Notes from Jacqueline Lichtenberg.  (Source:  Index card file, BIRTH CONTROL METHODS)

Jean:  Getting a husband and wife out of phase so she'd be infertile when he was horniest (assuming transfer triggers ovulation), and he'd be at turnover and probably impotent when She was interested.

April 20, 1977 --- This wouldn't be Satisfying to either party and thwarts deep instinctive drives and tendency for Sime~Gen couples to fall naturally into phase.  This might work for certain individuals.

Other methods:  Interruptus not favored by Simes (mutual attunement of nervous systems more dominant than in Ancients.)  Gens might not mind this method.  Condom and diaphram in various forms -- channel's sensitivity would make either method unpleasant or unendurable.  Abstention is out of the question for channels.  Tied tubes and hysterectomy only out-Territory on Gens.  Vasectomy -- for Gens, but WHY with low population.  Also, abortion and chemical means.

Basically comes down to matter of individual requirements, prejudices, tastes, religious convictions.  In an entire world, anything is possible.