The relationships between change in marital status between two consecutive births and adverse pregnancy outcomes at the second birth were investigated using linked Washington State 1980-93 white singleton birth certificates. Women who were married at the first birth had lower low birthweight (LBW) and small-size-for-gestational-age (SGA) rates at that birth than single women, and women married at the second birth had lower LBW, SGA and preterm delivery rates at that birth regardless of marital status at the first birth. Adjusted relative risks (RR) of LBW and SGA were significantly increased for initially married women who were single at the second birth compared with those who remained married (RR = 1.4 and 1.3, respectively). Risks of LBW and SGA were significantly decreased among initially single women who married by the second birth, compared with those remaining single (RR = 0.7 for LBW and 0.8 for SGA). We conclude that the largely unstudied subgroup of previously married women is at increased risk for adverse pregnancy outcomes. Public health policy and programmes directed at high-risk mothers and infants should be aware of the specific physical and emotional needs of this group of child-bearing women.