French advice on nonfrank breech birth: apply counter-pressure to the emerging foot/feet

I'm wading through obstetrical literature of the 1980s & 1990s to discover information relating to type of breech presentation and the associated risks/outcomes.

In a 1981 article by J. Dubois, Some present aspects of the problems of breech presentation and delivery, he gives advice on attending nonfrank vaginal breech births. From p. 489:

#6. The nonfrank breech. We have already seen how it can pose some particular problems. If one decides to attempt a vaginal breech birth, one should take, at a minimum, 3 precautions: keep the membranes intact until full dilation; be on guard for cord presentation or cord prolapse; at the moment of expulsion, slow the emergence of the foot/feet for at least a little while by pressing one hand against the vulva.

By implication, the last precaution refers specifically to breeches emerging feet-first, aka footling breech, and perhaps also to a complete breech with the foot/feet slightly in front of the buttocks. The French obstetrical nomenclature doesn't generally have a specific term for footling, just nonfrank (siège complet) and frank (siège décomplété).

The last part struck me, as it echoes a technique proposed by Russian obstetrician Tsovianov, the Tsovianov II. This maneuver converts a footling breech into a complete breech.

Antonín Doležal. Porodnické operace. 2007

Dubois' recommendations do not mention the goal of converting leg position, but that could be a side result of counter-pressure against the feet. This technique could provide additional time for the cervix to dilate, if not already fully dilated.