Recurrent miscarriages raise risk of preterm birth

Women with recurrent pregnancy loss are likely to deliver preterm in subsequent pregnancies, a study has found.

Researchers conducted a systematic review and meta-analysis to examine the impact of recurrent pregnancy loss on the risk of preterm birth. They searched multiple online databases for relevant studies and identified 18 for inclusion in the meta-analysis.

The total study population comprised 58,766 women with a history of recurrent pregnancy loss and 2,949,222 women without such a history (controls). Pooled data, obtained using a random-effects meta-analysis, showed that a history of recurrent pregnancy loss increased the odds of preterm birth in subsequent pregnancies by 60 percent (odds ratio [OR], 1.60, 95 percent confidence interval [CI], 1.45–1.78; I², 85.6 percent).

A trend of increase in the odds of preterm birth was observed with increasing number of pregnancy losses: two (pooled OR, 1.31, 95 percent CI, 1.09–1.57; I², 88.9 percent); two or more (pooled OR, 1.58, 95 percent CI, 1.27–1.96; I², 71.7 percent); and three or more (pooled OR, 1.81, 95 percent CI, 1.58–2.07; I², 73.6 percent).

Of note, the risk of preterm birth was pronounced in the subgroup of patients with unexplained recurrent pregnancy loss (pooled OR, 2.05, 95 percent CI, 1.46–2.89; I², 21.0 percent).

There were inconsistent adjustment for confounders and significant heterogeneity noted across the studies.