Risk factors for ectopic pregnancy occurrence: Systematic review and meta-analysis

Abstract

Background: Given the high incidence of ectopic pregnancy (EP) in the general population and the high maternal morbidity and mortality rates associated with it, determining risk factors for the occurrence of EP is essential for directing attention and care to risk groups, aiming for early diagnosis, favorable outcomes, and the development of prevention strategies.

Objectives: The aim of this study was to identify risk factors for the occurrence of EP.

Search strategy: A systematic review with meta-analysis was performed on the electronic databases MEDLINE/PubMed, LILACS, The Cochrane Library, and Virtual Health Library (VHL), searching the following terms "Ectopic Pregnancy" or "Ectopic Gestation" and "Risk Factors" or "Predisposing Factors".

Selection criteria: The inclusion criteria were observational studies published in English and Portuguese. We excluded studies with undefined methodology and those published before the year 2000.

Data collection and analysis: The authors independently read the titles, abstracts, and full texts, using pre-defined inclusion and exclusion criteria, and discussed any differences. Data extraction and assessment of methodological quality were performed by each author in a standardized way. Sixteen risk factors were evaluated. The meta-analysis calculations were performed using the Reviewer Manager 5.3 software (RevMan 5.3).

Main results: The study found 715 studies, of which 11 were selected for review. The surveys were conducted between 2003 and 2019 and included 25 051 patients. The study revealed that several factors were strongly associated with the occurrence of EP. These included EP history (OR 9.03; 95% CI: 7.18-11.35; I² = 67%), pelvic inflammatory disease (OR 4.00; 95% CI: 3.46-4.61; I² = 0%), infertility (OR 3.70; 95% CI: 3.23-4.23; I² = 48%), abdominal and pelvic surgeries (OR 5.60; 95% CI: 4.83-6.49; I² = 81%), and previous tubal ligation (OR 5.59; 95% CI: 2.49-12.55; I² = 0%). Furthermore, the study showed that advanced maternal age, smoking, number of partners exceeding one, history of spontaneous and induced abortion, previous use of emergency contraception, and intrauterine device, demonstrated a slightly increased risk. Advanced maternal age within the range of 30-34 years (OR 1.13; 95% CI: 1.03-1.24; I¹ = 11%) and ≥ 40 years (OR 1.46; 95% CI: 1.19-1.78; I¹ = 88%), marital status (OR 1.19; 95% CI: 1.03-1.37; I² = 88%), and the use of oral contraceptives (OR 0.77; 95% CI: 0.66-0.90; I² = 86%) were also found to be associated with a slightly increased or decreased risk of EP, respectively. The impact of condom use on the occurrence of EP seems to be very limited (OR 0.93; 95% CI: 0.83-1.05; I² = 83%).

Conclusion: Based on the study findings, it is suggested that the presence of strong risk factors warrants the implementation of a screening policy for EP among these women.

Keywords: ectopic pregnancy; female contraception; infertility; maternal age; meta‐analysis; risk factor; systematic review.