If you have been told to take Estrace or birth control pills before starting an IVF cycle, you may wonder why hormone suppression is used when the goal is to stimulate the ovaries. Although it may seem counterintuitive, fertility cycle priming is an evidence-based approach designed to improve timing, coordination, and overall treatment outcomes.

What Is Fertility Cycle Priming?

Cycle priming refers to the use of hormones—typically estrogen alone (Estrace) or combination birth control pills (estrogen + progestin)—before ovarian stimulation.

According to guidance from the American Society for Reproductive Medicine (ASRM), pretreatment is commonly used to:

• Synchronize follicles
• Schedule cycles predictably
• Suppress ovarian cysts
• Improve visualization before surgery
• Optimize the uterine lining when needed

The goal is to create a controlled and consistent starting point before stimulation begins.

Estrace (Estrogen-Only) Priming

Estrace contains estradiol, a form of estrogen that provides negative feedback to the brain. When estrogen levels are perceived as sufficient, the brain reduces the production of follicle-stimulating hormone (FSH).

Lowering FSH before stimulation allows follicles to develop more evenly, helping them start at a similar size and grow together.

In natural cycles, early elevated FSH levels can lead to uneven follicle recruitment. Estrogen priming helps reduce this variability by:

• Synchronizing follicle size
• Preventing early dominant follicle selection
• Supporting a more coordinated group of follicles at the start of stimulation

Birth Control Pills (Estrogen + Progestin) Priming

Combination birth control pills contain both estrogen and progestin, which work together to regulate the hypothalamic-pituitary-ovarian axis.

These hormones suppress gonadotropin-releasing hormone (GnRH), which in turn lowers luteinizing hormone (LH) and FSH levels. LH suppression is typically more pronounced, creating a temporary “quiet ovary” state.

ASRM-supported evidence shows this approach can help with:

Cycle Scheduling and Synchronization
Allows clinics to better coordinate treatment timing and start stimulation in a controlled manner.

Suppression of Ovarian Cysts
Reduces the likelihood of functional cyst formation before stimulation begins.

Endometrial Preparation
Helps thin the uterine lining, improving visibility for procedures such as hysteroscopy.

The Trade-Off: Suppression vs. Stimulation

A common concern is whether birth control use negatively impacts IVF success.

Research shows that while:

• Slightly higher doses of gonadotropins may be required
• Stimulation may last slightly longer

There is:

• No significant reduction in egg yield
• No consistent decrease in pregnancy or live birth rates

For most patients, cycle priming does not compromise overall IVF success.

How Birth Control Affects AMH and AFC Results

Long-term use of hormonal birth control can temporarily affect ovarian reserve markers.

• Anti-Müllerian hormone (AMH) levels may appear lower
• Antral follicle count (AFC) may be reduced

However, this does not necessarily reflect true ovarian reserve. For more accurate testing, it is generally recommended to stop hormonal contraception 2–3 months before evaluation. In some cases, especially when AFC is very low, a longer break may be advised.

Is Cycle Priming Right for Everyone?

Fertility treatment is highly individualized. Some patients—such as those with PCOS, diminished ovarian reserve, or endometriosis—may require tailored approaches.

This may include:

• Adjusting the duration of pretreatment
• Skipping priming altogether
• Closely monitoring to avoid over-suppression

Cycle priming is a strategic tool, and when used appropriately, it helps create an optimized starting point for ovarian stimulation.

Take the Next Step in Your IVF Journey

If you have questions about cycle priming or your IVF treatment plan, the team at Beverly Hills Fertility is here to help. Our specialists use evidence-based strategies and personalized care to design the most effective approach for your unique needs.

Schedule a consultation today to better understand your treatment plan and take the next step toward building your family with confidence.