I am a neonatologist interested in fetal growth retardation. Studies suggest that intrauterine growth retardation is associated with a higher risk of obesity, insulin resistance and adult-onset diabetes. My colleagues and I have developed an intrauterine growth retardation model that shows the development of insulin resistance and eventually diabetes. My goal is to elucidate the cellular and molecular mechanisms responsible for the development of diabetes.

In the lab, we are currently focusing on mitochondrial dysfunction in the b-cell. We are measuring mitochondrial function in pancreatic islets and the gene expression and activity of several enzymes that are key to energy production. We will soon determine whether our animal models develop hepatic insulin resistance. Also, in collaboration with Drs. Franz Matschinsky and Morris Birnbaum at the University of Pennsylvania, a variety of experimental techniques are used, including perfusion studies of isolated islets, measurements of insulin-stimulated glucose uptake and utilization using radiolabeled glucose analogs, in vivo euglycemic clamp and oral glucose tolerance studies, RT-PCR, differential display PCR, and Northern and Western Blot analyses.

Education and Training

Medical School

MD - University of Arizona, Tucson, AZ


Northwestern University Medical School, Chicago, IL
Children's Memorial Hospital, Chicago, IL


Pediatrics - University of Arizona Medical Center, Tucson, AZ


Cardiovascular Research Institute, University of California, San Francisco, CA

Board Certification

Neonatal-Perinatal Medicine

Titles and Academic Titles

Attending Neonatologist

Professor of Pediatrics, Perelman School of Medicine at the University of Pennsylvania

Departments and Services

Research Interests




Russell MW, Moldenhauer JS, Rychik J, Burnham NB, Zullo E, Parry SI, Simmons RA, Elovitz MA, Nicolson SC, Linn RL, Johnson MP, Yu S, Sampson MG, Hakonarson H, Gaynor JW. Damaging Variants in Proangiogenic Genes Impair Growth in Fetuses with Cardiac Defects. J Pediatr. 2019 Jun 18. pii: S0022-3476(19)30578-5. doi: 10.1016/j.jpeds.2019.05.013. [Epub ahead of print]


Xin F, Fischer E, Krapp C, Krizman EN, Lan Y, Mesaros C, Snyder NW, Bansal A, Robinson MB, Simmons RA, Bartolomei MS. Mice exposed to bisphenol A exhibit depressive-like behavior with neurotransmitter and neuroactive steroid dysfunction. Horm Behav. 2018 May 12. pii: S0018-506X(18)30023-0. doi: 10.1016/j.yhbeh.2018.05.010. [Epub ahead of print]

Jensen EA, Foglia EE, Dysart KC, Simmons RA, Aghai ZH, Cook A, Greenspan JS, DeMauro SB. Adverse effects of small for gestational age differ by gestational week among very preterm infants. Arch Dis Child Fetal Neonatal Ed. 2018 May 5. pii: fetalneonatal-2017-314171. doi: 10.1136/archdischild-2017-314171. [Epub ahead of print]

Alexander J, Teague AM, Chen J, Aston CE, Leung YK, Chernausek S, Simmons RA, Pinney SE. Offspring sex impacts DNA methylation and gene expression in placenta from women with diabetes during pregnancy. PLoS One. 2018 Feb 22;13(2):e0190698. doi: 10.1371/journal.pone.0190698. eCollection 2018.

Gaynor JW, Parry S, Moldenhauer JS, Simmons RA, Rychik J, Ittenbach RF, Russell WW, Zullo E, Ward JL, Nicolson SC, Spray TL, Johnson MP. The impact of the maternal-foetal environment on outcomes of surgery for congenital heart disease in neonates. Eur J Cardiothorac Surg. 2018 Feb 13. doi: 10.1093/ejcts/ezy015. [Epub ahead of print] PMID: 29447332 [PubMed - as supplied by publisher]

Stuart TJ, O'Neill K, Condon D, Sasson I, Sen P, Xia Y, Simmons RA. Diet-induced obesity alters the maternal metabolome and early placenta transcriptome and decreases placenta vascularity in the mouse. Biol Reprod. 2018 Jan 18. doi: 10.1093/biolre/ioy010. [Epub ahead of print] PMID: 29360948

Rashid CS, Lien YC, Bansal A, Jaeckle-Santos LJ, Li C, Won KJ, Simmons RA. Transcriptomic analysis reveals novel mechanisms mediating islet dysfunction in the intrauterine growth restricted (IUGR) rat. Endocrinology. 2018 Jan 4. doi: 10.1210/en.2017-00888. [Epub ahead of print] PMID: 29309562


Tran PV, Kennedy BC, Lien YC, Simmons RA, Georgieff MK. Fetal iron deficiency induces chromatin remodeling at the Bdnf locus in adult rat hippocampus. Am J Physiol Regul Integr Comp Physiol. 2014 Dec 17:ajpregu.00429.2014. doi: 10.1152/ajpregu.00429.2014. [Epub ahead of print]. Read the abstract.


Simmons RA: Preclampsia and prematurity as precursors to adolescent obesity. J Pediatr 162: 889-890, 2013.

Simmons RA: Programming of DNA methylation in type 2 diabetes. Diabetologia 56: 947-948, 2013. Invited commentary.


Pinney SE, Simmons R: Metabolic programming, epigenetics, and gestational diabetes mellitus. Curr Diab Rep 12: 67-74, 2012.

Simmons RA: Developmental Origins of Diabetes: The Role of Oxidative Stress. Best Pract Res Clin Endocrinol Metab 26: 701-708, 2012, NIHMS 375424.


Simmons RA: Abnormalities of Fetal Growth in Avery's Diseases of the Newborn. Avery's Diseases of the Newborn. SU Devaskar, CA Gleason (eds.). WB Saunders, Philadelphia, Page: 51-59, 2011.

Simmons RA: Cell glucose transport and glucose handling during fetal and neonatal development. Fetal and Neonatal Physiology Fourth Edition. R Poin, W Fox, S Abman (eds.). Elsevier Saunders, Philadelphia, Page: 560-568, 2011.

Simmons R: Epigenetics and maternal nutrition: nature v. nurture. Proc Nutri Soc 70: 73-81, 2011.

French HM, Simmons RA: Infant of a Diabetic Mother in Rudolph's Pediatrics, 22nd edition. Rudolph's Pediatrics. C Rudolph, G Lister, A Gershon, L First, A Rudolph (eds.). McGraw-Hill, New York, 2011.


Sen S, Simmons RA. Maternal Antioxidant Supplementation Prevents Adiposity in the Offspring of Western diet-fed Dams. Diabetes. Epub 2010 Sep 7.  Read the abstract.