How many women have prenatal testing for Down syndrome?

Sequenom's MaterniT21, et al., booth

Sequenom’s MaterniT21, et al., booth

A recent study calculated how many women in the United States have prenatal screening for Down syndrome. It’s a growing number. 

Glenn Palomaki led a team surveying testing laboratories to find out how many women in the United States are having prenatal testing for Down syndrome (here’s the full report). Palomaki has made a career in developing screening tests for Down syndrome, and was the lead author on the study Sequenom relied on to launch MaterniT21 in 2011.

Here’s what Palomaki and his team found about the rate of prenatal screening for Down syndrome in the United States:

  • In 1988, a study found that about 25% of all pregnancies in the United States had prenatal screening for Down syndrome.
  • In 1992, that number rose to be about 50% of all pregnancies being screened.
  • Palomaki’s study found that in 2011-2012 up to 72% of all pregnancies were screened for Down syndrome.

The study provided a further breakdown of what type of prenatal screening women were having:

  • 60% received second trimester screening, usually quad testing.
  • 21% had integrated screening making it the second most common.
  • First-trimester screening rose from 7% in 2011 to 19% in 2012.

The breakdown in the type of tests is somewhat surprising.

Since 2007, all women are to have been offered prenatal screening for Down syndrome, with the professional guideline making this recommendation being prompted by the advent of first-trimester prenatal screening. In 2009, a survey of obstetricians found a “new paradigm” with OBs offering prenatal testing to all of their patients. Yet, four years after the recommendations, and two years after the “new paradigm,” Palomaki et al.’s study found that 60% of all pregnancies having screening were done in the second trimester, not the first.

One other point about the Palomaki study: it’s already outdated.

As mentioned at the start, Palomaki’s other study in 2011 launched the new era of prenatal testing with non-invasive prenatal screening (NIPS). But, none of the labs surveyed included the NIPS labs.

Palomaki’s et al’s study is of interest as it is the most recent calculation of the percentage of women undergoing prenatal screening for Down syndrome in the United States. But, it represents a snapshot of an era of prenatal screening that is now incomplete, since NIPS is increasingly being accepted by expectant mothers. Palomaki et al.’s study recognizes this in its conclusion.

It will be of interest to see any follow up report from 2013-2014 that includes the NIPS laboratories to see how NIPS has changed the rate of uptake of women accepting prenatal screening for Down syndrome, and in what trimester they do so.

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