Abnormal Embryos That Might Not Be So Abnormal After All – Fertility Plus
Fertility Plus shared a post on LinkedIn:
” ‘Abnormal’ embryos that might not be so abnormal after all.
In IVF, we look for two little bubbles of DNA in the egg after fertilisation—two pronuclei (2PN). That’s our classic sign of ‘normal.’ When we see just one (1PN), many labs assume the embryo is abnormal and throw it away.
A new analysis of almost 300,000 embryos tells a different story.
Yes, 1PN embryos are less likely to make it to the blastocyst stage and, if you transfer them without testing, they have lower live birth rates than standard 2PN embryos.
But here’s the twist: when 1PN blastocysts are genetically tested and confirmed to have the right amount of DNA (euploid, diploid, both parents contributing), their chance of a baby looks very similar to tested 2PN embryos.
And the babies? No clear differences in birthweight, gestational age, or congenital malformations between 1PN and 2PN derived births in the studies analysed.
One more nuance: 1PN embryos created with standard IVF seem to do much better than those created with ICSI, which show much lower live birth rates.
What this means for patients:
- If you have very few embryos, that ‘odd’ 1PN blastocyst might still represent a real chance.
- With modern genetic testing, we can identify which 1PN embryos are likely safe to use.
- Decisions should be individual, based on lab expertise and careful counselling.
Science is showing that some embryos deserve a second look—not the bin. Would you want your clinic to consider a carefully tested 1PN embryo if it was your only option?
Lee T, Qi F, Peirce K, et al. To discard or not to discard 1PNs? A systematic review and meta analysis on 291,474 embryos. Reproductive BioMedicine Online. 2026;52(2):105080.”
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