X0303 4 2010-03-05 1 0000878526 NATUS MEDICAL INC BABY 0001282683 Nierenberg Investment Management Company, Inc. 19605 NE 8TH STREET CAMAS WA 98607 0 0 1 0 0001282685 D3 Family Fund, LP 19605 NE 8TH STREET CAMAS WA 98607 0 0 1 0 0001365745 D3 Family Bulldog Fund, LP 19605 NE 8TH STREET CAMAS WA 98607 0 0 1 0 0001282684 DIII Offshore Fund, LP 19605 NE 8TH STREET CAMAS WA 98607 0 0 1 0 0001365764 Nierenberg Investment Management Offshore Inc. 19605 NE 8TH STREET CAMAS WA 98607 0 0 1 0 0001040899 Nierenberg David 19605 NE 8TH STREET CAMAS WA 98607 0 0 1 0 Common Stock 2010-03-05 4 S 0 9852 14.4 D 477083 I By The D3 Family Fund, LP Common Stock 2010-03-05 4 S 0 39000 14.40 D 1918859 I By The D3 Family Bulldog Fund, LP Common Stock 2010-03-08 4 S 0 23000 14.4 D 454083 I By The D3 Family Fund, LP Common Stock 2010-03-08 4 S 0 90000 14.40 D 1828859 I By The D3 Family Bulldog Fund, LP Common Stock 2010-03-08 4 S 0 16718 14.4 D 429338 I By The DIII Offshore Fund, LP Common Stock 2010-03-09 4 S 0 6200 14.46 D 447883 I By The D3 Family Fund, LP Common Stock 2010-03-09 4 S 0 26404 14.46 D 1802455 I By The D3 Family Bulldog Fund, LP Common Stock 2010-03-09 4 S 0 6600 14.46 D 422738 I By The DIII Offshore Fund, LP Common Stock 129931 I By The D3 Family Canadian Fund, LP Each of the reporting persons disclaims beneficial ownership of these securities except to the extent of the reporting person's pecuniary interest therein. David Nierenberg, President, Nierenberg Investment Management Company, Inc. (NIMCO) 2010-03-09 David Nierenberg, President, NIMCO, General Partner of The D3 Family Fund, LP 2010-03-09 David Nierenberg, President, NIMCO, General Partner of The D3 Family Bulldog Fund, LP 2010-03-09 David Nierenberg 2010-03-09 David Nierenberg, President, Nierenberg Investment Management Offshore, Inc. (NIMO) 2010-03-09 David Nierenberg, President, NIMO, General Partner of The DIII Offshore Fund, LP 2010-03-09