In Spaeth's clinic there was a viable infant at six and a half months weighing 900 grams.

Spaeth says that he has known a child of six months to surpass in eventual development its brothers born at full term.
In some cases there seems to be a peculiarity in women which manifests itself by regular premature births.

La Motte, van Swieten, and Fordere mention females who always brought forth their conceptions at the seventh month.
The incubator seems destined to be the future means of preserving these premature births.

Several successful cases have been noticed, and by means of an incubator Tarnier succeeded in raising infants which at the age of six months were above the average.

A full description of the incubator may be found.