What is the percentage chance of achieving pregnancy with each Intrauterine Insemination (IUI) cycle?

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Success Rates of Intrauterine Insemination (IUI)

The average delivery rate per IUI cycle is approximately 8.3% with homologous semen, though success rates vary based on factors such as age, infertility diagnosis, and use of ovarian stimulation. 1

Success Rates by Cycle Type

Natural Cycle IUI

  • Delivery rate: Approximately 8.3% per cycle with homologous semen 1
  • For donor semen: Approximately 12.2% per cycle 1
  • IUI alone in natural cycles (without ovarian stimulation) shows limited effectiveness for unexplained infertility 1

Stimulated Cycle IUI

  • With clomiphene citrate: Average pregnancy rate of 7% per cycle 2
  • With FSH ovarian stimulation: Average pregnancy rate of 12% per cycle 2
  • Adding ovarian stimulation to IUI significantly increases live birth rates in couples with unexplained infertility 1

Factors Affecting Success Rates

Number of Follicles

  • One follicle: 7.6% chance of conception
  • Two follicles: 26% chance of conception 3
  • Increasing mature follicles from one to five in women under 38 increases clinical pregnancy rates from 14.6% to 21.9%, but primarily due to multiple gestations 4

Sperm Parameters

  • Progressive motility significantly impacts success 3
  • Total motile sperm count (TMSC) > 10 million shows better outcomes 1

Duration of Infertility

  • Longer duration of infertility correlates with lower success rates 3

Endometrial Thickness

  • Optimal endometrial thickness significantly improves success rates 3

Cumulative Success Rates

  • At least three consecutive IUI cycles should be performed to maximize chances 1
  • Most pregnancies (81%) occur within the first two treatment cycles 5
  • In one study of women with antisperm antibodies:
    • Unstimulated cycles: 13% pregnancy rate overall (3% per cycle)
    • Clomiphene citrate cycles: 30% pregnancy rate overall (7% per cycle)
    • hMG stimulation cycles: 39% pregnancy rate overall (11% per cycle) 5

Multiple Gestation Risk

  • Multiple delivery rate: 11.1% with IUI compared to 20.2% with IVF/ICSI 1
  • In women under 40 with more than three mature follicles, over 25% of pregnancies result in multiples 4
  • Risk increases dramatically with follicle number:
    • One follicle: 3.9% twin rate, 0.2% higher-order multiples
    • Five follicles: 23.3% twin rate, 10.6% higher-order multiples 4

Optimizing IUI Success

  1. Number of inseminations per cycle: Single insemination is recommended as evidence does not support improved outcomes with double insemination 1, 6

  2. Timing of insemination:

    • When using hCG trigger: Perform IUI 24-40 hours after injection
    • In natural cycles: Perform IUI 1 day after LH surge 1

  3. Post-procedure protocol:

    • 10-15 minutes of bed rest after insemination is recommended 1

  4. Cycle management:

    • Cancel cycle or convert to IVF when more than two follicles >15mm or more than five follicles >10mm are present to reduce multiple pregnancy risk 1
    • Use lower doses of gonadotropins (75 IU or less) to minimize multiple pregnancy risk 1

Important Caveats

  • Success rates vary significantly based on the cause of infertility
  • Stimulated IUI is ineffective in male factor infertility 2
  • Women over 40 may benefit from up to four follicles without substantially increasing multiple gestation risk 4
  • Patients should be informed about possible increased risks of preterm birth and low birthweight compared to spontaneous pregnancies 1

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

2
Research

Intrauterine insemination.

Human reproduction update, 2009

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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