FAQs - Section 6: Requesting Harmony
We recommend that the test be done between 10 and 14 completed weeks’ gestation.
The Harmony Prenatal Test relies on there being sufficient fetal DNA in the maternal circulation for analysis. The concentration of fetal DNA rises during pregnancy. The particular time at which the fetal DNA concentration is high enough for detection will vary from woman to woman.
In practice, Harmony should not be offered to women who have not completed 10 weeks’ gestation. More than 95% of women will have sufficient fetal DNA for analysis after this gestation. Harmony has not been validated at an earlier gestation.
The fetal DNA concentration rises slowly between 10–20 weeks of gestation. Deferring Harmony for 1–2 weeks may reduce the chance of the woman having an undetectable fetal DNA.
Harmony can be performed at any time after the 10th completed week of pregnancy. However, the usefulness of information obtained after 20 weeks may be limited by other factors, such as the intervention options available at later gestations.
The laboratory needs to have accurate information about gestation and the presence of twins so that the Harmony test can be reported. Thus, we strongly recommend that a dating scan is performed to confirm gestational age, viability and number of fetuses before the Harmony test is ordered.
We accept Harmony requests from the following healthcare practitioners:
- A medical practitioner who is accountable for the care provided to a pregnant woman
- A midwife or other allied health professional working as part of the team environment in which a doctor has overall accountability for the care provided to an individual patient
Harmony is an important test that carries significant implications for the patient and her baby. Our policy is to support clinicians who are accountable for the care provided to pregnant women. We do not accept test requests from patients themselves, or from clinicians who are not responsible for the woman’s care.
The Australian regulatory authorities stipulate that a genetic test for medical purposes can only be requested as part of a medical consultation. This requirement prevents us from accepting Harmony requests from non-medical healthcare professionals, such as independent practising midwives and genetic counsellors. We encourage independent non-medical healthcare professionals to develop a suitable relationship with a medical practitioner to facilitate the inclusion of Harmony in a patient’s care.
We require a special request form to ensure that we obtain the required information to interpret the analytical result correctly. The Harmony Prenatal Test will not be performed unless the special request form is received and signed by the referring doctor and the patient (signatures from both are required). Note that the request forms are available on most practice management software systems and also as a PDF on the Sonic Genetics website. Please contact us for further information.
The decision about which date is more likely to be correct must be resolved by the doctor responsible for managing the pregnancy. Harmony does not provide any information regarding this.
If a woman has different estimated dates for delivery, it may be preferable to defer Harmony until a gestation of 10 completed weeks, calculated according to the later date. In other words, it is usually preferable to err on the side of taking a sample for Harmony later rather than earlier.
The Harmony test assumes that the mother has normal chromosomes and normal amounts of DNA in her blood. Any maternal condition which compromises these assumptions could make the Harmony test less accurate. Maternal conditions that could compromise the accuracy of Harmony include Triple X syndrome, mosaic chromosome disorder, cancer and marrow or organ transplantation. Harmony has not been validated in these settings.