Helvig OfSchleswig

Helvig of Schleswig (da. Helvig af Slesvig), also erroneously Hedwig of Schleswig; died 1374, was a Danish Queen consort, spouse of King Valdemar IV of Denmark. She was the mother of Queen Margaret I of Denmark, Norway and Sweden.

Helvig was the daughter of Eric II, Duke of Schleswig and sister of Valdemar V, Duke of Schleswig, who had contended the Danish throne with her Christopher II of Denmark. She married Valdemar IV in 1340 at Sønderborg Castle. She brought with her a great dowry, which helped Valdemar in his politics. Valdemar suspected Helvig of adultery, and she was given her own castle and resided there with her own court, separated from him. In 1355 Queen Helvig, became a lay sister at Esrum Abbey after being supplanted by King Valdemar's mistress, Tove. The queen was buried in the abbey church, which brought royal gifts of property for the abbey.

Children
Helvig and Valdemar IV had at least six children;

Christopher, Duke of Lolland (1344-1363)
Margaret (1345-1350); betrothed to Henry III, Duke of Mecklenburg-Schwerin
Ingeborg (1347-1370); married Henry III, Duke of Mecklenburg-Schwerin, and was the maternal grandmother of King Eric VII of Denmark
Catherine (1349); died young
Valdemar (1350); died young
Margaret I of Denmark (1353-1412) (Source - http://en.wikipedia.org/wiki/Helvig_of_Schleswig)