Waiting more than five years between pregnancies is linked to a slightly higher chance of delivering early compared to waiting less than six months, though the risk is much lower than with very short intervals.
Evidence from Studies
No evidence studies found yet.
What Would Prove This
Per GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this claim, ordered from strongest to weakest.
A systematic review of RCTs could determine whether intentionally extending IPI beyond 60 months causally increases preterm birth risk.
A systematic review of randomized trials assigning women to conceive after 60+ months versus 24–29 months, with preterm birth as the primary outcome, controlling for maternal age, ovarian reserve, and prior pregnancy complications.
An RCT could determine whether delaying conception beyond 60 months increases preterm birth risk compared to moderate intervals.
A multicenter RCT assigning 2,000 women to conceive after 60+ months versus 24–29 months, with preterm birth before 37 weeks as the primary outcome, and adjustment for maternal age, fertility treatments, and chronic disease burden.
A prospective cohort could confirm whether very long IPIs independently predict preterm birth after adjusting for maternal aging and comorbidities.
A prospective cohort of 8,000 women aged 25–45, tracking IPI from delivery to next conception, with preterm birth as outcome and adjustment for maternal age, BMI, hypertension, and prior preterm birth history.
A case-control study could compare IPI distributions in women with preterm births after long intervals versus those with term births.
A matched case-control study of 1,500 preterm births after IPI >60 months and 3,000 term births, matched for maternal age, parity, and prior preterm history, with IPI verified via birth registry data.
A cross-sectional survey could estimate the prevalence of very long IPIs among women with preterm births.
A national survey of 50,000 women with at least two births, asking about timing of prior births and outcomes, with preterm birth confirmed by medical records.