Optimal Follicle Count for IUI: Balancing Successes and Risks

What is IUI?

Intrauterine insemination, or IUI, is a type of fertility treatment that helps to increase your chances of pregnancy by placing your partner’s sperm directly into your womb. This procedure is less invasive and is usually recommended as part of initial treatment for couples facing unexplained infertility.

What is a mature follicle?

A mature follicle is a fluid-filled sac in the ovary that contains a fully developed egg ready for ovulation. The average diameter of a mature follicle is typically between 18 and 25 millimeters. These follicles are also known as dominant follicles or De Graaf follicles.

Mature follicles are composed of several parts:

• The oocyte (egg cell) surrounded by a zona pellucida

• A fluid-filled cavity is visible on ultrasound

• Concentric layers of cells are present, including granulosa cells and theca interna and externa cells.

During a natural menstrual cycle, usually only one follicle reaches full maturity and releases its egg during ovulation, which occurs around day 14 of the cycle. Fertility specialists may give you medications to stimulate the ovaries, making them produce more than one egg.

The size of the follicle is a crucial indicator of egg maturity and readiness for fertilization. Fertility specialists use follicle size measurements to determine the optimal timing for egg retrieval in IUI procedures or to predict natural ovulation.

When do I need IUI with more than 1 follicle?

IUI with 2 follicles is often recommended when there is a need to increase the chances of conception due to situations such as when you and your partner are experiencing unexplained infertility, mild male factor infertility, or mild endometriosis. It can also be suggested when previous IUI attempts with a single follicle were unsuccessful.

What does IUI with an increase in follicle count mean?

IUI with an increase in follicle count means that the process of artificial insemination of sperm is directly placed into your uterus when you have more than 1 mature follicle. Therefore, multiple ovarian follicles can supply the egg for fertilisation following the artificial insemination procedure. This increases the likelihood of a successful conception during the IUI cycle compared to a single follicle cycle.

How many follicles do I need for a successful pregnancy?

The success of IUI can often depend on the number of follicles present during the treatment. Usually, IUI with 2 follicles is considered by many fertility specialists to be better in improving the chances of pregnancy, compared to just one follicle. The presence of two mature follicles increases the likelihood of fertilisation and conception because it provides multiple opportunities for the sperm to meet the egg.

Similarly, the size of the follicle is crucial for successful fertilisation. The ideal follicle size for IUI is usually between 18 and 22 mm. A follicle that is too small may contain an immature egg that is not ready for fertilisation, while a follicle that is too large may indicate postmaturation, reducing the egg's viability.

It's important to have a thorough consultation with your fertility specialist to determine if IUI is suitable for you. Request a consultation with our fertility specialist at the Thomson Fertility Centre for personalised recommendations and tailored advice.

Are there any risks?

When you have a higher mature follicle count, your chances of having twins are higher, as each follicle has an egg; if more than one egg gets fertilised, you could end up pregnant with twins. However, more than 60% of twins are born prematurely, and twin pregnancies carry a higher risk of miscarriage, congenital disabilities, gestational hypertension, and anaemia.

To balance pregnancy success with the risks associated with multiple pregnancies, many fertility specialists recommend:

1. Limiting IUI cycles to no more than two mature follicles for women under 40.

2. Considercancelling IUI cycles if more than three follicles mature, due to the increased risk of higher-order multiples.

3. Individualising treatment based on factors such as age, fertility history, and patient preferences.

Remember, every patient's situation is unique, and decisions should be made in consultation with a fertility specialist who can provide personalised advice based on individual circumstances.

The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice, please consult a specialist at Thomson Medical. Book an appointment with Thomson Medical today.

FAQ

What is the success rate of IUI with 3 follicles?

Often, we depict the success rates for IUI procedures as the pregnancy rates per cycle. For women in the 18-35 age-group, the success rate of IUI with 3 follicles may range between 10% and 20% per menstrual cycle

Is a 25mm follicle too big for IUI?

The size of the follicle is also an important factor  for the IUI success rate. Multiple studies have demonstrated that the ideal follicle size to improve the likelihood of pregnancy is 18–22 mm.

What is the ideal number of follicles for IUI?

Increasing the number of mature follicles from 1 to 5 at the time of IUI in women under 38 years of age increased the clinical pregnancy rate from 14.6% to 21.9%.

Which round of IUI is the most successful?

Statistics show that the majority of IUI pregnancies occur in the first three to four cycles of IUI. One study concluded that 88% of all successful IUIs happen within three cycles and 95% within four. Another study found that 90% of IUI pregnancies occur in the first three cycles of IUI.

What increases the success of IUI?

To enhance your chances with IUI, some helpful choices are adopting a healthy lifestyle. It can positively impact your chances of success with IUI. Prioritise regular exercise, manage stress levels, and get adequate sleep to optimise your overall well-being.

Does multiple follicles mean twins?

If several eggs are released and are fertilised by your partner's sperm, you will have an increased chance of multiple pregnancies.

The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice, please consult a specialist at Thomson Medical. Book an appointment with Thomson Medical today.