No one can say with certainty what's behind the halving of New Zealand's teen birth rate in eight years.
As we reported yesterday, new Statistics New Zealand data shows the teen birth rate has dropped each year since 2008 when it was 33 births per 1000 women aged 15 to 19.
Last year the rate dropped to 16 births per 1000 women in that age group.
Family First NZ national director Bob McCoskrie thinks he knows the reason - that the message to abstain from or postpone sexual involvement is getting through to teens.
He cited an Auckland University survey which found fewer students reported having sex in 2012 than in 2001 and 2007.
And he says evidence shows the drop in teen pregnancy rates was not down to contraception and the morning-after pill. In fact, he refers to a study that found access to emergency contraception increases the rates of sexually transmitted diseases, risk-taking and a false sense of security, while doing nothing to reduce the number of abortions.
These studies are no doubt legitimate and back up the Family First message of abstinence.
But I still find it hard to believe more teenagers than nine years ago are abstaining from or postponing sex. It seems more likely they have simply got smarter about contraception, as teens are getting smarter and more aware about many aspects of the world around them.
Encouraging teens to abstain, or to at least think very carefully before taking that step, is not a bad thing. It's a big step, one many young people take way too soon, before they are ready to deal with all the consequences - emotional, physical and social. But the reality is teenagers will go ahead and do what they do, regardless of what the grown-ups tell them.
So as well as preaching abstinence, we must continue to teach teenagers about contraception, including the emergency kind, as well as making sure they have access to it. That way we have all our bases covered.