BACKGROUND AND PURPOSE:

• There is no consensus on how long to wait prior to attempting pregnancy after fetal loss
• As the age of first pregnancy continues to rise in some parts of the world, waiting may be detrimental
• Sundermann et al. (Obstetrics & Gynecology, 2017) sought to determine whether interpregnancy interval length after pregnancy loss is linked with higher risk of repeat miscarriage

METHODS:

• Prospective cohort study (2000-2012)
• Eligibility: Early in pregnancy or planning pregnancy, whose most recent pregnancy before enrollment ended is miscarriage
  • All women enrolled prior to 12 weeks gestation
  • No use of assisted reproductive technologies
  • Dating by first trimester ultrasound
• Miscarriage: Defined as loss before 20 weeks of gestation
• Primary outcome: Pregnancy loss before 20 weeks gestation in the study pregnancy
• Adjusted models included maternal age, race, parity, body mass index, and education

RESULTS:

• Of the 514 women participating in the study, 15.7% had repeated miscarriage
  • Median gestation age 9 weeks
• Median maternal age was 30 years and 55.6% of participants had at least one previous livebirth
• 9% had ≥ losses at time of enrollment
• When compared with women with interpregnancy intervals of 6–18 months
  • Intervals < 3 months associated with lowest risk of repeat miscarriage (7.3% compared with 22.1%; adjusted hazard ratio 0.33, 95% CI 0.16–0.71)
  • Risk was not modified by maternal race nor parity
• Trend showed similar results when interpregnancy interval was analyzed as as a continuous variable
  • Risk of subsequent miscarriage lowest for women with short interpregnancy intervals and increasing with longer intervals until reaching a peak at 6 months

CONCLUSION:

• A shorter interpregnancy interval of less than 3 months was associated with the lowest risk of subsequent miscarriage
• Authors suggest various biologic mechanisms, including that the body may be primed for pregnancy in the few months after miscarriage
• Delaying conception to reduce miscarriage risk is not advisable

Learn More – Primary Sources:

Interpregnancy Interval After Pregnancy Loss and Risk of Repeat Miscarriage

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