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Number of follicles as a risk factor for multiple pregnancy with IUI cycles

Posted on September 22, 2020 by Inception Fertility

Infertility Article Review and Discussion

Title: Relationship of Follicle Numbers and Estradiol Levels to Multiple Implantation in 3,608 Intrauterine Insemination Cycles

Authors: Richard P. Dickey, Steven N. Taylor, Peter Y. Lu, Belinda M. Sartor, Phillip H. Rye, and Roman Pyrzak

Source: Fertility and Sterility, January 2001, Vol. 75, pp. 69-78

Background on Ovarian Stimulation for Infertility and Multiple Birth Risks

Multiple pregnancy, particularly triplets and higher, poses significant risks. In fertility treatments involving ovarian stimulation, the challenge lies in maximizing pregnancy chances while minimizing risks of multiple pregnancies.

  • What’s the balance between aggressive ovarian stimulation and multiple pregnancy risks?
  • How many follicles should ideally mature, and does this differ by age?
  • What impact do drugs, estrogen levels, and age have on pregnancy outcomes?

Study Objective and Methods

The study aimed to determine the relationship of follicle numbers and estradiol (E2) levels to multiple implantations in cycles involving Clomid and injectable medications.

  • Sample Size: 3,608 cycles analyzed
  • Medications: Clomid, HMG (injectable gonadotropins), or both
  • Outcome Measures: Pregnancy rates, multiple implantation rates

Data included follicle counts, estradiol levels, and outcomes of pregnancy (single, twin, triplet, or higher-order pregnancies).

Results: Key Findings on Stimulation Types and Outcomes

Clomiphene Citrate Cycles (Clomid)

In Clomid cycles, 8.0% were twin pregnancies, and 1.7% were triplet or higher-order pregnancies. Pregnancy was closely related to follicle count (≥15mm) rather than estrogen levels or age.

HMG Injectable Cycles and Clomiphene + HMG Cycles

For HMG cycles, 11.2% were twin pregnancies, and 7.2% were triplets or higher. Pregnancy correlated with follicle counts (≥12mm) and estrogen levels, with age negatively impacting success.

Impact of Age on Pregnancy and Multiple Implantations

Age influenced pregnancy rates and implantation outcomes, with younger women facing higher multiple pregnancy risks with more follicles, while older women showed improved pregnancy rates without a significant rise in multiple implantations.

Effect of Estradiol (E2) Level

Higher E2 levels (>1000 pg/mL) in HMG and Clomiphene + HMG cycles increased the chance of triplet and higher-order pregnancies by fivefold compared to lower levels.

Critical Findings on Follicle Counts and Pregnancy Risks

The study highlighted critical thresholds where pregnancy success and risks for multiple implantations balanced.

  • For younger patients (<35), triplet pregnancies increased when six or more follicles >12mm and E2 levels exceeded 1000 pg/mL.
  • Older patients showed doubled pregnancy rates with six or more follicles, without increased triplet risks.

Study Conclusions

Withholding HCG when six or more follicles (>12mm) are present may reduce triplet and higher-order pregnancies by 67% for patients under 35, without affecting overall pregnancy rates. For patients over 35, similar measures may reduce pregnancy rates by half without affecting multiples significantly.

Comments by Dr. Sherbahn

Infertility treatments must balance pregnancy success with risk avoidance. Studies like this guide specialists in deciding when to proceed or cancel cycles with high-risk profiles.

We aim for successful pregnancies while carefully managing multiple birth risks...

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      Welcome to the Advanced Fertility Center of Chicago’s blog! Here, you will find information on the latest advancements in fertility care and treatments, including IVF, IUI, third-party reproduction, LGBTQ+ family building, preimplantation genetic testing, and more. Since 1997, we’ve used our experience and continuous investment in the latest fertility technology to help thousands of patients grow their families. Contact us today for more information or to schedule a new patient appointment.