University Hospitals Pioneers Hormonal Environment Research to Better Understand IVF Outcomes

UH Innovations in Obstetrics & Gynecology | Fall 2021

In-vitro fertilization (IVF) has made major strides since its introduction in clinical practice, but it is still a relatively young field with many unanswered questions.

Rachel Weinerman, MD

“It's very important, as we acknowledge our success, to also acknowledge that there's a lot that we are still learning in the field of reproductive medicine about ideal environments for embryo transfer,” says Rachel Weinerman, MD, in the Division of Reproductive Endocrinology and Infertility at University Hospitals, where she also severs as Program Director for the Reproductive Endocrinology and Infertility Fellowship.

Dr. Weinerman is leading a research team at UH and the School of Medicine that is examining how the hormonal environment affects neonatal outcomes in babies born following IVF and other assisted reproductive technology procedures.

Babies born following IVF tend to have lower birth weights, and women carrying IVF babies have higher rates of preterm delivery and preeclampsia. “The basic underlying question that we’re trying to answer in our lab is, why are babies that are born following IVF different than babies that are born following natural conception?” Dr. Weinerman says.

She and her team are also examining how outcomes differ between different types of assisted reproductive technology. Neonatal outcomes are notably different following fresh IVF transfer than in frozen embryo transfers. If embryos are frozen and transferred a month later instead of immediately after egg retrieval, babies tend to have higher birth weights and longer gestational lengths. Dr Weinerman asks, “Why do we see differences in those birth outcomes, both overall in babies born following IVF and then also specifically in fresh compared to frozen IVF cycles?”

The research team is endeavoring to answer these questions in the research lab, beginning with mouse models. “We have now been able to recreate a model in the mouse of smaller birth weights in fresh compared to frozen embryo transfers,” Dr. Weinerman says. She and her team can transfer mouse embryos into a mouse uterus that has been subjected to the same hormones used in fresh IVF cycles. They found, similar to IVF in humans, that mouse pups are born smaller when the embryos are transferred into a hormonally stimulated environment.

In the research lab, Dr. Weinerman and her team are studying different hormonal environments in the mouse to understand how these environments cause growth changes in the mouse pups. “During the very crucial period of embryonic implantation, we have identified markers of blood vessel development and also markers of immune response in the mouse uterus that appear to be different in these hormonal environments. That may be responsible for these growth differences that we see in IVF,” she says.

The results of this research may translate into real-world care, helping physicians to better understand IVF and help mothers and their babies. Research like this is already changing the clinical practice of IVF.

“In the six years that I've been doing this research, there have been significant changes in the way that we practice IVF because of the recognition of the impact of the hormonal environment,” Dr. Weinerman says. “UH has a dedicated reproductive biology lab within UH MacDonald Women’s Hospital that really has been a wonderful place to conduct this innovative research.”

Dr. Weinerman and her team will continue to conduct research in this area to further drive innovation in the way IVF is delivered to patients. They are continuing to focus their research on the mechanisms behind the difference in the hormonal environment following hormonal stimulation, and they are actively studying the impact of freezing and frozen transfers on embryos. 

“We want to make sure that we have the best possible understanding of how embryos implant and grow so that we can improve outcomes for our patients and their babies,” she says.

If you are interested in learning more about the research being conducted at University Hospitals, contact Dr. Weinerman at Rachel.Weinerman@uhhospitals.org.

Contributing Expert:
Rachel Weinerman, MD
Physician, Division of Reproductive Endocrinology and Infertility
University Hospitals Fertility Center
Program Director, Reproductive Endocrinology and Infertility Fellowship
University Hospitals Cleveland Medical Center
Assistant Professor, Department of Reproductive Biology
Case Western Reserve University School of Medicine