Nub Theory for IVF Pregnancies: Does It Work Differently?
If you conceived through IVF, you might be wondering whether nub theory works the same way. The good news: it does. Nub theory is based on fetal development, not how the baby was conceived.
Table of Contents
- Does IVF Affect Nub Theory?
- Timing for IVF Pregnancies
- Accuracy for IVF
- Special Considerations
- Frequently Asked Questions
Does IVF Affect Nub Theory?
No. Nub theory works the same way regardless of whether you conceived naturally or through IVF. The genital tubercle develops at the same rate and the angle is assessed the same way.If you had PGT-A (preimplantation genetic testing) during IVF, you may already know your baby's sex — PGT-A identifies the sex chromosomes of embryos before transfer. In this case, nub theory is a fun confirmation rather than a prediction.
Timing for IVF Pregnancies
For IVF pregnancies, your due date is calculated from the transfer date: - Day 5 transfer: Add 261 days to transfer date - Day 3 transfer: Add 263 daysYour 12-week scan timing is the same — between 11+2 and 14+1 weeks by IVF dating.
Accuracy for IVF
Nub theory accuracy for IVF pregnancies is the same as natural conceptions: 80-95% at 12+ weeks. The method doesn't change based on conception method.Special Considerations
1. **You may already know the sex**: If you had PGT-A, you already know the sex chromosomes 2. **Anxiety levels may be higher**: IVF mums often have higher pregnancy anxiety — remember nub theory is just for fun 3. **Early scans are common**: IVF mums often have more early scans, but nub theory still only works at 11-13 weeks 4. **Donor eggs/sperm**: If you used donor eggs or sperm, nub theory works the same wayFrequently Asked Questions
### If I had PGT-A, do I need nub theory?If you had PGT-A testing during IVF, you already know your baby's sex chromosomes with near-100% accuracy. Nub theory would just be a fun way to see if the scan matches what you already know.
Does IVF make the baby develop differently?
No. IVF babies develop at the same rate as naturally conceived babies. The genital tubercle develops on the same timeline, so nub theory timing and accuracy are identical.
This article is for informational purposes only and does not constitute medical advice.
Last reviewed: June 2026
Related articles: