Ampt FH, Lim MSC, Agius PA, et al. - In view of the high risks of unintended pregnancy among female sex workers in low-income and middle-income countries, researchers developed a 12-month, multifaceted short messaging service intervention (WHISPER) for female sex workers in Kenya who are at high risks of unintended pregnancy, to improve their knowledge and behaviours concerning contraceptives. Researchers performed a two-arm, cluster-randomized controlled trial examining the effectiveness of the intervention in lowering the incidence of unintended pregnancy among sex workers in Kenya compared with an equal-attention control group receiving nutrition-focused messages (SHOUT). Among 1,728 individuals approached for participation, 1,155 were eligible for full screening, 1,035 were screened, and 882 were eligible, enrolled, and randomly assigned (451 participants from 47 venues in the intervention group; 431 participants from 46 venues in the control group). Outcomes revealed no measurable effect of the intervention on unintended pregnancy incidence, hence suggesting insufficient effect of mobile health interventions, even when acceptable and rigorously designed, on behavior among female sex workers to change pregnancy incidence when used in isolation.