It was presented as in-universe, medical rather than social, fact in prior editions. Omniscient, word of God, impartial, truth (not in-character chatter).
In SR1? Yeah, more or less. I quote, "Ork mothers usually bear four children, but litters of six or eight are not uncommon." I thought it had been presente as something Paterson put out, but maybe not. In any case, "litter" is probably a bad word, and Tom and co. certainly didn't think about the population explosion, or of mentioning higher infant mortality rates amongst orks.
Of course, according to the information on the same page, goblinization would appear to happen more often than some in-world would want to make it seem, since 95% of the apparently human children born to orks will goblinize at puberty.
I really wish there was some graceful way of dealing with this, but there really isn't.
