The report says that the number plummeted from 74.9% to 58.5% in four years.
57.1% of urban and 59.4% of rural couples had rooms of their own in 2012.
During that period, the birth rate fell from 22.2 per 1000 to 20.6 per 1000.
This is consistent with the overall decline of population growth in the last century.
Couples in urban Maharashtra had the least space to themselves: only 51.1% of households have a room to themselves.
Between 2008 and 2011, the birth rate in urban parts of the state dropped from 17.2 per 1000 to 15.8 per 1000.
The decreasing number of separate rooms for couples, especially in urban areas, points to overcrowding, perhaps due to rising real-estate prices.
"Overcrowding has various adverse effects to leading a healthy and undisturbed life and hence is considered as an important problem to be addressed by urban planning," the survey said.