Sixteen RCTs were included in the review; however two of the abstinence-plus studies used the same data set. The total number of included participants was 29,599.
Abstinence-only programmes (3 studies).
Two studies reported no significant change in the frequency of intercourse or number of partners. One of these also reported no significant change in age of initiation, contraceptive use or pregnancy rate. The third reported an increase in the age at which sexual behaviour was initiated.
Abstinence-plus programmes (12 studies).
Of the 8 studies reporting the age of initiation, five reported no significant change, two reported a significant increase in the age of initiation of sexual behaviour (one in boys only and the other in girls only), and one reported a significant decrease in the age of initiation.
Eight studies reported the frequency of intercourse, of which three reported no significant change, four a significant decrease in frequency and one a significant increase in frequency. None of the 5 studies reporting the number of partners reported a significant change with abstinence-plus programmes.
Of 5 studies reporting knowledge about contraception, four reported significant increases in knowledge (one in females only and one in males only), and one no significant change. Six of the 9 studies reporting contraceptive use reported an increase with abstinence-plus programmes, and a seventh an increase in males and a decrease in females. One study reported a significant decrease in females only, whilst another found no significant change in contraceptive use. Four of the 5 studies reporting condom use reported no significant change, while one reported an increased use of condoms. Only one study reported pregnancy rates, with no significant effect of abstinence-plus programmes.
Abstinence-only compared with abstinence-plus programmes (1 study).
This study reported no significant difference between the interventions in relation to age of initiation of sexual behaviour or frequency of intercourse. Those receiving abstinence-plus programmes had a significant increase in contraceptive knowledge and use and condom use.