The goal of this clinical trial is to evaluate the effectiveness of training pregnant women on the decision of having an oral glucose challenge test (GCT), which is recommended by a physician for screening of gestational diabetes mellitus (GDM). Primary hypothesis is that structured training is effective in increasing pregnant women's acceptance of gestational diabetes mellitus (GDM) screening. The effect of training on patients' decision-making regarding gestational diabetes mellitus (GDM) screening was planned to be evaluated. Participants in the control group received standard counseling about GDM screening. Participants in the intervention group received a structured, specific audiovisual educational program supported by a guidebook, lasting approximately 15-20 minutes.

This is a randomised controlled intervention study. This was conducted at Zeynep Kamil Women's and Children's Diseases Training and Research Hospital, in İstanbul, Türkiye, between January-July 2019. Ethical permission was obtained from the Hospital's Ethics Committee (Approval date/number: 07.11.2018/141). The formal study permission was obtained from the İstanbul Province Health Directorate because the hospital was an governmental hospital. All eligible participants were informed and they were invited to the study and the accepted participants signed their consents.

Antenatal follow-up in Türkiye is conducted in accordance with the Ministry of Health's Prenatal Care Management Guide. This guidance recommends 50 g glucose challenge test (GCT) between 24-28 weeks for pregnant women who are not at high risk.

The target group of the study consisted of pregnant women who applied to the outpatient clinics of the hospital in İstanbul. Pregnant women over the age of 18, between the 24-28th weeks of pregnancy, who could speak Turkish, were literate were included in the study. Pregnant women diagnosed with diabetes before pregnancy, in the first trimester or third trimester, with speech and hearing impairments, and those who were not literate in Turkish were excluded from the study.

The sample size was calculated with the Open-Epi program. Hospital electronic data for 2017 was reviewed and it was determined that only 40% of pregnant women who were recommended 50 g GCT had the test. The sample calculation was made with the expectation that this rate would increase to 60% with the training planned in the study. The number of pregnant women to be included in the study was calculated as 98 for each group, 196 in total. The probability of lost to follow-up was calculated as 40% and the sample size was increased to 280(140+140).

Patient recruitment was conducted between May and June 2019. Two hundred and five volunteer pregnant women who met the inclusion criteria, had not yet been diagnosed with diabetes mellitus according to national and international guidelines, and were recommended for GCT were invited to participate in the study. They were randomly assigned to two groups: control (n=101) and intervention (n=104). Participants were randomly assigned to either the intervention group or the control group in a 1:1 using a simple coin toss method. Outpatient examination time was 15 minutes. Pregnant women were given standard information about GCT during this time. The GCT was recommended verbally, directly to control group. Pregnant women assigned to the intervention group were invited to trainings.

The trainings were held in a room arranged for this purpose in the hospital, with one participant, by the same researcher (first author), lasted about 15 minutes and were applied in mutual communication with the questions of the participants. The materials which used were an Audio-Visual Aid/Pictured Guide Book prepared for this study and named as Gestational Diabetes Pregnant Education Guide, a transparent package containing 50 g glucose powder and a commercially packaged 50 g glucose drink package.

The training guide book was prepared by authors. The educational materials were prepared by two obstetrics and gynecology specialists and one public health expert with over 15 years of experience in their fields. The GDPEG was prepared in a power point program and consisted of 14 sheets and 28 pages. The odd-numbered pages were arranged to be seen and understood by the patient. The even- numbered pages contained the information to be explained by the educator. The GDPEG was placed in a presentation folder that enabled face-to-face training.

Researchers prepared transparent packets containing an amount of glucose corresponding to the amount of glucose in the solution used in diabetes screening tests. Participants were also shown commercially prepared packets containing the same amount of glucose. The purpose of visually sharing the packets was to inform the pregnant about the amount of glucose used in the test and to allow them to compare it to their daily consumption.

The same experienced obstetrician and gynecologist on the study team provided verbal information regarding the test given to the control group.

Data collected at the first admission to the hospital by face to face from all pregnant women eligible and accepted to the invitation of this study. All pregnant women who agreed to participate in the study were asked to complete a data collection tool. The results of whether they had GCT or not were obtained from hospital registration system.

The test results were confirmed from electronic records within 2-16 weeks after the examination. The results of the pregnant women who had the test done in our hospital were obtained from the hospital registry system. Pregnant women whose test results could not be seen in the hospital registry system, were contacted by phone to find out whether they had the test done at another center. The test results were requested as a document from the pregnant women who had the test.

Inclusion Criteria:

• Pregnant women over the age of 18,
• Between the 24th and 28th weeks of gestation,
• Who could speak and be literate in Turkish.

Exclusion Criteria:

• Pregnant women diagnosed with diabetes before pregnancy,
• Patients with speech and hearing impairments, and those not literate in Turkish.

During the ethics committee approval process for the study, it was declared that personal data would only be shared with members of the ethics committee and the study team. Upon request, individual participant data (IPD) can be shared following approval from the ethics committee and in accordance with its authorization.