Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Dr. Margaret I Stewart, M.D.

Dermatology Physician in Portsmouth, NH · enumerated 2006.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1649375072

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Registry record

Entity type Individual (Type 1)

Name Dr. Margaret I Stewart

Credential M.D.

Sex Female

Practice address 155 Borthwick Ave, Suite 201 West, Portsmouth, NH, 03801

Phone (603) 433-9575

Fax (603) 430-0104

Enumeration date Sep 13, 2006

Last updated in NPPES Oct 18, 2017

Taxonomy & licenses

207N00000X Dermatology Physician Allopathic & Osteopathic Physicians · License 159113 (MA) Secondary

207N00000X Dermatology Physician Allopathic & Osteopathic Physicians · License 11839 (NH) Primary

MD · Doctor of Medicine: A physician who completed medical school (allopathic medicine), residency training, and state licensure. About the MD credential

Other identifiers

Identifier	Type	State	Issuer
J19743	Other	MA	BCBS MASSACHUSETTS
P00366953	Other	NH	RAILROAD MEDICARE
403898	Other	MA	TUFTS
01Y004640NH01	Other	NH	ANTHEM NEW HAMPSHIRE
2457634	Other	MA	AETNA
022071	Other	ME	ANTHEM MAINE
401347	Other	MA	HARVARD
P00126157	Other	MA	RAILROAD MEDICARE

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

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Frequently asked questions

What is the NPI number for Margaret Stewart?

The National Provider Identifier (NPI) for Margaret Stewart is 1649375072, a Type 1 (individual) record in the CMS NPPES registry.

Where does Margaret Stewart practice?

The practice location on file with NPPES is in Portsmouth, NH. Providers can have multiple locations; NPPES lists the primary practice address.

Other providers at this practice address

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2017-10-18.