Several North American cities are considering the use of new contraceptive products to address rat infestations. This effort is commendable as it shows that cities are exploring alternative approaches to more established techniques that are known to cause harms, such as poisons that kill non-targeted wildlife.

Rat birth control products, packaged as sugary bait, reduce the number of offspring rats produce. Given that rats can have about five litters a year, with an average of four to eight pups in each litter, addressing reproduction is an attractive approach to reducing rat numbers. However, there are three important limitations to such a strategy.