We had male factor infertility and were told that my DH's sperm count was similar to someone who had a vasectomy, so we had a very small chance of failing pregnant naturally. After DS1 was born we didn't use any contraception and accepted that we might have a small age gap if we did have a miracle. So we'd be having unprotected DTD for about 1 year when we started IVF that led to DS2. Again, we didn't use contraception and we were delighted/excited/freaked out to conceive DD naturally when DS2 was 9 months.

ATM we are roughly avoiding DTD near ovulation, but we are planning on properly "trying" naturally soon for number 4. We know we have a fairly small chance of having another natural pregnancy but we are willing to try for a year or two or three. We probably wouldn't do IVF again though, because of the cost, the toll on my body and also we aren't willing to discard any embryos (every embie gets a go!) but we don't want a zillion children.