Prenatal lab tests: what to order and when

Why a test timeline matters

Brazilian prenatal care spreads labs and imaging across about forty weeks¹, not a single blood draw day. Seeing that arc helps you ask better questions, book the anatomy scan before week 24, and place glucose screening between weeks 24 and 28².

Levvi aligns reminders with gestational age — it organizes information; your clinician still interprets results and sets treatment.

Overview by trimester

This table summarizes typical timing in low-risk pathways¹². Access may vary by city or insurance, but the windows stay similar.

First visit — initial panel (by week 12)

The first appointment confirms pregnancy, dates gestational age, and screens conditions affecting mother and baby¹². Earlier is better so supplementation and treatable diagnoses are not delayed.

Bring ID, health card, medication list, and surgery history. If you already have a positive home test, share that date.

Tests commonly ordered at the start

• CBC — anemia, platelets

• Blood type and Rh — indirect Coombs if Rh negative

• Fasting glucose

• Serologies: HIV, syphilis, toxoplasmosis, hepatitis B

• Urinalysis and culture

• Hemoglobinopathy screening when indicated

• Cervical cytology if overdue

• Early ultrasound weeks 11–14 when available

Second trimester — anatomy, metabolism, movements

Weeks 18–24 bring the anatomy scan²³. Limited access? Prioritize uncertain dating or higher-risk situations².

The 75 g OGTT (weeks 24–28) screens for gestational diabetes². Confirm fasting rules and bring a post-test snack.

Many people feel movement around weeks 18–22 — mention at visits if you feel nothing yet, without immediate panic⁴.

Third trimester — repeats and vigilance

HIV may repeat around weeks 28–30 if the first test was non-reactive¹. Toxoplasmosis may repeat if you were susceptible at the start².

Repeat CBC after week 30 monitors anemia⁴. GBS screening weeks 35–37 plans intrapartum antibiotics if positive⁵.

Visits become every two weeks after week 28 and weekly from 36 to 41¹.

Organizing results calmly

Keep PDFs named by date. At visits, open chronological results so your team saves time and you avoid duplicate draws.

If a public clinic cannot offer a test, ask referral or priority: dating, anatomy scan, OGTT, and HIV are often most urgent².

When to call before the next visit

Heavy bleeding, severe pain, high fever, major fluid leak, or clearly reduced fetal movement (after a known pattern) warrant same-day contact¹.

How Levvi can help

My Pregnancy surfaces week-based tasks with links here. Tasks let you mark completion; Medications logs supplements alongside daily symptom notes.

Frequently asked questions

Do I need every test at once? No — early labs cluster; later tests have specific windows².

Can the app diagnose? No — it educates and organizes; clinicians interpret and treat.

Does a normal ultrasound rule out everything? No — it screens; full prenatal care combines labs, visits, and your symptom reports.

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