Non-invasive PGT-A did not improve pregnancy rates

A non-invasive form of preimplantation genetic testing for aneuploidy (PGT-A) did not improve pregnancy rates in a clinical trial, but did reduce early miscarriages.

Normally, PGT-A is done by taking a biopsy of cells from a blastocyst and looking at their chromosomal content. However, in non-invasive PGT-A (niPGT-A), cell-free DNA is taken from the culture media in which the embryos are grown instead. A double-blind study by Chinese researchers compared pregnancy rates and outcomes among patients whose embryos were assessed using niPGT-A or standard appearance-based morphology criteria.

'The results indicated that there was insufficient evidence to establish a statistically significant difference in [ongoing pregnancy rate]', said the researchers in their paper published in Nature Communications. 'The results of this trial do not provide a basis for recommending routine use of niPGT-A in this good-prognosis population.'

In the trial, 1152 female fertility patients aged 35-42 were recruited from 13 fertility centres across China. They were randomised into two groups to have embryos selected for transfer: one group used niPGT-A and the other used standard morphology criteria.

The researchers looked at the ongoing pregnancy rates (pregnancies proceeding past 12 weeks) as well as rates of clinical pregnancies, live births and miscarriages. In the niPGT-A group, the ongoing pregnancy rate was 38.7 percent and live birth was 37 percent versus 36.8 percent and 35.5 percent, respectively, in the morphology group. These differences, as well as those in clinical pregnancy rates, were not statistically significant.

However, the niPGT-A group had lower miscarriage rates. The differences in miscarriages before 12 weeks (18 percent compared with 25.2 percent in the morphology group) were statistically significant, but those occurring between 12 and 28 weeks were not. There were also no significant differences in maternal or neonatal outcomes, and no serious adverse events in either group.

PGT-A is already controversial (see BioNews 1320). The Human Fertilisation and Embryology Authority says it does not improve the likelihood of a live birth for most patients, but may reduce the chance of miscarriage. The American Society of Reproductive Medicine's position is that 'the value of PGT-A as a routine screening test for all patients undergoing in vitro fertilisation has not been demonstrated'.

The study did not include a standard PGT-A group, so conclusions cannot be drawn about how niPGT-A compares.