The woman in this painting is said to be Maris's wife Catharina Hendrika Horn, whom he married in 1867. Their first child was born in April 1868 (and died in March 1869). This work was painted when Maris was living in Paris. The woman's right breast was originally uncovered and was painted over later, probably not by Maris. A pencil study for the picture, squared for transfer, was in the possession of the Maris family in about 1908. (http://www.nationalgallery.org.uk/paintings/jacob-maris-a-young-woman-nursing-a-baby)