Birth outcomes after induced abortion: a nationwide register-based study of first births in Finland

STUDY QUESTION Is the perinatal health of first-born children affected by the mother's previous induced abortion(s) (IAs)? SUMMARY ANSWER Prior IAs, particularly repeat IAs, are correlated with an increased risk of some health problems at first birth; even in a country with good health care quality. WHAT IS KNOWN ALREADY A positive association between IA and risk of preterm birth or a dose–response effect has been found in some previous studies. Limited information and conflicting results on other infant outcomes are available. STUDY DESIGN, SIZE AND DURATION Nationwide register-based study including 300 858 first-time mothers during 1996–2008 in Finland. PARTICIPANTS/MATERIALS, SETTING AND METHODS All the first-time mothers with a singleton birth (obtained from the Medical Birth Register) in the period 1996–2008 (n = 300 858) were linked to the Abortion Register for the period 1983–2008. MAIN RESULTS AND THE ROLE OF CHANCE Of the first-time mothers, 10.3% (n = 31 083) had one, 1.5% had two and 0.3% had three or more IAs. Most IAs were surgical (88%) performed before 12 weeks (91%) and carried out for social reasons (97%). After adjustment, perinatal deaths and very preterm birth (