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Easy Definitions for Pregnancy Health Tests Part 1

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Pregnancy is a magical time. And one that demands attention. So if you’re high risk or your normal prenatal tests have suspicious results, your care provider may begin talking about medical tests with scary, unfamiliar names.

Therefore, to help you understand them, let’s break down some pregnancy medical test definitions.

First of all, there are two general categories of pregnancy tests

  • invasive 

  • non-invasive

Invasive tests require going into your body to gather biological samples. And they are usually done with a needle inserted into your cervix, vagina, or abdomen.

Follow the links below to read more deeply about invasive tests. Another post (Part 2) will cover Non-invasive tests.



An extra chromosome is called ‘trisomy’. And trisomies can cause intellectual difficulties or physical malformations.

CHORIONIC VILLIUS SAMPLING (CVS) (“core-ee-on-ic vil-us” sampling)

An invasive test in which a small part of the placenta is removed. It tests for chromosomal/genetic conditions like

  • trisomies (which include Down syndrome)
  • Tay-Sachs disease
  • cystic fibrosis

But it cannot test for spina bifida.

CVS is usually done before amniocentesis.  And between weeks 10-12 of pregnancy. The two ways it’s done are

  1. Transcervical (through the vagina)
  2. Transabdominal (through the abdominal wall).

Risks include

  • miscarriage
  • rhesus (Rh) sensitization
  • and infection

AMNIOCENTESIS (“am-knee-oh-sen-tee-sis”)

An invasive procedure. A small amount of amniotic fluid is drawn out via a needle inserted through the abdomen into the uterus.

There are two main kinds of amnio

  1. Genetic — tests for chromonsonal conditions: Down syndrome and spina bifida. Usually done between weeks 15 and 18.
  2. Maturity  tests  baby’s lungs are developed enough to function after birth. Usually done prior to elective delivery, between weeks 36-39 of pregnancy.

Small degree of risk includes

  • possible miscarriage
  • leaking amniotic fluid
  • injury to baby or mom
  • introducing infection or transferring it from mom to baby
  • preterm labor.

CORDOCENTESIS (“cord-o-cen-tee–sis”)

Invasive procedure used if amniocentesis, CVS, and ultrasound haven’t given clear results.

A needle is inserted through the abdomen and uterus. It rests where baby’s umbilical cord meets the placenta. A small sample of baby’s cord blood is removed to detect

  • blood conditions and infections,
  • fetal malformations, fetal anemia, and
  • isoimmunisation

Cordocentesis is usually done after the 17th week of pregnancy.

Risks include

  • miscarriage
  • bleeding
  • slowing baby’s heart rate
  • and uterine infection

A basic understanding of the tests and how to pronounce them empowers you to ask informed questions.

The more you understand, the better the final version of your birth plan and the more complete your hospital bag checklist will be.

The better your questions, the more your care provider can work with you. And the more you can work with your care provider, the safer you and your baby will be!


To learn more about healthy pregnancy, download our free Birth Plan eBook now. After three years of research, collaboration with more than 100 childbirth experts and resource centers from Healthy Child Healthy World to the American Association of Neonatal Nurses, the Best Ever Baby Birth Plan Guide is available for a free download.

This new resource for pregnant families is a compilation of top tips and advice from more than 20 nationally-recognized experts in the field including renowned pediatrician, Dr. Alan Greene and GraceFull Birthing founder, midwife Elizabeth Bachner. These trusted experts offer thoughtful guidance for whatever type of birthing experience parents want, in whichever setting they choose.

Published: October 10, 2015 | Reviewed by: Kim Walls, Natural Products Expert, Elizabeth Bachner, LM, CPM, L.Ac., Midwife | Last reviewed: October, 2015

Kim WallsEasy Definitions for Pregnancy Health Tests Part 1

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