Meet the Downtown Chicago Maternal-Fetal Medicine Team

Our team is made up of highly skilled, internationally recognized maternal-fetal specialists. These specialists are committed to providing outstanding, comprehensive care for patients with high-risk pregnancies.


Our physicians are full-time teaching faculty of Northwestern University Feinberg School of Medicine. They are also board-certified specialists in obstetrics and gynecology and maternal-fetal medicine.


Fellows are physicians who have completed their training in Obstetrics and Gynecology and are now obtaining additional specialized training in Maternal-Fetal Medicine.

  • Mariana Espinal, MD
  • Nkechinyelum (Kiki) Ogu, MD
  • Nigel Madden, MD

Advanced Practice Providers

Charlotte M. Niznik is an advanced practice registered nurse in the Division of Maternal-Fetal Medicine for the Northwestern Medicine Department of Obstetrics and Gynecology. She is a Certified Diabetes Educator. She specializes in women's health with a focus in diabetes and pregnancy management.

Ismene Potakis is a physician assistant (PA-C) in the Division of Maternal-Fetal Medicine (MFM) for Northwestern Medicine. She has been with the team since June 2021 and has been working in Obstetrics & Gynecology since 2013. Ismene is committed to her patients, wanting them to leave each visit feeling that they have been heard and that their needs are being addressed by the care team. Ismene is committed to working collaboratively with multi-disciplinary teams across the system towards achieving the ultimate goal of a healthy, thriving patient.


  • Amanda Criner, BSN, RN
  • Megan Heinlen, BSN, RN
  • Linda Jagielski, LPN
  • Karyn Lasin, BSN, RN
  • Emily Steveson, BSN, RNC-OB,
    Senior Practice Manager
  • Amber Sword, BSN, RNC-OB

Support Staff

  • Stephanie Balthazar
  • Linda Hernandez
  • Elizabeth Koch
  • Vicky Onifade
  • Liliana Serrano