What is a normal progesterone level 3 weeks post Frozen Embryo Transfer (FET) of a day 5 blastocyst?

Normal Progesterone Levels 3 Weeks Post FET of Day 5 Blastocyst

For optimal pregnancy outcomes after a frozen embryo transfer (FET) of a day 5 blastocyst, serum progesterone levels should be maintained between 10-32.5 ng/ml at 3 weeks post-transfer. This range is associated with the highest ongoing pregnancy rates based on current evidence.

Progesterone Monitoring After FET

Optimal Progesterone Levels

• Studies show that serum progesterone levels below 10 ng/ml on the day of embryo transfer are associated with lower ongoing pregnancy rates 1
• Conversely, levels above 32.5 ng/ml are associated with reduced live birth rates 2
• A minimum threshold of 9.8 ng/ml has been identified as significantly associated with live birth rates in single blastocyst transfers 3
• Another study found that a progesterone level of 20.6 ng/ml on the day of transfer was optimal for predicting ongoing pregnancy rates 4

Timing of Progesterone Support

• According to guidelines, luteal support should continue for 3-4 weeks after pregnancy confirmation (approximately 4 weeks after transfer) in artificial cycles 5
• In programmed cycles, both estrogen and progesterone should be maintained at original doses for 3-4 weeks after pregnancy confirmation 5
• Once pregnancy is confirmed, gradual reduction of hormonal support over 2 weeks is recommended 5, 6

Factors Affecting Progesterone Levels

Individual Variability

• Research shows that serum progesterone levels are generally reproducible in more than 80% of patients between consecutive FET cycles 3
• This suggests that a patient's progesterone response to supplementation is relatively consistent

Type of Cycle

• In artificial cycles (programmed FET), continued supplementation of both estradiol and progesterone is necessary as there is no corpus luteum 5
• In modified natural cycles, luteal support typically continues for only 1-3 weeks after pregnancy confirmation as the corpus luteum provides some endogenous hormone production 5

Management of Suboptimal Progesterone Levels

Low Progesterone Levels

• If serum progesterone is found to be below 10 ng/ml, rescue progesterone supplementation may be beneficial 1
• Adding subcutaneous progesterone (25 mg) has been shown to restore adequate progesterone levels in 83% of patients with initially low levels 1
• 90% of pregnancies in patients with initially low progesterone occurred in those who achieved adequate levels with rescue supplementation 1

High Progesterone Levels

• Levels above 32.5 ng/ml are associated with lower live birth rates 2
• Monitoring and potentially adjusting progesterone dosage may be necessary to avoid excessive levels

Clinical Implications

Monitoring Recommendations

• Measuring serum progesterone levels at 3 weeks post-FET provides valuable information about the adequacy of luteal support
• This timing coincides with pregnancy confirmation, allowing for adjustment of progesterone supplementation if needed

Pitfalls to Avoid

• Relying solely on symptoms to assess progesterone adequacy is unreliable as progesterone supplementation can cause symptoms that mimic early pregnancy 5
• Not all women with successful pregnancies report symptoms during early stages 5
• Failing to monitor progesterone levels may miss opportunities for intervention in cases of suboptimal levels

In conclusion, monitoring serum progesterone levels at 3 weeks post-FET of a day 5 blastocyst is clinically valuable, with optimal levels falling between 10-32.5 ng/ml. Levels outside this range may warrant adjustment of progesterone supplementation to maximize the chances of ongoing pregnancy and live birth.