Prenatal Tests Timeline: Every Scan and Test by Trimester

Prenatal care is one of the most effective things you can do for a healthy pregnancy. Each appointment, scan and test has a job: confirming your dates, spotting problems early while there is still time to act, and planning a safe birth.

This is the timeline the Prego app follows in its to-do list. Exact timings vary by country and by your own health, so always follow your provider's plan.

How often are prenatal appointments?

Weeks	Typical schedule
First visit	Around 8 to 10 weeks
Up to 28 weeks	Every 4 weeks
28 to 36 weeks	Every 2 weeks
36 weeks to birth	Every week

At almost every visit your provider checks your blood pressure, your weight, your urine for protein and infection, and, from about 20 weeks, your fundal height (the size of your uterus). These quick checks are how preeclampsia, a dangerous rise in blood pressure, is caught early.

First trimester (weeks 1 to 13)

Your first prenatal visit

Early registration with an OB-GYN or midwife sets up your care plan and identifies any risk factors from the start. Bring a list of medicines, any health conditions and the date of your last period.

First trimester blood tests

Complete blood count: checks for anemia, infection and platelet problems.
Blood type and Rh factor: if you are Rh negative, you may need an injection later to protect your baby.
Infection screening: HIV, hepatitis B, syphilis and sometimes hepatitis C, which can all pass to your baby but can be treated or managed.
Rubella immunity: to check you are protected.
Blood sugar (glucose or HbA1c): finds diabetes that was there before pregnancy.
Thyroid function: untreated thyroid problems can affect your baby's brain development.

Urine test

Looks for protein and for bacteria that cause no symptoms but can spread to the kidneys in pregnancy.

Dating ultrasound

Confirms your due date, how many babies you are carrying and that the pregnancy is in the uterus. It is the most accurate way to date a pregnancy. You can compare it with our due date calculator.

Genetic screening (optional)

NIPT (cell-free DNA), from 10 weeks: a blood test that screens for Down syndrome, trisomy 18 and trisomy 13 with high accuracy and no risk to your baby.
Combined screening, at 11 to 13 weeks 6 days: a nuchal translucency ultrasound plus blood tests (PAPP-A and hCG).

Screening tests estimate risk; they do not diagnose. If a result is high risk, your provider will discuss diagnostic tests like CVS or amniocentesis.

Other early checks

A dental check-up is worth booking, since pregnancy hormones increase the risk of gum disease. A cervical screening (Pap) test may be done if you are due one. It is also a good time to talk about your mental health: hormonal changes can trigger anxiety or depression, and support works best early.

Second trimester (weeks 14 to 27)

Quad screen (15 to 22 weeks)

If you didn't have NIPT, this blood test screens for Down syndrome, trisomy 18 and open neural tube defects like spina bifida.

Anatomy scan (18 to 22 weeks)

A detailed ultrasound that checks your baby's brain, heart, spine, limbs and organs, as well as the placenta and amniotic fluid. You can usually find out the sex here if you want to. See what's happening at 20 weeks.

Glucose screening (24 to 28 weeks)

Gestational diabetes usually develops mid-pregnancy and often has no symptoms, so this test is the only way to find it. You drink a sugary drink and have your blood sugar checked an hour later. If it is high, you will have a longer test.

Iron check

Iron levels often drop as your blood volume expands. Anemia can cause tiredness and increases the risk of preterm birth, so your provider may recheck your blood count around 24 to 28 weeks.

Third trimester (weeks 28 to 40+)

Rh immunoglobulin (28 weeks)

If you are Rh negative, an anti-D injection at around 28 weeks stops your body from making antibodies that could harm an Rh-positive baby in this or a future pregnancy.

Tdap vaccine (27 to 36 weeks)

The whooping cough vaccine passes antibodies to your baby through the placenta, protecting them before they are old enough for their own shots. Your provider may also recommend the flu vaccine (any trimester) and, depending on the season and where you live, the RSV vaccine (32 to 36 weeks).

Kick counting (from 28 weeks)

Getting to know your baby's movement pattern is one of the simplest ways to monitor their wellbeing. Try our free kick counter, and contact your provider straight away if movements slow down or change.

Group B strep swab (36 to 37 weeks)

A quick vaginal and rectal swab for GBS bacteria, which are harmless to you but can cause serious infection in a newborn. If it is positive, you will get antibiotics during labor.

Growth scans and non-stress tests

Some people have extra ultrasounds to check the baby's size, position and fluid, or a non-stress test, which monitors your baby's heart rate as they move. These are more common if you have a health condition or go past your due date.

Birth planning

Talk to your provider about your birth plan, pain relief options and when to come in. Pre-registering at your hospital saves time when labor starts.

Frequently asked questions

Are prenatal genetic screening tests required?

No. Screening for chromosomal conditions is offered to everyone but is your choice. Your provider can help you decide what is right for you.

Is ultrasound safe in pregnancy?

Yes. Ultrasound uses sound waves, not radiation, and has been used safely in pregnancy for decades when done for medical reasons.

What happens if I miss an appointment?

Call your provider to rebook as soon as you can. Some tests, like the combined screening or the glucose test, have time windows, so it is worth rescheduling quickly.

Sources

General information only, not medical advice. Always follow the guidance of your doctor or midwife.

History of updates

October 21, 2026: Published.