We classified peer exposures using a framework to distinguish different mechanisms by which influence might occur.
We found 30 studies and retained 11 that met quality criteria.
The discovery was made by inflating the penises of dead dolphins to simulate their strange sex lives.
Pictured is the shape correspondence of male and female genitalia.
Female dolphins have evolved complicated vaginas that protect them from being fertilised by unwanted partners, new research suggests.
Adolescents in sub-Saharan Africa are highly vulnerable to HIV, other sexually transmitted infections (STIs) and unintended pregnancies.All studies found evidence for an association between peers and sexual behaviour for at least one peer exposure/outcome/sub-group association.Of all 37 outcome/exposure/sub-group associations tested, there was evidence for 19 (51%).There has not yet been a systematic review on the topic in sub-Saharan Africa.We searched 4 databases to find studies set in sub-Saharan Africa that included an adjusted analysis of the association between at least one peer exposure and a sexual behaviour outcome among a sample where at least 50% of the study participants were aged between 13 and 20 years.