The state of research on a topic often consists of dozens, hundreds, or even thousands of scientific studies. Systematic reviews summarise the results of scientific studies. Among other things, they serve as a sound decision-making basis for the scientific evaluation of possible health risks.

They can also provide quantitative results by means of meta-analysis. In doing so, they assess how clearly the results of studies speak for or against a particular assumption. Systematic reviews assess potential sources of error along with the quality and reliability of the studies included.

Rules that make the procedure comprehensible are extremely important for conducting systematic reviews. Such rules specify how the systematic literature search is carried out or how the results of the studies are evaluated. The inclusion and exclusion criteria for the selection of studies are also presented in advance in a transparent and comprehensible manner. The international expert teams selected by the WHO published these rules in the form of a study protocol in advance for each systematic review. At the end, the results are also published according to established guidelines.

In contrast to systematic reviews, the scoping review is less rigorous.

Scoping reviews can have different goals. For example, they can show which studies exist on a topic, which concepts have been examined, or where there are still gaps in knowledge.

A scoping review can also map the key concepts (theoretical assumptions, methods) of a research area, create work definitions, or define the boundaries of a topic. The quality of the studies included is usually not taken into account

A narrative review summarises the existing studies on a specific topic and interprets them, whereby the studies are subjectively selected and evaluated. In contrast to systematic reviews, narrative reviews lack systematic literature research and consideration of the quality of the studies included. The methodology of a narrative review is also less structured than that of a scoping review.

Because narrative reviews are more subjective and less systematic, they are less informative. A biased presentation of the state of research cannot be ruled out, and narrative reviews often do not reflect the entire evidence on a topic.

Objective

The systematic review was published under the title “Effects of Radiofrequency Electromagnetic Fields (RF-EMF) exposure on pregnancy and birth outcomes: A systematic review of experimental studies on non-human mammals” in Environment International on 30 August 2023.

The study summarises research on whether RF-EMF affect female fertility, pregnancy, and offspring. The studies investigated mammals in animal experiments. In addition to the fields in mobile communications, other RF-EMF were considered.

Results

No reliable evidence has been found that the EMF of mobile phones influence the female fertility of mammals or have a negative effect on the future offspring.

According to the authors, the systematic review does not provide sufficient evidence for impairment of female fertility, pregnancy, and offspring. The fields may, however, slightly reduce foetal weight. One possible reason is that the animals were exposed to relatively strong EMF during the experiments. On average, exposure was considerably higher than in everyday life and exceeded recommended limits.

It is possible that deficiencies in the studies were responsible for the results. Most of the meaningful results showed a high risk of bias. These systematic errors include inaccuracies in measurement or statistics. Moreover, results from animal studies are not easily transferable to humans.

Evaluation of the BfS

Because of the varying quality of studies, the Federal Office for Radiation Protection (BfS) recommends further research to meet high standards. Not just more studies but, above all, better studies are needed.

The systematic review allows the BfS to better assess the specific research needs on this topic.

A detailed evaluation of the systematic review can be found in the Spotlight on EMF.