Age and IVF success
Where clinic-mean live-birth rates fall across CDC age bands, why egg quality drives the swing, and how to read those numbers without mixing case mix.
Disclaimer: This guide is for informational purposes only. It does not constitute medical advice. Age is one factor among many that affect IVF outcomes. Always consult a reproductive endocrinologist for guidance specific to your situation.
Age bands · CDC NASS clinic means
Clinic means in this NASS extract fall from 48% under 35 (399 clinics) to 8.8% at patients over 40 (303 clinics); about a 5.5× swing between those brackets; egg quality, not uterine age, drives most of that gap.
- 48%
- Under 35 mean (399 clinics)
- 22.5%
- Ages 38–40 mean (355 clinics)
- 8.8%
- Over-40 mean (303 clinics)
- 5.5×
- Under-35 ÷ over-40 ratio
Each band average covers only clinics that published that bracket; denominators differ. Means are not a personal probability.
Live clinic means by age band
Same NASS extract as the success-rates guide: horizontal age-band means plus the under-35 ÷ over-40 swing gauge. No hand-typed national ranges.
Clinic-mean live-birth rate by CDC age band
Averages across clinics that publish each band in this extract.
Under-35 ÷ over-40 mean ratio
Same extract: 48% ÷ 8.8% · about a 5.5× swing. Donor-egg cycles are reported separately by CDC.
Clinic counts per bar: Under 35 n=399 · 35–37 n=358 · 38–40 n=355 · Over 40 n=303.
Why age dominates the chart
The age effect in IVF is driven almost entirely by egg quality, not uterine receptivity. The uterus remains capable of carrying a pregnancy well into the 40s, as donor-egg success rates demonstrate. The eggs themselves are the limiting factor.
As eggs age, meiosis becomes more error-prone, producing eggs with too many or too few chromosomes (aneuploidy). Aneuploid embryos typically fail to implant or result in early miscarriage. IVF and PGT-A can help select chromosomally normal embryos when they exist; they cannot create normal embryos from abnormal eggs.
Ovarian reserve also declines with age, so older patients often retrieve fewer eggs per cycle. Fewer eggs plus higher aneuploidy rates means fewer transferable embryos, one reason older patients often need multiple cycles.
How to read the live bands above
- Under 35 - highest clinic-mean live-birth rates in this extract (about 48%).
- 35–37 - still relatively strong (about 35.3%).
- 38–40 - meaningful decline (about 22.5%).
- Over 40 - much lower with own eggs (about 8.8%).
Critical rule: only compare clinics within the same CDC age band. Mixing under-35 rates with overall or over-40 rates invents a false ranking.
What this means when you shortlist clinics
Use PlainFertility age-band rates as a discovery filter: shortlist clinics that publish competitive rates in your band, then talk with a reproductive endocrinologist about diagnosis, protocol, and cost. Time sensitivity rises after the mid-30s; after 40, many programs discuss donor eggs earlier because own-egg means fall sharply in the published bands.
Donor-egg cycles reset the egg-age clock: outcomes track the donor’s age far more than the recipient’s. CDC reports those cycles separately, do not blend them into the own-egg band chart above.