The Hello Baby Pregnancy Timeline

Weeks 4–8: early pregnancy

A positive test, a rising hCG level, and a pregnancy that is still measured in millimetres. The gestational sac appears around week 5, a yolk sac shortly after, and a fetal pole with cardiac activity around week 6 to 6.5. By week 8 there is a recognisable little shape with limb buds, and often the first twitchy movements.

• Ultrasound can show: location of the pregnancy, number of babies, cardiac activity, and accurate dating.
• Ultrasound cannot show: sex, facial features, or anything 3D.
• Usually transvaginal at this stage — it gets far closer and produces much better detail.
• Early DNA sex determination is possible from about 6 weeks — that is a blood test, not imaging.

Weeks 8–14: first trimester milestones

Enormous change in a short window. Fingers and toes separate, the head becomes proportionally less dominant, and your baby starts moving in a way that looks purposeful. Most first prenatal visits and dating scans land here, along with first-trimester screening options around 11 to 13 weeks.

• Best window for accurate dating — the due date set here is the one that generally sticks.
• Scanning shifts from transvaginal to abdominal for most people around weeks 10 to 12.
• Nausea often peaks and then begins to ease toward the end of this stretch.

Weeks 14–20: gender and anatomy stage

The stage most families are impatient for. Sex can usually be determined by ultrasound from about 15 weeks, with confidence improving each week after. The detailed anatomy scan is typically done between 18 and 22 weeks — that is a diagnostic study ordered by your provider, and it is an important one.

• Ultrasound can show: sex, full anatomy survey, placenta location, fluid levels.
• 3D at this stage gives sweet full-body images, but faces still look thin — babies have not put on fat yet.
• You may start feeling movement around 16 to 22 weeks — later if you have an anterior placenta.

Weeks 20–33: growing features and movement

Your baby fills out. Fat begins to accumulate under the skin, features soften and round, and movement becomes strong enough for other people to feel. Glucose screening usually happens around 24 to 28 weeks. From about 26 weeks — when baby is around 2 pounds — we can start getting a genuinely good 3D face, just with leaner cheeks than later on. Twins reach their best window here, roughly 26 to 30 weeks, before two babies run out of room.

• 3D images improve week over week through this stretch.
• The earliest lovely single-baby faces; the sweet spot for twins.
• Good time to book hospital tours and childbirth classes.

Weeks 34–36: the 3D/4D sweet spot ⭐

For a single baby, this is our favourite window. Your baby is around 5 to 6 pounds, so the cheeks are full and the face looks like the baby you are about to meet. Most babies have settled head-down into a predictable position, and the placenta has usually travelled higher as the uterus grew, clearing the view it may have blocked earlier. If you are only doing one 3D/4D session, this is when to come.

• Best odds of the portrait most families are picturing.
• Position is the main variable now — see why your baby's face may be hard to see.
• Pack your hospital bag by about 36 weeks, so this is a good time to start.

Weeks 37+: still a beautiful time to come

Unlike a lot of studios, we are happy to scan you right up to your due date — the face only gets fuller and chubbier. The main variable this late is simply your baby's position on the day, so a little patience helps. If a session earlier in pregnancy did not get the face, a later visit is often exactly what does.

• Full, rounded features — many families' favourite images come from these late sessions.
• Weekly provider visits usually begin around 36 weeks.
• Any decrease in movement: call your provider the same day, every time.

Appointment planning checklist

• Confirm your gestational age with your provider, not an app
• Ask whether you have an anterior placenta — it affects timing
• Decide whether you want one session or two (early sex reveal + later portrait)
• Check deployment, travel, and PCS dates before choosing a week
• Book the 3D/4D session for 34–36 weeks (26–30 for twins); earliest good face is about 26 weeks
• Invite your guests — the lounge seats 10+
• Tell us in advance if you are planning a sealed gender reveal
• Schedule your hospital tour for 24–30 weeks
• Pack your hospital bag by 36 weeks
• Have the car seat installed and checked by 36 weeks