Screening tests are used to assess the chance of your baby having a chromosomal or structural condition. If a screening test suggests an increased chance of a particular condition, a diagnostic test is performed to find out if the condition is actually present. Around 2% of all babies are born with some kind of abnormality. Most are minor, such as fused toes or skin tags. However, a very few babies will have more major problems, such as heart defects, spina bifida and chromosomal irregularities. In most cases, screening tests provide reassurance that everything is OK. The National Screening Unit oversees pregnancy and newborn screening in New Zealand.

A maternal blood test between 9 and 14 weeks of pregnancy is combined with a scan between 11 and 14 weeks. The data obtained from these combine to calculate the risk of the baby being affected by Down syndrome and other rarer related syndromes.

The result is expressed as a probability of the baby being affected. When a result is low probability, reassurance can be given. When a result is high probability, further testing can be considered. Further testing is either non-invasive (see NIPT), or invasive (a needle passes into the pregnancy to collect a genetic sample).

If women miss the 14 week cut-off for MSS1 testing, there is still the option to do a second trimester standard genetic screen (MSS2) and/or NIPT.

NIPT has been available for women in New Zealand since 2014. A maternal blood sample contains fragments of placental material, which are able to be analysed for genetic disorders affecting the placenta and the baby.  It is far more sensitive and accurate than MSS1 and MSS2, and can also determine the sex of the baby. NIPT is funded if a high risk MSS1 result occurs, otherwise the cost is paid for by the patient.

Origins preferred NIPT provider is at www.sequenca.nz

This is the 'big scan', performed between 19 and 21 weeks, at the stage your baby is large enough to allow accurate anatomical assessment. During this scan you are able to confirm the sex of the baby, but only if you want to know! The scan is able to detect nearly all major and minor birth defects if present, and also checks the development of the placenta.

Following a complete anatomy scan your baby grows and grows, and at each visit to Origins your obstetrician will perform a scan checking baby's size, position and fluid level.  If your pregnancy is complicated by conditions such as high blood pressure or diabetes, these scans are especially important and additional scans independent of those at Origins may be recommended.

Should your pregnancy become particularly complicated, you may require medical checks up to three times per week. In these cases, we may make use of the Day Assessment Unit at National Women's Hospital, to keep you and your baby under close and frequent observation.