As more families begin planning for parenthood earlier, surrogacy in Mexico has become an important option for many people pursuing their dream of having a child. Among the many factors that influence fertility, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are two of the most important hormones physicians evaluate when assessing ovarian function.
What Do LH and FSH Do?
LH and FSH are both produced by the pituitary gland and work together to regulate follicle development and ovulation.
FSH primarily stimulates follicle growth, allowing eggs to mature gradually. During the early stage of the menstrual cycle, FSH promotes the development of multiple antral follicles, while the follicle with the greatest developmental potential continues maturing in preparation for ovulation.
LH mainly participates in the ovulation process. Once a follicle reaches maturity, LH rises sharply, triggering the release of the mature egg. At the same time, LH supports the formation of the corpus luteum, providing hormonal support during the early stage of embryo implantation.
These two hormones work together to maintain a healthy ovulatory cycle.
Why Is the LH-to-FSH Ratio Important?
In addition to evaluating LH and FSH individually, physicians also pay close attention to the ratio between the two hormones.
For example, in some women with polycystic ovary syndrome (PCOS), LH remains consistently elevated while FSH stays relatively normal or low. As a result, follicles may begin developing but fail to mature and ovulate properly.
On the other hand, persistently elevated FSH levels may indicate diminished ovarian reserve. As ovarian reserve declines with age, the pituitary gland releases more FSH in an attempt to stimulate the remaining follicles. Therefore, an elevated baseline FSH level often suggests that ovarian function has begun to decrease.
Before ovarian stimulation begins, physicians use LH, FSH, and other hormone test results to develop an individualized stimulation protocol rather than applying the same medication regimen to every patient. This personalized approach helps improve the number of mature eggs retrieved while reducing the risk of ovarian hyperstimulation.
After egg retrieval, fertilized eggs are typically cultured to the blastocyst stage, followed by IVF-PGT. Embryo genetic testing helps identify embryos with stronger developmental potential, improves overall pregnancy efficiency, and reduces the risk of miscarriage caused by chromosomal abnormalities. This has become one of the major advantages of modern assisted reproductive technology and continues to play an increasingly important role in clinical practice.
For families planning to build their family through surrogacy in Mexico, understanding the roles of LH, FSH, and the entire reproductive endocrine system can provide a clearer understanding of the treatment process and help them make more informed decisions throughout their fertility journey.
Located in the heart of Mexico City, Power Fertility Clinic is a fully licensed fertility center operated by a U.S. reproductive medicine organization and situated just 500 meters from the U.S. Embassy. The clinic operates in compliance with U.S. FDA standards. Power IVF provides comprehensive fertility services, including egg donation, sperm donation, third-party reproduction, as well as complete U.S. egg freezing and IVF programs. Equipped with advanced laboratory technology and an experienced medical team, the clinic specializes in IVF-PGT (PGT-A) to help families improve their chances of a healthy pregnancy. Mexican law permits gender selection and the importation of cryopreserved reproductive tissue—including sperm, eggs, and embryos—and these services are available to everyone, including single individuals and LGBTQ families. Power IVF is fully licensed to receive cryopreserved reproductive samples from overseas, providing secure and efficient support for your fertility journey.
