If you're diving into the world of assisted reproduction, you've probably stumbled upon the term IVF more times than you can count. But what exactly is it? Well, IVF, short for In Vitro Fertilization, and it is the most powerful and most involved fertility treatment available. It involves a lot of science with a sprinkle of hope, offering many couples a chance to fulfill their dreams of starting a family.

For years IVF has been approached in a very similar manner, by stimulating the ovaries in the first half of the menstrual cycle with or without a prep phase prior. However, a more nontraditional protocol is gaining popularity called Luteal Phase Ovarian Stimulation (LPOS). Contrary to popular belief, this protocol has been around for about decade and has been shown to be a promising alternative to traditional controlled ovarian stimulation protocols. In this blog post we will review the LPOS protocol, discover its benefits, who might benefit from it, and how it differs from traditional IVF protocols.

What is IVF?

IVF is a sequence of highly coordinated steps beginning with controlled ovarian hyperstimulation. Your reproductive endocrinologist will select a protocol to encourage your body to develop multiple egg containing follicles, instead of just the one that typically develops during a natural cycle. Your protocol will often involve daily injections (between 2 – 5 injections per day) of medication for approximately 8 – 14 days. Once the majority of your follicles are above 15mm, ideally between 17 – 20mm your doctor will schedule the egg retrieval. The retrieval of the eggs is timed using a special injection called a trigger. The eggs are then removed from the ovaries under transvaginal ultrasound guidance (no incisions required), and fertilization between the eggs and sperm occurs in the lab.  The embryos are then allowed to grow in the lab to the blastocyst stage at which time genetic testing can be performed to rule out major chromosomal defects or screen for inherited traits such as cystic fibrosis.

Embryos are then frozen for future transfer. After careful preparation of the uterus, the embryo is transferred back into the uterus. which hopefully results in a healthy pregnancy.

What Factors Are Considered in the Selection of a Personalized IVF Stimulation Protocol?

The selection of your personalized stimulation protocol is based on a variety of factors including the results of fertility evaluation, age, antral follicle count, AMH level, and BMI. Additionally, your response to previous ovarian stimulations is a huge factor. If you had an atypical response to medications, many reproductive endocrinologists are going to want to mix up the protocol and try something different for your next stimulation. If you had side effects such as OHSS they are also going to want to do something different to try to prevent this. They'll also factor in any medical conditions you have that might make stimulation riskier. And don't forget about timing – especially if you're preserving fertility due to something urgent like breast cancer.

What is the Luteal Phase Ovarian Stimulation IVF Protocol?

LPOS is a novel approach to IVF that deviates from the conventional long and short protocols. Traditionally, IVF protocols involve suppressing the natural menstrual cycle before ovarian stimulation. However, LPOS utilizes the body's natural hormonal environment during the luteal phase, the period following ovulation and preceding menstruation, for ovarian stimulation.

This is non-traditional protocol is starting to gain popularity amongst IVF clinics for both the typical IVF patient and those who are proceeding with fertility preservation due to a medical condition as there is less of a prep phase. 

How Does Luteal Phase Ovarian Stimulation Work?

The LPOS protocol involves stimulating the ovaries in the second half of your menstrual cycle, typically 2 – 5 days after ovulation has occurred. Because your body naturally ovulates and releases progesterone, ovulation suppression medications can be administered later in the stimulation process. Rather than requiring waiting for the next menstrual cycle to initiate ovarian stimulation, this protocol leverages the inherent hormonal conditions of the luteal phase.

What medications are used?

Similar medications are used in the LPOS protocol to those used in more traditional protocols. In the LPOS protocol, some patients will take Letrozole (an oral tablet) and at least one follicular growth medication. A GnRH Antagonist (such as Cetrotide or Ganirelix) is used towards the end of the stimulation to suppress ovulation. Lastly, hCG or Lupron (or more commonly a combination of the two medications) can be used as a trigger injection to time the egg retrieval.

Benefits of Luteal Phase Ovarian Stimulation

• Minimized Wait Time: Unlike traditional IVF protocols that require waiting for the next menstrual cycle to begin ovarian stimulation, LPOS reduces this waiting period, potentially shortening the overall treatment timeline.
• Reduced Suppression: LPOS minimizes the need for prolonged ovarian suppression, which may be beneficial for certain patient populations, such as women with diminished ovarian reserve or poor responders.

Downside of Luteal Phase Ovarian Stimulation

Unfortunately with LPOS there is no option for a fresh embryo transfer. This is because during LPOS, which takes place in the luteal phase, your uterine lining has already been primed with progesterone. Remember, progesterone is crucial for timing the receptivity of the uterine lining for implantation. When your uterine lining is already exposed to progesterone, it creates a mismatch between the age of the embryo and the readiness of your uterine lining. Additionally, many women are menstruating at the time of egg retrieval with the use of the LPOS protocol.

Who Might Benefit from Luteal Phase Ovarian Stimulation?

While LPOS offers several potential advantages, it may not be suitable for everyone undergoing IVF. Candidates who might benefit from LPOS include:

• Women with regular menstrual cycles and predictable ovulation
• Individuals with diminished ovarian reserve or poor ovarian response
• Patients who have experienced unsuccessful outcomes with traditional IVF protocols
• Patients who have experienced severe ovarian hyperstimulation.

It’s essential to consult with a fertility specialist to determine whether LPOS is the right approach for your unique circumstances.

Luteal Phase Ovarian Stimulation IVF Protocol represents a promising alternative to traditional IVF protocols, offering potential benefits such as minimized wait time and reduced ovarian suppression. LPOS has been shown in the research to effectively increase the number of mature eggs in women with a history of poor ovarian response and have a comparable response to traditional follicular phase protocols.  However, like any fertility treatment, it’s crucial to weigh the pros and cons and consult with a qualified fertility specialist to determine the most appropriate approach for your unique situation.