'At Risk' Pregnancies

Reviewed on 20/10/21

It is important to inform us if there is a known family history of any of the diseases we currently screen for, including results of any prenatal testing. This avoids unnecessary duplication of follow-up or diagnostic testing, and helps avoid any confusion arising from screening results which might cause concern for the family. Please contact the laboratory with the mothers details and expected due date.


Inherited Metabolic Diseases (IMDs)

A new sibling born to the same parents when an index case with PKU, MCADD, MSUD, IVA, GA1 or HCU has already been identified has a 1 in 4 risk of having the same disorder. In these circumstances it is good practice to test earlier than the 5-8 day timeframe for newborn screening to avoid delays in diagnosis and to allay parental anxiety. However, this does not remove the need for routine screening and it is essential that the routine blood spot collection is undertaken between 5 and 8 days to screen for the other conditions tested for as part of the newborn blood spot programme.

The decision about when to test depends upon the conditions suspected; it is most pressing for disorders such as MSUD, MCADD and IVA which can potentially have an early neonatal presentation and may be at risk.


When to test and samples taken

(Write details on request/bloodspot card e.g. Family history of PKU, and courier to the laboratory using urgent/next day delivery)

Family History of....

Early sample timing

Sample types


48 - 72 hours

Phe (bloodspot)


24 - 48 hours

C8 (bloodspot), Urine organic acids, Genotyping


12 - 24 hours

Alloisoleucine (plasma) and Urine organic acids


24 - 48 hours

C5 (bloodspot) and Urine organic acids


24 - 48 hours

Bloodspot acylcarnitines (C5 - DC), Urine organic acids, Genotyping


early testing not required

Plasma amino acids and total homocysteine may be collected after 3 days


Resources for IMDs


Sickle Cell Diseases (SCD)

The Sickle Cell and Thalassaemia screening programme is the world's first linked screening programme. Positive antenatal results are communicated to us by midwives and screening team personnel, using an alert form (available from local screening coordinators). This means we are prepared for any babies 'at risk' of Sickle Cell Disease and can tailor advice with parental history.

Cystic Fibrosis (CF)

Please note, the CF screening programme is designed to detect babies who have cystic fibrosis and will not identify all CF carriers.

Contact Newborn Screening

Newborn Screening Laboratory (Bristol)
PO Box 407

Email: nbn-tr.newbornscreening@nhs.net
Telephone: 0117 414 8412


Opening times: 9am - 5pm Monday - Friday excluding bank holidays.

Clinical advice & interpretation is available during working hours.

Access the NHS Blood Spot Screening Programme Centre