Prenatal Testing: Understanding Your Options

- Sep 22nd, 2025

During pregnancy, you’ll hear about different kinds of prenatal tests. These tests are tools that can give you information about your baby’s growth and development. Some people find this information reassuring, while others may choose not to have testing at all. Both choices are valid.

This handout is meant to help you understand the different types of prenatal testing available, so you feel confident making the decision that’s right for you.

Why Prenatal Testing is Offered

Prenatal testing can:

• Estimate the chance your baby may have certain conditions.
• Give a clear diagnosis in some cases.
• Offer information that may help you prepare for birth and beyond.

It’s important to know that all prenatal testing is optional. You can choose the amount of information that feels right for you and your family.

Non-Invasive Screening Options

These tests use blood work and ultrasounds. They carry no risk to your baby and can give you an estimate of the likelihood of certain genetic conditions. They do not give a definite “yes” or “no” answer.

Non-Invasive Prenatal Testing (NIPT or NIPS)

(In my practice I use a company called Unity - unityscreen.com has a lot more information if you want to learn more about this test)

What it is: A simple blood test that looks at small pieces of your baby’s DNA circulating in your bloodstream. Cell-free DNA (cfDNA) can be found circulating in the maternal blood stream as early as 5 weeks. To be able to achieve an adequate fetal fraction, it is recommended to wait until 10+ weeks to have this test done.

When it’s done: Anytime after 10 weeks of pregnancy.

What it tells you: The chance of conditions like Down syndrome (trisomy 21), trisomy 18, trisomy 13, and differences in the sex chromosomes. Some labs can also assess if a baby's blood type is Rh positive or negative, which can be useful information when the maternal blood type is Rh negative.

Things to know: NIPT is one of the most accurate screening tools available, but it’s still a screening. If results suggest a higher chance of a condition, your provider may offer diagnostic testing for confirmation. False positive rates are as low as 1-2 per 1000 live births.

It can also be paired with a genetic carrier screen for the parents. This gives information regarding any conditions that the parent may have that can be passed down to the baby and the probability of that occurring.

Sequential or Integrated Screening

What it is: Two blood tests (one in the first trimester, one in the second) combined with an ultrasound that measures the baby’s neck (nuchal translucency).

When it’s done:

• First part: 11–14 weeks
• Second part: 15–20 weeks

What it tells you: Risk assessment for chromosomal conditions, similar to NIPT. This check for certain markers in the maternal circulation: PAPP-A and HCG.

Things to know: Results are less accurate than NIPT and take longer since you wait for both sets of tests.

Quad Screen

What it is: Blood test

When it’s done: Second trimester

What it tells you: Risk assessment for chromosomal conditions and neural tube defects (NTD). This one includes 4 markers that are looked at, and they are: Estriol, AFP (Alpha-fetoprotein), HCG, and Inhibin-A.

Marker	Source	Normal Role	Abnormal Levels May Suggest
hCG (Human Chorionic Gonadotropin)	Placenta (trophoblasts)	Maintains corpus luteum → progesterone support in early pregnancy	↑ High: Down syndrome, multiple gestation ↓ Low: Miscarriage risk, ectopic pregnancy, trisomy 18
Alpha-fetoprotein (AFP)	Fetal liver, yolk sac	Major fetal plasma protein	↑ High: Neural tube defects (spina bifida, anencephaly), abdominal wall defects, multiple gestation ↓ Low: Down syndrome, trisomy 18
Inhibin-A	Placenta, ovaries	Regulates FSH production	↑ High: Down syndrome risk ↓ Low: Trisomy 18 risk
PAPP-A (Pregnancy-Associated Plasma Protein-A)	Placenta	Promotes healthy placental and fetal development	↓ Low: Down syndrome, trisomy 18, adverse outcomes (growth restriction, preeclampsia, miscarriage)
Estriol (uE3, unconjugated estriol)	Placenta (from fetal adrenal + liver precursors)	Estrogen supporting uteroplacental blood flow	↓ Low: Down syndrome, trisomy 18, anencephaly, placental insufficiency

Diagnostic (Invasive) Testing

Diagnostic tests can give you a definite answer, but they are invasive and carry a small risk of miscarriage. They are usually offered if a screening test suggests a higher chance of a condition, or if someone wants the most certain information possible.

Chorionic Villus Sampling (CVS)

(This test is usually performed by an MFM - Maternal Fetal Medicine physician)

When it’s done: 10–13 weeks

How it works: A small sample of the placenta is collected, either transvaginally or transabdominally.

What it tells you: Can diagnose chromosomal differences and some genetic conditions.

Things to know: Provides results earlier in pregnancy, but carries a small risk of miscarriage.

Amniocentesis

When it’s done: 15–20 weeks

How it works: A thin needle takes a small sample of amniotic fluid surrounding the baby.

What it tells you: Chromosomal conditions, genetic differences, and neural tube defects.

Things to know: Very accurate, but results come later in pregnancy than CVS. Very small risk of miscarriage, depending on the experience of the provider performing the test. Other risks to consider (but not all) are maternal-fetal bleed, infection, and rupture of membranes.

Other Tests

Carrier Screening
Looks at your own genes (and possibly your partner’s) to see if you carry certain inherited conditions like cystic fibrosis, sickle cell disease, or spinal muscular atrophy.
Best done before pregnancy or early in the first trimester.
Helps you understand if your baby could be at risk for certain inherited conditions.

Ultrasounds
First trimester: Confirms pregnancy, estimates due date, may include the nuchal translucency measurement.
Anatomy scan (18–22 weeks): A detailed look at your baby’s organs, growth, and development, placenta location.
Additional ultrasounds may be suggested if there are questions about growth or health later in pregnancy.

Questions You Might Ask Your Care Provider

• What information will this test give me?
• How accurate is it?
• Are there any risks to me or my baby?
• What happens if the result shows a higher chance of a condition?
• If I choose not to test, what will we know from ultrasounds and other routine care?

Remember: Prenatal testing is about giving you options and information. You are the one who gets to decide what feels right for you and your family. Some people want as much information as possible, while others prefer not to test unless there’s a medical reason. There is no “right” or “wrong” choice—just the one that fits best for you.