- Preterm birth may be triggered by an interaction between uterine size and increasing uterine load (UL).
Why this matters
- Preterm birth is the leading cause of adverse pregnancy outcomes.
- Model 1:
- The timing of birth was more sensitive to maternal height (MH) in twin pregnancies;
- A shorter mother with a twin pregnancy delivered earlier than expected for singleton pregnancies (OR, 56.2; 95% CI, 44.7-70.9).
- Model 2:
- The timing of birth was more sensitive to MH in singleton pregnancies with large for gestational age (LGA) fetuses than singleton pregnancies with small for gestational age (SGA) fetuses;
- A shorter mother with a LGA pregnancy delivered earlier than expected based on the trend for SGA pregnancy (OR, 10.2; 95% CI, 5.84-17.0).
- Retrospective cohort study.
- Uncomplicated pregnancies identified from the Swedish Medical Birth Register (n=530,888).
- The relationship between UL (LGA, twin pregnancy vs singleton pregnancy), MH, and gestational age at birth was explored.
- Funding: Swedish government grants to researchers in the public health sector; Swedish Research Council; March of Dimes Foundation; Burroughs Wellcome Fund Preterm Birth Research Grant.
- Maternal height is used as a proxy for uterine size.