Pregnancy History

The recurrence risk for preterm birth ranges from 15-50% and is related to the number and gestational age of previous preterm deliveries.49 It has been assessed that women with previous preterm deliveries demonstrated a 2.5-fold increased risk for preterm birth in their next pregnancy.49 Women with early spontaneous preterm births are far more likely to have subsequent preterm births, and it has been postulated this may be due to underlying genetic or health causes that persist between pregnancies and/or persistent or recurrent intrauterine infections.50 Furthermore, an inter pregnancy interval of 6 months or less is associated with more than two times greater risk for preterm birth after adjustment for confounders.51,52 This may be related to lack of time for the uterus to return to previous size and form and/or maternal micronutrient depletion.