Early term birth is associated with the risk of preterm and recurrent early term birth in women with 3 consecutive deliveries.

BACKGROUND We assessed the association of early term at first birth (ETB) with the risk of preterm birth (PTB) and ETB in women with 3 consecutive deliveries. METHODS We conducted a retrospective cohort study of all women with 3 consecutive singleton births at a single institute from 1994 to 2013. The risk of PTB (<37 weeks), spontaneous PTB and ETB (37-38 weeks) in the 3rd delivery was explored. RESULTS Of 49,259 women delivered in our center during the study period, 4038 met inclusion criteria. The rate for subsequent PTB, spontaneous PTB and recurrent ETB in the 3rd delivery significantly increased as the number of prior ETBs increased. The order of a single prior ETB in one of the first two deliveries was differently associated with the risk of complications in the 3rd delivery, which was higher when the prior ETB was more recent to the third delivery. CONCLUSION A history of ETB is associated with the risk of future PTB and recurrent ETB. The risk is related to the number and order of prior ETBs.