IMPLICATIONS OF IDIOPATHIC PRETERM DELIVERY FOR PREVIOUS AND SUBSEQUENT PREGNANCIES

Objective: To describe the relationship between pregnancy complication s and fetal outcome in first and second pregnancies, focusing on idiop athic and indicated preterm birth of singleton infants in either pregn ancy. Methods: Included in the study were 13,967 women in Denmark who gave birth to their first singleton infant in 1982 and a second infant in 1982-1987. Information on pregnancy and birth was obtained by link ing the National Medical Birth Register and the National Register of H ospital Discharges, based on personal identification numbers. Results: The risk of a preterm second birth in women with idiopathic and indic ated preterm first birth did not differ significantly (15.2 and 12.8%, respectively). However, women with idiopathic preterm birth in the fi rst pregnancy tended to repeat idiopathic preterm birth twice as often as women with indicated preterm birth repeated indicated preterm birt h (11.3 versus 6.4%). Adjustment by logistic regression analysis for o ther risk factors for preterm birth did not influence the relative ris k (6.0 before 32 weeks and 4.8 for 32-36 weeks) of a second preterm bi rth after a first preterm birth. Women with idiopathic preterm deliver y in their first and second pregnancies gave birth to infants with low er birth weight than in previous or subsequent pregnancies. Emergency cesarean delivery in a first term pregnancy was a risk factor for subs equent idiopathic preterm birth. Conclusion: Idiopathic preterm birth is associated with emergency cesarean delivery at term in previous pre gnancies and infants with lower birth weight in previous and subsequen t pregnancies.