Okay, okay! I asked him!
So, I asked DH about the Greek - and he had a language insight - but one you could have also gotten from the English.
"Saved" has a wide range of meanings. It doesn't always refer to eternal-salvation-in-heaven. For instance, when St. Peter was sinking in the water and asked Jesus to save him, he probably meant "pull me out of this water so I don't drown" rather than "I'd like to go to heaven when I die"
So, in this case, we see it as the beneficial effect that having children brings to women - teaching us to get in the habit of thinking of someone else besides (or even before) ourselves, etc. This can help develop spiritual disciplines, as well as psychological ones (who ever was happier because they always thought of themselves first?)
And, as Orthodox, while we believe Eternal Salvation is by grace as the Bible says, we also do not believe that works are unimportant or have nothing to do with Eternal Salvation. Rather like when a little kid "helps" Daddy carry a big suitcase. Yes, Daddy does the work, but yes, the little kid does his best to contribute (even if he gets in the way more than he helps ; ) So - we don't have any problem with the idea that the raising of children might bring us closer to Eternal Salvation.
Also, note what it does NOT say - it doesn't say that childbearing is the ONLY way for women to be saved. Only that it saves women : ) So your spinster friend need not worry if she has found other ways to lead a good, healthy, Christian life.
Hope that helps your discussion : )