Beyond the first trimester screen: can we predict who will choose invasive testing?

PURPOSE: The purpose of this study is to determine what factors, in addition to a positive first trimester aneuploidy screen, correlate with a pregnant patient's decision to undergo invasive prenatal testing.

METHODS

We conducted a retrospective cohort study of singleton pregnancies referred to the Johns Hopkins Prenatal Diagnosis and Treatment Center between 2001 and 2009 with an indication of positive first trimester screen. We compared demographic factors and numerical first trimester screen results with invasive testing uptake. Risk difference calculations and linear modeling were used for analysis.

RESULTS

A total of 171 eligible patients were identified. Maternal age, race, residual risk, marital status, and year of first trimester screen correlated significantly with invasive testing uptake. Family history was predictive of invasive testing uptake for patients younger than 35 years only. Type of elevated risk (trisomy 21 vs. 18 and 13), assisted reproductive technology status, parity, and increase from age-related risk were not predictive. A general linear model for relative risk with Gaussian error showed significant interaction between the variables of age and family history, so the two traits were analyzed separately (P = 0.009).

CONCLUSIONS

Among patients with positive first trimester screen results, several demographic traits are predictive of invasive testing uptake. This information can help providers to identify patients at increased risk of declining invasive testing and can help providers anticipate educational needs. Further investigation should be conducted to elucidate the causes of these differences, which may relate to misinformation about the testing options and differences in values systems.