Notice please that it more often happens,
 that the artist  place the mother to the left side of the picture than to the right..
It is a psychological effect , the world is to the left and home is to the right side. 
When the mother sits in the left side she protects .
 If she sits in the right she let the child have a certain freedom.
I speculated if  another  reason could be that we mothers carry the baby on our left side,
 so we have the right arm free to do things with.
So perhaps the few painting with mothers in the left side of the picture
 actually show left handed mothers?
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| Hans Thuar German Artist 1887-1945
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| J. Mainberger after Von Kaulbach Found in German Auctionsite
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| Marie Danforth Page "Her littlest one"
 American painter 1869-1940
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| .jpg) | 
| Garibaldi Melcher | 
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| Rosalie Lorrain Gill American Painter
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| Tamara de Lempicka | 
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| Gustave Klimt | 
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| Stanislaw Wyspianski Portrait of Salomea Hankiewiczsowa
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| Poul S Nielsen Mother and child
 Danish Artist
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| Virgin Mary | 
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| Max Corneille | 
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| Mary Cassatt "Sleepy"
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| Evert Lundquist Mother and child
 Swedish Artist
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| Julius Garibaldi Melcher | 
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| Edvard Manet | 
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| Mary Cassatt | 
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| Carlton Alfred Smith | 
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| Norbert Goeneutte | 
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| Giovanni Segantini | 
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| Giovanni Segantini | 
A remarkable frame.It looks like Leonardo da Vinci designed it.
| -gamle-sofi+from+Polarbears+tale.jpg) | 
| Carl Wilhelmsohn | 
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| Mary Cassatt | 
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| Jacob van Doorth Portrait of Anna Catharina Brandenburg
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| Joseph Raphael "In the Garden"
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| Andrea del Brescianino |