Effects of parity on preterm delivery in twin gestations conceived with in vitro fertilization
Michael S Awadalla1, Wael H Salem1, Jacqueline R Ho1
1Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California, Los Angeles, California.
Objective:
To determine the relationship between prior obstetrical history and gestational age at delivery in a twin pregnancy.
Design:
Retrospective cohort study using the United States Society for Assisted Reproductive Technology Clinic Outcomes Reporting System database.
Setting:
Clinic-based data.
Patients:
Patients undergoing in vitro fertilization (IVF) in the United States with live delivery of twins.
Interventions:
None.
Main Outcome Measures:
The main outcome measures are median gestational age at delivery and rate of preterm delivery (before 37 weeks).
Results:
The median gestational age at delivery of IVF-conceived twins was 36.3 (interquartile rate 34.4, 37.6) weeks for nulliparous women, 35.9 (34.0, 37.1) weeks for parous women with a prior preterm birth, and 36.7 (35.1, 37.7) weeks for parous women without a prior preterm birth. The rate of preterm delivery was 61% for nulliparous women, 70% for parous women with a prior preterm birth, and 55% for parous women without a prior preterm birth.
Conclusions:
Parous women without a history of preterm delivery had lower rates of preterm delivery in a subsequent twin pregnancy than nulliparous women. Nulliparous women had lower rates of preterm delivery compared with parous women with a history of preterm delivery.
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