Preterm birth risk in twin pregnancy and the role of prior pregnancy outcome: not a simple 'yes' or 'no' answer.

Obstetrics has long been guided by the tenet, accurate or not, that if a complication occurred in a prior pregnancy, it is likely to recur in a subsequent pregnancy. Women with singleton, as well as twin, gestations who have had a prior singleton PTB are more likely to have a subsequent PTB, with increasing risks for earlier gestational ages of the prior PTB. As interventions to prevent PTB in twins are of limited proven efficacy, better methods of risk stratification may allow for heightened vigilance and more targeted interventions in those at highest risk. [Extracted from the article]