Our Pediatric Experts

Dr. Sarah Kay Herrera, MD, FAAP, is a pediatrician at Southern Orange County Pediatric Associates in Ladera Ranch, California, specializing in the health and well-being of children. Practicing since 2015 and at SOCPA since 2022, she provides comprehensive, family-centered care for infants, children and teens.

Dr. Herrera also visits newborns at Hoag Hospital Irvine, Saddleback Medical Center, and Rady Children’s (formerly CHOC) at Mission Hospital.

She is passionate about treating sick kids and sharing with families the pattern of an illness and red flags to monitor. As a member of the Rady Children’s Health Primary Care Network, she is part of a nationally recognized pediatric health system to deliver coordinated care and streamline access to specialty care and additional services when necessary. She is affiliated with the American Academy of Pediatrics.

The foundation of pediatrics is preventive medicine. Dr. Herrera’s primary goal is to partner with parents by teaching them about vaccines, development milestones, nutrition, emotional well-being, and safety.

“I count it such an honor to equip parents with the tools to allow their little to grow and flourish.”

She has firsthand experience being a nervous parent of a 33 weeker preemie a few years ago, and she is forever grateful to CHOC (now Rady Children’s) NICU.

Dr. Roia Katebian, MD, FAAP, is a double board-certified pediatrician and neonatologist at SOCPA in Ladera Ranch, specializing in the health and well-being of children. Practicing at SOCPA since 2026, she provides comprehensive, family-centered care for infants, children and teens. Dr. Katebian has continued to work per diem as a neonatologist throughout Southern California since 2021.

Dr. Katebian is particularly passionate about preventative pediatric care, breastfeeding education, and building lasting connections with families to support children through every stage of development. As a part of the Rady Children's Health Primary Care Network, she is a part of a nationally recognized pediatric health system to deliver coordinated care and streamline access to specialty care and additional services when necessary.

Dr. Katebian is affiliated with the American Academy of Pediatrics and participates in ongoing research focused on improving outcomes for children.

“My philosophy of care centers on building strong, trusting relationships with families and creating a supportive environment where children can thrive. The most rewarding part of being a pediatrician is watching my patients grow from newborns into individuals with their own personalities, interests, and dreams.”

Dr. Kenson Lo, MD, MPH, FAAP, is a board-certified pediatrician at Southern Orange County Pediatric Associates in Rancho Santa Margarita, California, specializing in the health and well-being of children. Practicing at SOCPA since 2013, he provides comprehensive, family-centered care for infants, children and teens. As a member of the Rady Children’s Health Primary Care Network, he is part of a nationally recognized pediatric health system to deliver coordinated care and streamline access to specialty care and additional services when necessary.

Dr. Katherine Nielsen, MD, is a board-certified pediatrician at SOCPA Rancho Santa Margarita, specializing in the health and well-being of children. Practicing in Pediatrics since 2016, she provides comprehensive, family-centered care for infants, children and teens. Dr. Nielsen also visits newborns at Mission/CHOC at Mission Hospital, Hoag Hospital Irvine, and Saddleback Hospital.

Dr. Nielsen is particularly passionate about adolescent mental health, completing the UCI School of Medicine Primary Care Psychiatry Fellowship in 2024. As a member of the Rady Children's Health Primary Care Network, she is part of a nationally recognized pediatric health system to deliver coordinated care and streamline access to specialty care and additional services when necessary.

Dr. Nielsen is a Fellow of the American Academy of Pediatrics and is currently completing her Master of Public Health degree with a focus on epidemiology, immunizations, and preventive health. Her research interests include vaccine education and immunization outcomes, as well as e-bike safety and injury prevention, reflecting her commitment to improving long-term health outcomes for children and adolescents.

"I believe healthy, happy kids are our future, and that prevention and compassionate care make all the difference."

Dr. James Su, MD, is a board-certified pediatrician at Southern Orange County Pediatric Associates specializing in health and well-being of children of all ages. Practicing since 2023, he provides comprehensive, family centered care for family with a collaborative approach. He also visits newborns at Hoag Irvine, Memorial Care Saddleback, and Providence Mission Viejo Hospitals.

Dr. Su is particularly passionate about early developmental delays in pediatrics. He works closely with the Thompson Autism and Neurodevelopment Center to provide autism diagnosis in the primary care pediatric setting for his patients. He is also passionate about travel medicine and sports injuries in pediatrics.

As a member of the Rady Children’s Health Primary Care Network, Dr. Su is part of a nationally recognized pediatric health system to deliver coordinated care and streamline access to specialty care and additional services when necessary. He is a member of the American Academy of Pediatrics.

Outside the office, Dr. Su can be found being active with his wife, Ashley, who is an anesthesiologist and dog, Hana, a Belgian Malinois/German Shepherd rescue. Dr. Su enjoys playing sports. He is an avid basketball player and likes to find time to work out and run with Hana. 

“Pediatric medicine is a collaborative effort between the patient, parents, and the pediatrician.”

Dr. Meena Tanwar-Ahuja, MD, PhD, is a board-certified pediatrician at Southern Orange County Pediatric Associates in Rancho Santa Margarita, Lake Forest, and Irvine, California, specializing in the health and well-being of children. Practicing at SOCPA since 2025, she provides comprehensive, family-centered care for infants, children and teens. Dr. Tanwar-Ahuja is particularly passionate about preventative medicine, building connections and trust with families, and caring for children through both illness and wellness. As a member of the Rady Children’s Health Primary Care Network, she is part of a nationally recognized pediatric health system to deliver coordinated care and streamline access to specialty care and additional services when necessary. Dr. Tanwar-Ahuja is a fellow of the American Academy of Pediatrics and holds a Ph.D. in Cancer Biology, reflecting her deep commitment to evidence-based medicine. She speaks Hindi and medical Spanish. A resident of South Orange County, she is a proud mother of four and has a passion for caring her children in her community. Outside the office, she enjoys both performing and teaching Indian dance, reading, exercising, and watching football with her family.