She said, her voice deliberately calm: “Things have changed, Theo. We haven’t much time now. The baby has started.” Theo said: “How long?” “You can’t always tell with a first labour. It might be only a few hours. It could be twenty-four. Julian’s in the very early stages but we have to find somewhere quickly.”
This is a great detail. On average, first births take about 18 hours; and second labors take around 8 hours, on average.