FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * NIERENBERG INVESTMENT MANAGEMENT CO   2. Issuer Name and Ticker or Trading Symbol NATUS MEDICAL INC [BABY] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 19605 NE 8TH STREET 3. Date of Earliest Transaction (Month/Day/Year) 06/30/2006 (Street) CAMAS, WA 98607 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 06/30/2006   J(1)(3)   132,161 D (1) (3) 0 I By The D3 Children's Fund, L.P. Common Stock 06/30/2006   J(1)(3)   551,940 D (1) (3) 0 I By The D3 Family Retirement Fund, L.P. Common Stock 06/30/2006   J(1)(3)   1,329,376 D (1) (3) 357,049 I By The D3 Family Fund, L.P, Common Stock 06/30/2006   J(2)(3)   332,522 A (2) (3) 689,571 I By The D3 Family Fund, L.P. Common Stock 06/30/2006   J(2)(3)   1,680,952 A (2) (3) 1,993,185 I By The D3 Family Bulldog Fund, L.P. Common Stock               826,158 I By The DIII Offshore Fund, L.P.

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
NIERENBERG INVESTMENT MANAGEMENT CO 19605 NE 8TH STREET CAMAS, WA 98607		X
DENVER CARA 19605 NE 8TH STREET CAMAS, WA 98607		X
D3 Family Bulldog Fund LP 19605 NE 8TH STREET CAMAS, WA 98607		X
HOOPER HENRY E 19605 NE 8TH STREET CAMAS, WA 98607		X
Nierenberg Investment Management Offshore Inc 19605 NE 8TH STREET CAMAS, WA 98607		X
NIERENBERG DAVID 19605 SE 8TH STREET CAMAS, WA 98607		X

Signatures

David Nierenberg, President, Nierenberg Investment Management Company, Inc. (NIMCO)		07/05/2006
**Signature of Reporting Person		Date
David Nierenberg		07/05/2006
**Signature of Reporting Person		Date
Henry Hooper		07/05/2006
**Signature of Reporting Person		Date
Cara Denver		07/05/2006
**Signature of Reporting Person		Date
David Nierenberg, President, NIMCO, General Partner of The D3 Family Bulldog Fund, L.P.		07/05/2006
**Signature of Reporting Person		Date
David Nierenberg, President, Nierenberg Investment Management Offshore Inc. (NIMO)		07/05/2006
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Pro rata distribution of issuer shares owned by limited partnership to its general and limited partners as part of consolidation of funds within fund family. These shares have previously been included in statements filed by David Nierenberg, President of Nierenberg Investment Management Company, Inc., the general partner of the limited partnership and by Nierenberg Investment Management Company, Inc.
(2)	Pro rata receipt of issuer shares by limited partnership from its general and limited partners as part of consolidation of funds within fund family. These shares have previously been included in statements filed by David Nierenberg, President of Nierenberg Investment Management Company, Inc., the general partner of the limited partnership and by Nierenberg Investment Management Company, Inc.
(3)	Four of the reporting persons, D3 Childrens Fund, LP (CIK 0001226845), D3 Family Fund, LP (CIK 0001282685), DIII Offshore Fund, LP (CIK 0001282684) and D3 Family Retirement Fund, LP (CIK 0001226843), would be reported in this filing if we had the appropriate Edgar codes from the SEC. We made a formal request for the codes from the SEC. Since we do not have all of the appropriate codes at the time of this filing, we will file an amended Form 4 when we receive the correct Edgar codes.
Remarks: As officers of Nierenberg Investment Management Company, Inc., the sole general partner of each of the limited partnerships, David Nierenberg, Henry Hooper and Cara Denver may be deemed to share voting and investment power over the issuer shares owned by the limited partnerships. Each officer is allocated by agreement a portion of the general partner's carried interest in each of the limited partnerships, and each officer beneficially owns limited partnerships interest in The D3 Family Fund, L.P. Each of the reporting persons disclaims beneficial ownership except to the extent of the reporting person's pecuniary interest.

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