I've lately been looking into this, and I wonder what people here think. Seems like a low hanging fruit for successful altruistic people (possibly with other traits as well, such as being healthy). Both for the direct impact of creating a... better child than (than the counterfactual one), and also for the indirect impact of normalizing the practice.
EtA: If you want to answer anonymously, you can write to me here: http://admonymous.co/mati_roy. Please also mention in your message whether you want me to publish your answer here.