Family size in the colony was large by modern American standards, though childbirth was often spaced out, with an average of two years between children. Most families averaged five to six children living under the same roof, though it was not uncommon for one family to have grown children moving out before the mother had finished giving birth. Maternal mortality rates were fairly high; one birth in thirty ended in the death of the mother, resulting in one in five women dying in childbirth. However, "the rate of infant mortality in Plymouth seems to have been relatively low." Demos concludes that "it appears that the rate of infant and child mortality in Plymouth was no more than 25 per cent".