Preterm birth in twins after subfertility treatment: population based cohort study

Area of Science:

• Reproductive Medicine
• Perinatology
• Obstetrics

Background:

• Subfertility treatments, including ovarian stimulation and in vitro fertilization (IVF), are increasingly used for twin conception.
• Understanding the impact of these treatments on gestational length and preterm birth is crucial for maternal and neonatal outcomes.

Purpose of the Study:

• To compare gestational length and preterm birth rates between medically and naturally conceived twins.
• To determine the influence of zygosity and chorionicity on gestational length in twins conceived through assisted reproductive technologies.

Main Methods:

• A population-based cohort study was conducted, analyzing 4368 twin pairs born between 1976 and 2002.
• Data included spontaneously conceived twins, and those conceived after ovarian stimulation or IVF/intracytoplasmic sperm injection (ICSI).
• Gestational length and preterm birth prevalence were the primary outcome measures.

Main Results:

• Twins from subfertility treatments had a slightly shorter gestational age (mean difference 4.0 days) and increased odds of preterm birth (OR 1.6).
• The increased risk was primarily for mild preterm birth (34-36 weeks).
• Dizygotic twinning significantly reduced the risk of prematurity, leveling off the overall increased risk associated with subfertility treatments.

Conclusions:

• Assisted reproductive technologies are associated with a higher risk of mild preterm birth in twins.
• Dizygotic twinning plays a protective role, substantially reducing the risk of prematurity in twins conceived through subfertility treatments.