Founder & Medical Director

Dr. Mark Leondires

Mark P. Leondires, MD is the Founder and Medical Director at Illume Fertility and Gay Parents To Be. He is board certified in both Obstetrics and Gynecology and Reproductive Endocrinology and Infertility.

Dr. Leondires currently serves as a member of RESOLVE's Physician Council, a member of ASRM's Diversity, Equity & Inclusion Task Force, and is on the board of The Nest Egg Foundation, which offers grants to fertility patients. He is also the past President of ASRM's LGBTQ Special Interest Group.

In addition, Dr. Leondires is co-author of Building Your Family: The Complete Guide to Donor Conception, the first all-inclusive guide covering both the medical and emotional aspects of becoming a parent through donor conception.

"From a young age, I always wanted to have a family myself. Having gone through my own family-building journey, I have a unique perspective and compassion for what my patients are going through."

Dr. Mark Leondires

Get to Know Dr. Leondires

For Dr. Leondires, practicing medicine offers an opportunity to solve problems and care for people, with each fertility patient presenting a unique puzzle to be solved.

This, combined with a wide range of interests and personal life events, is how Dr. Leondires was drawn into the field reproductive endocrinology and infertility.

In 2002, he founded Illume Fertility, growing the practice from the ground up and soon expanding from one location to five. His goal? To serve the local community and provide inclusive care for anyone hoping to build a family.

Educational Background

After his undergraduate years at Colby College, Dr. Leondires attended medical school at the University of Vermont in Burlington, VT. He went on to complete his residency in Obstetrics and Gynecology at Maine Medical Center in Portland, Maine.

As a resident, Dr. Leondires was exposed to a range of medical specialties. After initially feeling drawn to pediatrics, he worked with a reproductive endocrinologist and infertility specialist in his final week of residency and decided to become a fertility specialist.

Dr. Leondires continued his training with a fellowship in Reproductive Endocrinology and Infertility at the National Institutes of Health (NIH) in Bethesda, Maryland. After his reproductive endocrinology fellowship at the NIH, he served as the Director of Assisted Reproductive Technologies at the Combined Federal Program for Reproductive Endocrinology while on active duty in the U.S. ARMY.

"Whether it’s helping someone preserve their fertility, maximize their fertility potential, or guide them through the donor conception process, helping people on their pathway to parenthood is an incredible honor and privilege that energizes me every day."

Dr. Mark Leondires

More About Dr. Leondires

Another puzzle Dr. Leondires has worked diligently to solve is family building for the LGBTQ+ community. For him, this mission isn't just a professional one, but a life challenge that hits close to home. Alongside his husband, whom he married in 2009, Dr. Leondires is a dedicated father to two young sons via egg donation and surrogacy.

After navigating the process of becoming a parent, Dr. Leondires recognized the limited options available to the LGBTQ+ community. This led him to create and launch Gay Parents To Be, an educational resource hub supporting LGBTQ+ couples and individuals on their own family-building journeys. Dr. Leondires believes that anyone who wants to be a parent should have an opportunity to achieve that dream!

While his academic and professional career has led Dr. Leondires to spend his time in labs, hospitals and medical offices, he has not abandoned his love for biology and the outdoors. He spends much of his time at the beach, teaching his two young boys about the marine life of the Long Island Sound. When he isn't taking care of patients, he also enjoys being outdoors hiking, biking, and skiing.

patient testimonials

“Dr. Leondires is a very good communicator, he's approachable and always keen to answer questions. He's very knowledgeable about LGBTQ+ patients' specific needs and you feel supported in your desire to build a family without judgment. He went through it himself - he's a gay dad and I liked that.”

Intended Parent | Surrogacy Journey

“Dr. Leondires, your gift as a doctor is not just that you are good at what you do; you combine great professionalism with empathy and compassion for what your patients are experiencing. Your genuine happiness for us as we 'graduated' from Illume Fertility made it clear that you are truly in the right profession!"

E.S., Fairfield, CT

“Dr. L and his team are always efficient, kind and accommodating to my patient needs and my work schedule hours. His dedication and knowledge make me feel confident that I am in the best hands that I can be.”

L.O., New York, NY

“Dr. L, thank you for always hearing us out, for giving us guidance when we felt lost, for always providing hope when we feel on the edge of being hopeless, for reaching out on your day off, and for going the extra mile for your patients. It means the world to us.”

C.S., Weston, CT

Education & Honors

Colby College, BS
University of Vermont College of Medicine, MD
Maine Medical Center Residency Program, OB/GYN
National Institutes of Health, Fellowship in REI
Castle Connolly Top Doctor and Best Doctors in America

Considering donor conception?

Once shrouded in secrecy, the topic of donor conception has become much more mainstream, helping heterosexual couples dealing with infertility, LGBTQ+ couples, and single parents by choice expand their families.

In their new book Building Your Family: The Complete Guide to Donor Conception, Dr. Mark Leondires and Lisa Schuman, LCSW offer an all-inclusive guide to the medical, emotional, and genetic aspects of the process, covering everything from choosing a donor to raising donor-conceived children and beyond.

Both experts have decades of experience working closely with patients who have opted to use donated eggs and sperm, as well as their own personal stories of fertility treatment and non-genetic parenthood. Find your way forward with confidence and joy with the help of this comprehensive resource!

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Our team of nine board-certified reproductive endocrinologists are ready to help you create the family of your dreams. Take the first step by scheduling your consult today and learn how Illume Fertility can help you achieve your goals.

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