Chorionicity and Preterm Birth Risk in Twin Pregnancies

Takeaway

• Monochorionicity was associated with an increased risk of preterm birth at all gestations in women both symptomatic and asymptomatic for preterm labour.
• Among twin pregnancies asymptomatic for preterm labour and women with spontaneous preterm birth, monochorionicity was associated with preterm birth at gestations ≤34 and <37 weeks.

Why this matters

• Although it is well established that monochorionic twin pregnancies are associated with an increased risk of preterm birth, no systematic reviews exist evaluating this association.

Study design

• 39 studies (29,864 pregnancies) met eligibility criteria after a search across electronic databases.
• Funding: None disclosed.

Key results

• Monochorionicity was significantly associated with an increased risk of preterm birth in women asymptomatic and symptomatic for preterm labour at:
  • ≤28 weeks (OR, 2.14; 95% CI, 1.52-3.02);
  • ≤32 weeks (OR, 1.55; 95% CI, 1.27-1.89; I², 68%);
  • ≤34 weeks (OR, 1.47; 95% CI, 1.27-1.69; I², 60%); and
  • <37 weeks (OR, 1.66; 95% CI, 1.43-1.93; I², 65%).
• Among women asymptomatic for preterm labour, monochorionicity was significantly associated with preterm birth at gestations ≤34 weeks (OR, 1.85; 95% CI, 1.42-2.40) and <37 weeks (OR, 1.75; 95% CI, 1.22-2.53; I², 61%).
• In sensitivity analysis, monochorionicity was significantly associated with an increased risk of spontaneous preterm birth at ≤34 (OR, 1.25; 95% CI, 1.01-1.55) and <37 weeks (OR, 1.41; 95% CI, 1.13-1.78).

Limitations

• Heterogeneity among studies.
• Some studies included only spontaneous preterm birth, whereas most studies included data on both spontaneous and iatrogenic preterm delivery.

This clinical summary originally appeared on Univadis, part of the Medscape Professional Network.