IUI and IVF get named in one breath, as if they were two flavours of the same thing. They are not. One treatment lets your body do nearly all the work. The other takes that work over.
When you first hear that a fertility route is coming, that difference is confusing. Terms get thrown at you without the logic behind them. The logic does exist, and it is simpler than you think.
Below I put the two side by side and explain why the order runs the way it does.
What is an IUI treatment exactly?
IUI stands for intrauterine insemination. In the laboratory, sperm is washed and concentrated. That sperm then goes through a thin catheter straight into your uterus, around the time your ovulation is expected. The procedure takes a few minutes and needs no anaesthetic.
Sometimes this happens in your own natural cycle. Sometimes the clinic adds mild stimulation, so one or two follicles ripen. That is a different scale from the full stimulation used in IVF.
So what IUI does is shorten the sperm journey. Nothing more.
Why does IUI only work with your own ovulation and open tubes?
Because IUI does not replace ovulation or fertilisation. The sperm cell still has to swim into your tube and meet an egg there. If your tubes are blocked, they never meet at all. If you do not ovulate, there is simply no egg waiting to be met.
That single sentence explains the whole treatment ladder. IUI is a nudge, not a replacement. IVF is a replacement: there your eggs are collected and fertilisation happens outside your body.
So a clinic checks those two conditions first. Whether your tubes are open is assessed with imaging. Whether you ovulate can be confirmed with a blood test.
Say you have a 32-day cycle and you have been trying for 14 months. The first question is then not which treatment you get. The first question is whether an egg is released each month.
IUI and IVF side by side
The table below lays the two treatments next to each other. They do not differ in goal. They differ in how much they take over from your body.
| Element | IUI | IVF |
|---|---|---|
| What happens | Washed sperm goes into your uterus | Eggs collected, fertilised in the lab, embryo transferred back |
| Where fertilisation happens | In your tube, so inside your body | In the laboratory, outside your body |
| Egg retrieval | No, no puncture | Yes, a puncture under sedation |
| Hormone stimulation | None or mild | Full stimulation with daily injections |
| What it asks of you physically | A few checks and a short procedure | Weeks of injections, many checks, a procedure |
| Condition beforehand | Open tubes and your own ovulation | Also possible without open tubes |
What happens during such a retrieval sits in the article on the IVF egg retrieval. The full route is set out in the explainer on what IVF actually is.
When is the insemination scheduled?
Around your ovulation, which makes timing everything here. Sperm cells survive a limited number of days. An egg lasts far shorter than that. So the clinic looks for the window just before or during your ovulation. It reads that window from your LH surge, from ultrasound scans and sometimes from blood values.
LH rises sharply just before your ovulation. That surge is the starting gun a clinic waits for. Oestradiol climbs in the days before it and says something about how your follicle is ripening.
Whether ovulation really happened only shows afterwards. A progesterone measurement in the middle of your luteal phase shows whether your ovary has switched over. How that confirmation works sits in the piece on confirming your ovulation with a blood test.
Which day suits you is your doctor to decide. We measure, the clinic plans.
Which blood values matter here?
Mostly the hormones that steer your cycle. LH marks the moment of your ovulation. Oestradiol follows how your follicle ripens. Progesterone confirms afterwards that ovulation took place. AMH says something about your egg reserve, and that weighs mainly on the IVF side.
A meta-analysis found no convincing difference between AMH and the antral follicle count as a predictor of your response to stimulation (PMID 37370145). They tell roughly the same story, each in their own way.
To see those values before your appointment, you can take a fertility assessment. For a wider picture there is the IVF blood test and the complete IVF blood test.
We are a laboratory, not a clinic. We deliver numbers, not a treatment plan.
Is more intervention automatically better?
No, and for me that is the heart of this story. A Cochrane review compared ICSI with conventional IVF in couples without a male factor. No live-birth advantage was demonstrated (RR 1.11, 95% CI 0.94 to 1.30, low certainty, PMID 37581383). So more technique is not automatically more chance.
On the IVF side the numbers are mapped well. In a cohort of 156,947 women, the live-birth rate after a first cycle sat near 32 percent under the age of 40 (PMID 26717030). Between 40 and 42 it was about 12 percent.
That chance also accumulates across attempts. A population study of 178,898 women saw a cumulative live-birth rate of 42.3 to 57.1 percent after three complete cycles (PMID 26783243). What shifts your odds per attempt sits in the article on IVF success rates.
Why a clinic still chooses ICSI in some cases is covered in the difference between IVF and ICSI.
When does it count as subfertility?
The Dutch NHG guideline on subfertility draws a clear line: no pregnancy after twelve months of unprotected intercourse. That is a definition, not an alarm. Thuisarts uses the same line in its patient information. It is the point where a conversation with your GP becomes reasonable, nothing more.
I like that line, precisely because it is so level-headed. It says nothing about your personal odds. It only says when it is fair to start looking.
If you are unsure whether you are there yet, this piece on when to have your fertility tested helps you along.
What is a sensible next step?
Start with the two conditions that decide everything. Are you sure you ovulate each month? That can be confirmed with a progesterone measurement in the middle of your luteal phase. Take that result to your GP or your clinic, because the conversation gets more concrete with it.
Which treatment suits you is your doctor to decide. I would never tell you to start with IUI, because that choice depends on things blood cannot show.
What my work can do: sharpen the questions before you walk into that consulting room.
References
- Smith ADAC, Tilling K, Nelson SM, Lawlor DA. Live-Birth Rate Associated With Repeat In Vitro Fertilization Treatment Cycles. JAMA. 2015;314(24):2654-2662. PMID 26717030.
- McLernon DJ, Maheshwari A, Lee AJ, Bhattacharya S. Cumulative live birth rates after one or more complete cycles of IVF: a population-based study of linked cycle data from 178,898 women. Hum Reprod. 2016;31(3):572-581. PMID 26783243.
- Cutting E, Horta F, Dang V, van Rumste MME, Mol BWJ. Intracytoplasmic sperm injection versus conventional in vitro fertilisation in couples with males presenting with normal total sperm count and motility. Cochrane Database Syst Rev. 2023;8(8):CD001301. PMID 37581383.
- Liu Y, Pan Z, Wu Y, Song J, Chen J. Comparison of anti-Müllerian hormone and antral follicle count in the prediction of ovarian response: a systematic review and meta-analysis. J Ovarian Res. 2023. PMID 37370145.
- NHG guideline on subfertility and the patient information from Thuisarts. Available via nhg.org and thuisarts.nl.
Every blood test result at Lunara includes a professional assessment by a BIG-registered doctor. For treatment decisions, discuss your results with your GP.
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