Looking beyond the obvious: a critical systematic review and meta-analyses of risk factors for fertility problems in a globalized world

Background: Well-established risk factors for fertility problems such as smoking have been included in fertility awareness efforts globally. However, these efforts neglect risks that women in low and middle-income countries (LMIC) face.

Objective: To address this gap, we identified eight risk factors affecting women in LMIC and the aim of the current review was to estimate the impact of these risks on fertility.

Methods: We conducted systematic reviews and where data was available meta-analyses. We searched Medline, Embase, Cochrane library, regional databases and key organizational websites (1946-June 2016, updated January 2018, latest update taking place in 2021). Two researchers screened and extracted data independently. We included all study designs that assessed exposure to risk in clinical or community-based samples and excluded studies without control groups. The outcome of interest was fertility problems (inability to achieve pregnancy or live birth and neonatal death). We calculated pooled effect estimates from reported effect sizes or raw data. We assessed study quality using the Newcastle-Ottawa Scale. We registered the review with PROSPERO, registration number CRD42016048497.

Results: We identified 2,418 studies and included 61 (57 in meta-analyses). Results revealed a nine-fold increased risk of inability to become pregnant in genital tuberculosis (OR 8.91, CI 1.89-42.12) and almost threefold in HIV (OR 2.93, CI 1.95-4.42) and bacterial vaginosis (OR 2.81, CI 1.85-4.27). A twofold increased risk of tubal-factor infertility in Female Genital Mutilation/Cutting–Type II/III (OR 2.06, CI 1.03-4.15) and increased post-natal mortality in consanguinity (stillbirth, OR 1.28, CI 1.04-1.57; neonatal death, OR 1.57, CI 1.22-2.02).

Strength and limitations: Reliability of results was bolstered by a rigorous systematic review methodology that is replicable but limited by methodological shortcomings of the available primary studies and the small number of studies in each meta-analysis.

Conclusions: The risk factors investigated appeared to impact the reproductive process through multiple biological, behavioural, and clinical pathways. Additionally, infection and pelvic inflammatory disease seemed to be common pathways for several risk factors. The complex multifactorial risk profile can be addressed by LMIC using a global health framework to determine which risk factors are significant to their populations and how to tackle them. The subsequent health promotion encompassing these relevant health indicators could translate into more prevention and effective early detection of fertility problems in LMIC. Finally, the findings of multifactorial risk reinforced the need to put fertility as an agenda in global health initiatives.