Prior Spontaneous or Induced Abortion Is a Risk Factor for Cervical Dysfunction in Pregnant Women: a Systematic Review and Meta-analysis

Abstract

A history of abortion is associated with cervical dysfunction during pregnancy, but there remains uncertainty about whether risk can be stratified by the abortion type, the abortion procedure, or number of previous abortions. The objective of this study was to verify the relationship between cervical dysfunction measures in pregnancies with and without a history of termination. Embase and Medline databases were searched from 01 January 1960 to 01 March 2022 resulting in a full-text review of 28 studies. The Newcastle–Ottawa Scale (NOS) was used to assess the quality and risk of bias for non-randomized studies. The meta-analysis consisted of 6 studies that met all inclusion and exclusion criteria and included a combined total of 2,513,044 pregnancies. Cervical dysfunction was defined as either cervical insufficiency/incompetence in 4 of the studies and as short cervix in the others. Results from a random-effects model using reported adjusted odds ratios (aOR) estimated an increase in the odds of 2.71 (95% CI 1.76, 4.16) for cervical dysfunction in the current pregnancy related to a history of induced or spontaneous abortion. Subgroup analyses with only induced abortions (surgical/medical) estimated an aOR of 2.54 (95% CI 1.41, 4.57), while studies limited to surgical abortions had an aOR of 4.08 (95% CI 2.84, 5.86). The risk of cervical dysfunction in the current pregnancy was also found to be dependent on the number of previous abortions. In this meta-analysis, a prior history of abortion, and specifically induced abortions, was associated with cervical dysfunction. The protocol was registered in PROSPERO (CRD42020209723).

Subsequent pregnancy outcomes after second trimester miscarriage or termination for medical/fetal reason: A systematic review and meta‐analysis of observational studies

“… 30 reported a similar trend when only considering second‐trimester losses after IVF conceptions. In addition, prior systematic reviews which considered specifically a history or prior termination or uterine evacuation or curettage surgical procedures and subsequent risk of cervical insufficiency 13 , 14 , 15 report an increased subsequent risk of preterm birth, which is in keeping with the evidence presented in this review. Of note, our findings must be interpreted with caution due to the low‐quality evidence when specifically, second trimester miscarriage only was considered.…”

“…It is plausible that preterm birth may be increased following late miscarriage given the evidence for such an association after late termination of pregnancy in the second trimester, 13 a prior preterm birth 12 and after recurrent first trimester losses 4,6 . The risk may relate to premature cervical dilatation or the abnormal initiation of labor as well as iatrogenic procedures performed 13 .…”

“…It is plausible that preterm birth may be increased following late miscarriage given the evidence for such an association after late termination of pregnancy in the second trimester, 13 a prior preterm birth 12 and after recurrent first trimester losses 4,6 . The risk may relate to premature cervical dilatation or the abnormal initiation of labor as well as iatrogenic procedures performed 13 . This review provides some evidence that such a hypothesis may be correct, but highlights significant paucity of evidence to confirm or refute whether there is a significant risk of preterm birth after second trimester miscarriage.…”

“…This systematic review of observational studies aimed to answer the research question: “Does a second trimester pregnancy loss (miscarriage or TFMR/TOPFA) lead to an increased risk of adverse perinatal and obstetric risks in the subsequent pregnancy?”. Prior systematic reviews 13 , 14 , 15 have highlighted an association with termination or uterine evacuative procedures and subsequent risk of preterm birth but, to the best of our knowledge, none have focused solely on spontaneous second trimester miscarriage or termination for TFMR/TOPFA.…”

Risk Factors for Spontaneous Preterm Birth are Mediated through Changes in Cervical Length

“…In a recent study by Gudicha et al an adjustment of the threshold to define a short cervix in the mid-trimester or later in gestation to account for maternal characteristics resulted in a substantial improvement in the sensitivity for prediction of women at risk for spontaneous preterm delivery (35). Thus, insight into the mechanism describing how maternal risk factors contribute to cervical shortening across pregnancy may provide an understanding on how maternal risk factors influence preterm birth (69,83,84).…”