples."

You do not need an app, though there is one. You need a quiet minute, once a day, at roughly the same time. The Cleveland Clinic gives two equally valid methods: "Count the number of kicks you feel in one hour" or "Measure the amount of time it takes to feel 10 kicks."

04The decisions to make (not the ones the internet argues about)

The AAP's HealthyChildren.org frames the third trimester decision list gently: "As pregnancy progresses, you're confronted with a long list of related decisions, from planning for the delivery to decorating the nursery to choosing a pediatrician." The ones actually worth putting on your list, per the AAP, are these:

• Choose a pediatrician. The AAP lists "Finding a Pediatrician" as a core prenatal decision. Many pediatric practices do "prenatal interview" visits — 15 to 20 minutes to meet the doctor before you deliver. Do at least one.
• Decide how you plan to feed. The AAP frames this as a decision to think through in advance: "Should I Breastfeed or Bottlefeed?" You can absolutely change your plan, and many parents do — but knowing your preference now means you can line up support (a lactation consultant, formula on hand, both) instead of scrambling in week one.
• If you're having a boy, decide about circumcision. The AAP treats this as a parental choice with an assist: "Circumcision: A Parent's Choice." Your pediatrician can walk you through it before delivery.
• Decide about cord blood. The AAP has published policy guidance on "Newborn Umbilical Cord Blood Banking and Donation" so families can decide with real information rather than sales pitches.
• Pick the sleep space — bassinet or crib — and the going-home car seat. Both need to be actually installed and set up before delivery, not the day of.

05Set up the space your baby will actually sleep in

The nursery Pinterest board is fun. The safe sleep setup is the thing. The AAP's safe sleep guide lays out the non-negotiables — and these are the ones to actually get right before you come home.

For the wider list of gear that actually earns its space, our guide to nesting during pregnancy walks through what to set up in each room without buying two of everything.

06Common symptoms — the ones that are normal

A lot of what happens in the third trimester feels alarming and is not. The Cleveland Clinic's list, straight from the source:

• Braxton Hicks contractions. Per the Cleveland Clinic: "Braxton Hicks contractions are mild, irregular and don't progress. They can feel more like menstrual cramps."
• Shortness of breath. "It can be difficult to take deep breaths in the third trimester. This is mainly because your lungs don't have as much room to expand."
• Peeing all the time. "When the fetus moves further into your pelvis, it can press on your bladder. This can lead to symptoms like peeing more often."
• Heartburn and indigestion. "Your growing uterus can press on your stomach and send stomach acids upward, causing symptoms like heartburn and indigestion."

07Warning signs — call today, not tomorrow

The Cleveland Clinic lists these as reasons to call your provider in the third trimester:

• A decrease in fetal movement. "How often the fetus moves can vary, but if you go longer than usual without feeling any movement, contact your provider."
• Signs of preterm labor — regular contractions or pressure before 37 weeks.
• Vaginal bleeding.
• Severe abdominal cramps.
• Dizziness and severe headaches.

Preeclampsia is the reason those last two matter so much. The Cleveland Clinic says to go to the hospital immediately if you have a "severe headache that won't go away," "blurry vision," "dark spots in your vision that don't go away," "shortness of breath," or "sharp pain in your abdomen (specifically the right side)." Swelling in your hands and face can also be part of the picture. If any of that lines up, do not wait until Monday.

08Pack the bag by 36 weeks

Most people go into labor sometime in a two-to-three-week window around their due date, and a small share go earlier. The safe move is to have your hospital bag packed and by the door around 36 weeks — not the night contractions start. Our hospital bag list covers exactly what to put in it (for you, your partner, and the baby) without any of the padding.

The other thing to do around then: install the infant car seat and, if possible, have it checked. Most hospitals will not discharge you without one, and many fire stations, police stations, and certified passenger safety technicians will inspect an installation for free — do a search for "car seat check" in your city plus "CPST."

09One last thing: line up your first two weeks

The third trimester is also when it is easiest to plan the first two weeks after delivery — because you still have energy and time to make phone calls. That means: who is coming when, who is not, meals lined up in the freezer, the pediatrician's first appointment on the calendar, and — if you want it — any overnight help booked. Our newborn basics guide covers the fundamentals for those first weeks, and there is no bad time to read it now instead of at 2 a.m. later.

That is the whole checklist. Three tests and vaccines with real due dates. One daily habit. A short list of decisions the AAP actually cares about. A safe sleep setup, an installed car seat, and a packed bag. Everything else is a nice-to-have.

Questions parents actually ask

Newborn Weeks is planning help, not medical advice — always follow your own doctor, midwife, or pediatrician.