IVF (In Vitro Fertilisation)
Last updated: March 2026
What is IVF?
IVF stands for in vitro fertilisation. “fertilisation that takes place outside the body” (HFEA, 2021). Eggs are collected from the ovaries, fertilised with sperm in a laboratory, and the resulting embryo is placed in the womb (NHS, 2024).
How it works
IVF follows nine steps: ovarian suppression, hormone stimulation (daily injections for 10-14 days), ultrasound monitoring, trigger injection, egg collection under sedation, fertilisation, embryo culture to blastocyst stage (day 5-6), embryo transfer, and a pregnancy test roughly two weeks later (HFEA, 2021).
Fertilisation can use standard IVF or ICSI, where a single sperm is injected directly into the egg. Some clinics also offer PGT-A screening before transfer. Surplus embryos can be vitrified for future frozen embryo transfer.
The full cycle takes 4-6 weeks from the first injection to the pregnancy test. Most patients need 2-3 cycles. The stimulation drugs are the physically demanding part: bloating, mood swings, injection fatigue. Egg collection is done under sedation and takes about 30 minutes. The transfer itself is painless (NHS, 2024).
Success rates by age (HFEA 2021, fresh transfer)
| Age | Birth rate per cycle | Pregnancy rate |
|---|---|---|
| 18-34 | 33% | 41% |
| 35-37 | 25% | 33% |
| 38-39 | 17% | 25% |
| 40-42 | 10% | 16% |
| 43-50 | 4% | 6% |
(HFEA, 2021)
The gap between pregnancy rate and live birth rate is roughly 8 percentage points across age groups. Clinics that advertise pregnancy rates instead of birth rates are showing you the flattering number. Always ask for live birth rates per embryo transfer, broken down by your age group.
With donor eggs, birth rates stay above 30% regardless of the recipient’s age (ESHRE EIM, 2019). The egg’s age matters, not the womb’s.
What to ask your clinic
- What is your live birth rate for my age group with fresh transfers?
- Do you recommend ICSI or standard insemination for my case?
- How many embryos will you transfer. Do you practise single embryo transfer?
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Related research
- Can your first hCG blood test predict IVF success?: what early blood results can and can’t tell you.
- Time-lapse imaging doesn’t improve live birth rates: the TILT trial on whether watching embryos grow helps pick better ones.
Sources
- HFEA. In Vitro Fertilisation (IVF): https://www.hfea.gov.uk/treatments/explore-all-treatments/in-vitro-fertilisation-ivf/
- NHS. IVF: https://www.nhs.uk/conditions/ivf/
- HFEA. Fertility Treatment 2021: Preliminary Trends and Figures: https://www.hfea.gov.uk/about-us/publications/research-and-data/fertility-treatment-2021-preliminary-trends-and-figures/
This page is for informational purposes only and does not constitute medical advice. Always consult a qualified fertility specialist before making treatment decisions.