Every pregnancy is different, but every pregnant person wants to know: what's happening in there right now? Here's a trimester-by-trimester look at what's going on with your baby, your body, and what you can actually do about all of it.
First trimester (weeks 1-12)
What's happening with baby
The first trimester is where the heavy lifting happens. By week 5, the heart starts beating. By week 8, all major organs have started forming. By week 12, your baby is about the size of a lime, has fingers and toes, and can make tiny fist movements. The neural tube (which becomes the brain and spinal cord) closes by week 6 — this is why prenatal folate is so critical early on.
What's happening with you
Nausea, exhaustion, breast tenderness, and emotional roller coasters — thank the rapid rise in hCG and progesterone. Morning sickness (which strikes at any time of day) peaks around weeks 8-10 for most people and usually improves by week 14. The fatigue can be staggering. Your body is building an entire organ (the placenta) while simultaneously growing a human. It's okay to nap at lunch and go to bed at 7:30.
Key appointments: First prenatal visit around weeks 8-10. Dating ultrasound to confirm due date. First trimester screening (blood work + nuchal translucency ultrasound) between weeks 11-13 if you choose genetic screening.
Second trimester (weeks 13-26)
What's happening with baby
The "golden trimester" for good reason. By week 16, baby can hear your voice. By week 18-22, you'll likely feel those first flutters of movement (called "quickening" — earlier if it's not your first baby). By week 20, the anatomy scan can check all major organs and often reveal biological sex. By week 26, baby is about the length of a zucchini, practicing breathing movements, and developing sleep-wake cycles.
What's happening with you
Energy returns. Nausea usually fades. Your bump becomes visible, which makes it feel more real. But new symptoms arrive: round ligament pain (sharp twinges on the sides of your belly), nasal congestion (thanks, increased blood volume), and possibly heartburn as your growing uterus pushes your stomach upward.
This is a good time to start or maintain gentle exercise — walking, swimming, and prenatal yoga are excellent options. It's also when many people begin nursery planning, registry building, and prenatal classes.
Key appointments: Anatomy scan at 18-22 weeks. Glucose screening for gestational diabetes around weeks 24-28. Regular prenatal visits every 4 weeks.
Third trimester (weeks 27-40+)
What's happening with baby
Baby is gaining weight rapidly — about half a pound per week. The lungs are maturing, getting ready to breathe air. Brain development explodes during this trimester. By week 37, baby is considered "early term." By week 39, they're "full term" and ready for the outside world. Most babies settle into a head-down position by weeks 32-36.
What's happening with you
Everything is more. More tired. More uncomfortable. More bathroom trips (baby's head is pressing on your bladder). Braxton Hicks contractions become more noticeable — they're practice contractions, irregular and not painful. Trouble sleeping is extremely common due to discomfort, anxiety, and the need to pee every 90 minutes.
Swelling in your feet and ankles is normal, but sudden swelling in your face or hands, especially with headaches or vision changes, needs immediate medical attention as it could signal preeclampsia.
Key appointments: Visits increase to every 2 weeks, then weekly after week 36. Group B strep test around week 36. Discussions about birth preferences and labor signs.
When to call your provider
Throughout pregnancy, contact your healthcare provider for: bleeding (any amount, any trimester), severe abdominal pain, sudden swelling of face or hands, severe headache that doesn't resolve, vision changes, fever over 100.4°F, decreased fetal movement after week 28 (fewer than 10 movements in 2 hours during a kick count), and fluid leaking from your vagina (could be amniotic fluid).
When in doubt, call. Your provider's office handles these calls constantly. You are never bothering them.
The big picture
Pregnancy lasts about 40 weeks, but babies arrive on their due date only about 5% of the time. Anywhere from 37-42 weeks is within the normal range. Your body is doing something extraordinary, and no two pregnancies — even for the same person — follow exactly the same script. Trust the process, show up to your appointments, and don't be afraid to advocate for yourself when something doesn't feel right.
Related: Morning Sickness Remedies | Pregnancy Nutrition Guide | Birth Plan Guide