But the fact is that, until very recently in history, almost all human societies have regarded pregnancy outside of marriage as highly morally reprehensible. There can be little doubt that this moral norm evolved to protect the community from having children with no means of support born into it.
Traditional agrarian societies controlled their birth rate by two taboos. Young people were not allowed to marry until they had land to farm, or a trade by which to support a family. Sexual intercourse outside of marriage was restricted by moral sanction. By these means the birth rate was tied to economic production and a rough balance kept.
As a moral code with a practical purpose, it must have worked, or it wouldn't have lasted so long or been so universal. Yes, it involved being judgmental, and stigmatising those who broke the code as immoral, but that was the whole idea. It was far kinder in the long run than the poverty and starvation that followed from more children being born than could be comfortably supported.
This ancient code only broke down within the last 40 years, under the influence of easy and effective contra-ception and a welfare state.
I am not suggesting for a moment that our society faces the same dangers from teenage pregnancy as would, say, a medieval subsistence village community, but the same underlying moral principles still apply. It is wrong to produce children that you cannot support yourself. As a society we do a disservice to young people if we do not express proper disapproval of behaviour that harms society.
For a young teenage girl to get pregnant is a wrong thing to do, and to hide that fact from her would be to lie to her.