oshiroDr. Bryan Oshiro, Maternal Fetal Medicine Physician

Dr. Oshiro obtained his medical degree (MD) from Loma Linda University, where he also completed his residency in Obstetrics and Gynecology. He subsequently completed a fellowship at the University of Texas in Houston. Dr. Oshiro is board certified in Obstetrics and Gynecology and Maternal-Fetal Medicine. He has participated in numerous multi-center trials and has published numerous articles and book chapters in the areas of quality improvement, perinatal infectious diseases, and high-risk pregnancy conditions.

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ronaldDr. Ronald Johnson, Department of Gynecology and Obstetrics Chair

Ronald Johnson, MD, is a board-certified OB/GYN specialist who has worked with Riverside University Health System since 2017. He is a graduate of Loma Linda University School of Medicine, and completed his residency at Loma Linda University Medical Center. He has been involved in resident education for the past 31 years and is currently an Assistant Professor at Loma Linda University School of Medicine. His specialty is gynecologic surgery including minimally invasive approach and gynecologic ultrasound. He is working with Dr. Bryan Oshiro on a $6.38 million grant from First 5 Riverside as they aim to improve high-risk prenatal care in Riverside County through the the HeRCARe program.

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sarahDr. Sarah Smithson, Maternal Fetal Medicine Physician

Sarah Smithson, DO, MS, is the newest physician member of the MFM Department at RUHS. She obtained her medical degree at the University of New England College of Osteopathic Medicine in Biddeford, Maine followed by residency in Obstetrics and Gynecology at Monmouth Medical Center in Long Branch, New Jersey. During residency, she completed a master’s degree in Medical Education and Leadership from the University of New England College of Osteopathic Medicine. She moved to the west coast to complete a fellowship in Maternal Fetal Medicine at Cedars Sinai Medical Center in Los Angeles. Her research interests include hypertensive disorders of pregnancy and postpartum depression. She has conducted several research studies which have resulted in multiple recent publications. Clinical interests include prenatal ultrasound as well as resident education.

sabreenProgram Director: Sabreen White, MBA

Sabreen has a master’s degree in business and healthcare management along with 16 years of experience in public health and government programs. She is a seasoned project manager with a demonstrated history of budget management and preparation, grant writing, community and government collaboration, IRB/Research Coordination, program evaluation and development.




blankMaternal Fetal Medicine Physician: Dr. Janet Horenstein

Dr. Janet Horenstein is board certified in Obstetrics / Gynecology and Maternal Fetal Medicine.  She has been with RUHS since 2019. She completed her medical training at the Universidad Autonoma de Guadalajara. After she completed residency in Obstetrics and Gynecology at White Memorial Medical Center in Los Angeles, she completed fellowship in Maternal Fetal Medicine at LAC-USC. She remained on staff for a number of years teaching medical students, residents and fellows. Her interest is fetal evaluation and treatment. She had published many articles and has lectured nationally and internationally.  She has been involved in outreach teaching ultrasound to midwives in Ghana. When not working, she spends time with her animals and travels.