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Prenatal Screening

Your baby’s development begins while they’re still microscopic.

Screening for Chromosomal Abnormalities

Your baby’s development begins while they’re still microscopic. There’s a lot going on at the cellular level that sets the course for how your child will develop. This is the level where chromosomal abnormalities can happen, and this can lead to health problems.

How do chromosomal abnormalities happen, and is it possible to screen for or prevent them during your pregnancy? Valley Perinatal Services has answers.

When Chromosomal Abnormalities Happen

Chromosomes are thread-like structures found in the nucleus of every single cell in the body. Humans have 23 pairs of them, with 46 chromosomes total. These chromosomes contain the genetic information that tells the body’s different types of cells how to do their jobs. Errors in chromosomes can happen during cell division, and some genetic or environmental factors may also be linked to chromosomal abnormalities in pregnancy.


When sex cells divide, they create cells with half the number of chromosomes, which allows each parent to give 23 chromosomes to their child so they end up with the total of 46. If this process doesn’t happen correctly, a child could have an extra chromosome (trisomy) or be missing a chromosome (monosomy). This can cause a variety of disorders including Down’s syndrome, Patau’s syndrome, or Edward’s syndrome. Problems in meiosis could also lead to miscarriage or stillbirth.


Once the baby begins to grow, the cells undergo mitosis. This is when a cell duplicates by doubling its chromosomes, then splitting in half to get back down to the correct number. This process repeats as the baby grows and continues throughout their life to replace cells that are damaged or dead. Errors in this process can also lead to extra or missing chromosomes.

Prenatal Screening for Chromosomal Abnormalities

Tests to screen for chromosomal abnormalities in pregnancy can be performed as early as 11 weeks into pregnancy. Screening tests are not designed to diagnose an abnormality, however; they are designed to test whether something looks normal or abnormal and inform you of the risk level. Your doctor will likely recommend additional tests to make a diagnosis.

A perinatologist will likely use a maternal blood test to check your pregnancy hormone levels and a nuchal translucency measurement, which uses an ultrasound to measure fluid levels in the space behind the baby’s neck. This information, when combined with the mother’s age and other risk factors, can give a perinatologist a good idea of your risk level.

Mothers who will be 35 or older at the time of delivery will likely get recommended for further testing. These tests can include amniocentesis and chorionic villus sampling.

Prenatal Testing at Valley Perinatal Services

Expectant high-risk mothers and their children can benefit from additional genetic testing to screen for life-changing complications. For mothers and their obstetricians in the Phoenix area, Valley Perinatal Services can help co-manage pregnancies and perform tests.

Our staff includes experienced perinatologists and other specialists trained to respond to your unique challenges and uncover potential problems. Our state-of-the-art technology and training will help you achieve better outcomes and maintain your peace of mind.

Whether you’re looking for ultrasound imaging, genetic counseling, or screening procedures, we can develop a plan that works for you. For more information, call our team at 480.756.6000 or schedule an appointment online.