Screening for chromosomal abnormalities is also possible employing non-invasive methods using a blood sample (a test known as NIPT) which is recommended for intermediate-risk pregnancies. Alternatively, invasive prenatal diagnosis (IPD) may be carried out by collecting a sample of the baby’s tissue: choriocentesis from the 11th week of pregnancy (chorionic villus sampling, or CVS), or amniocentesis from the 15th week of pregnancy (sampling of the amniotic fluid). The risks of miscarriage linked with invasive diagnosis were overestimated in the past, and are of the order of one in 200 procedures.

The other genetic risks for pregnancy, apart from chromosomal abnormalities, are certainly less significant, but must be considered when chromosomal analysis is normal, and when, for example, a malformation or unexplained characteristic has been detected in the baby. These anomalies are, in particular, associated with chromosomal rearrangements (link) and gene mutations (link).

Chromosomal rearrangements are either transmitted either by a parent or they occur for the first time in the baby, which is generally a less favourable scenario. We are all healthy carriers of at least three of these rearrangements, so they are not necessarily harmful; for this reason, it is important to talk to the team of genetics specialists.

As regards gene mutations, these may occur for the first time in the baby without being present in the parents' genetic make-up or, alternatively, one or other of the parents carries the mutation. The implications must be addressed based on the nature of the gene and its transmission; our team is at your disposal to discuss this.

Genesupport - Risk of pregnancy