I’ve been thinking about this over the weekend.
When I logged back on, I was amazed to see how the debate was still raging - albeit raging round in cirlces.
I’ve concluded that a lot of Catholics have placed themselves exactly where the secular media wants them to be. To use a pastoral metaphor, they are running round like a load of panicky sheep because someone has shouted “WOLF!” …even though there isn’t actually a wolf in the field!
The Pope has confimred that abortion is evil. That should need to explanation or justification. I hope we all agree that extinguishing an innocent life is wrong.
We know that the Zika virus can be sexually transmitted and we know that if it enters the body of a female who is pregnant, it can result in severe deformity.
We know that there are 2 ways to prevent this: abstinence and barrier-method contraceptives. I’m not including NFP here because not every woman has a regular cycle. For some women, the perimenopause can last 10 years or more, so although it is a wonderful tool for many couples, it has limited use for many more.
So, armed with this knowledge and mindful of a whole load of ‘unknowns’ about Zika and the lifespan and healthcare needs of a baby born with a deformed head, a married couple who are already expecting a child and choose to protect the life of their unborn child by using a method of contraceptive that acts as a barrier … are still at fault (because abstinence would be better) but the Pope has comapssion for them because their primary motive is the protection of their baby and because as fallible humans, we do sometimes slip up.

Anyone who remained cellibate until their wedding night and has never used contraceptives (other than for other medical reasons) feel free to disagree.
(PS - I did manage the above and I can tell you, being finally married aged 42, it nearly cost me my sanity!!!)
However, even though contraception is a sin…in these circumstances, where there is a genuine fear of something pretty horrific and a lot of unanswerd questions about the long term prognosis and effects, the Pope is saying that the sin of contracepting is not as great as the absolute evil of deliberately killing a foetus.