Why Are Ultrasounds Performed?

Ultrasound imaging is a safe, non‑invasive diagnostic tool used throughout pregnancy to monitor both maternal and fetal health. Here’s a trimester‑by‑trimester breakdown of medically indicated ultrasound exams and what parents can expect at each stage.

First Trimester (0–13 Weeks)

• Confirm pregnancy: Visualize the gestational sac and embryo.
• Heartbeat detection: Verify fetal cardiac activity and measure heart rate.
• Crown–rump length: Determine accurate gestational age.
• Due‑date estimation: Calculate estimated date of delivery (EDD).
• Molar & ectopic screening: Rule out abnormal implantations.
• Assess abnormal gestation: Identify bleeding, blighted ovum, or miscarriage risk.

Second Trimester (14–27 Weeks)

This period is critical for detailed anatomy scans and growth assessments:

• Fetal anatomy scan (18–22 weeks): Detect congenital malformations and structural abnormalities.
• Early genetic markers (13–14 weeks): Assess nuchal translucency and other Down‑syndrome indicators.
• Growth & dating: Verify fetal size, amniotic fluid levels (hydramnios/oligohydramnios), and confirm or adjust EDD.
• Multiples confirmation: Identify twins or higher‑order pregnancies.

Baby’s Development Milestones

Weeks 14–16

• Transparent skin & lanugo formation
• Fingerprints develop; swallowing begins
• Baby measures ~4″ CRL, weighs 3–4 oz (size of an avocado)

Weeks 17–20

• Eyebrows, eyelashes & nails appear
• Movements felt; heartbeat audible via stethoscope
• Length ~6″ CRL (10″ head‑to‑toe), weight ~10 oz

Weeks 21–24

• Skin less transparent; baby looks more proportional
• Uterus size ~soccer ball; kicks replace flutters
• Weight ~1 lb 5 oz; length ~12″

Weeks 24–27

• Sleep‑wake cycles form; baby hiccups
• Skin smooths as fat accumulates; eyes open by week 27
• Weight ~2 lb; length ~14 – 15″

Third Trimester (28–40 Weeks)

• Placenta location: Rule out previa or abruption.
• Fetal presentation: Determine head‑down vs. breech.
• Growth monitoring: Track weight, fluid levels, and biophysical profile.
• Maternal anatomy: Check uterine and pelvic health.

4D Ultrasound: What to Expect at Each Stage

• 8–14 weeks: Early whole‑baby views & heartbeat listening.
• 15–18 weeks: Full‑body 3D captures & gender determination.
• 26–30 weeks: Well‑defined facial features emerge.
• 31–36 weeks: Chubby cheeks & detailed expressions for classic keepsake images.

By understanding the purpose and timing of each ultrasound exam, both providers and parents can maximize diagnostic value and create unforgettable keepsakes. Contact us to schedule your 3D/4D session today.