Randomised controlled trials in women's health in the last two decades: A meta-review

Obstetric and gynaecological conditions represent a significant burden of disease, requiring clinical research. We aimed to study trends in the publication of randomised controlled trials (RCTs) in women's health over the last two decades. The primary objective was to describe longitudinal trends in the geographical distribution of RCTs in obstetrics and gynaecology. We also described trends in trial funding, publication sources and separately published trial protocols.

RCTs were identified by searching the Web of Science alone, due to the large number of results and descriptive nature of analyses. Using the filter tool, only studies labelled as "Clinical trial" or "Article" were included; all other document types were excluded. Trial protocols were identified and analysed separately. Indexing data were extracted using the Web of Science selection tools. As we aimed simply to describe research trends using a single platform, we did not check for duplicates. No process for data pooling was necessary. Correlation of GDP, funding and number of RCTs was calculated using Pearson's r test.

We identified 39,071 RCTs. The number of annual publications globally increased from 1,406 in 2001 to 1,979 in 2020. The US (n = 12,479) and the UK (n = 3,745) were responsible for the most RCTs, followed by Italy (n = 2,676) and China (n = 2,338). The largest percentage increase in annual publications was seen in Iran (n = 5 to n = 113, +2,160 %) and the Western Pacific Region (n = 16 to n = 171, +968.8 %). GDP was significantly correlated with the number of published RCTs in 2019 for the 25 most prolific countries (p < 0.001), but not with the proportion of RCTs funded.

Despite growing contributions from the Western Pacific and Eastern Mediterranean regions, most RCTs are still produced in a small nucleus of high-income countries. Increased international collaboration may benefit both high- and low-income countries.