I'd say baby. DPs hours got cut right down last year - we had enough to pay the mortgage plus about $30 p/wk for bills and food, sometimes not even that. I was pregnant and we had a toddler. We made do, it was definitely not easy but it wasn't terrible either.
Put in a small vege garden, make your own cleaners, eat simply - as an extra benefit you'll be healthier
Remember you get quite abit more WFF with a second baby plus that extra 8 week payment so you might actually end up better off financially than if you went to work.