Linden 2017.

Study characteristics
Methods	RCT
Participants	Participants: women with Type 1 diabetes were recruited between November 2011 and December 2014 in their first or early second trimester of pregnancy (n = 174) Age range: >18 years Recruitment: women with Type 1 diabetes were recruited in their first or early second trimester of pregnancy and registered at one of the six participating study centres. Eligibility: literate and Swedish speaking pregnant women aged >18 years with a diagnosis of Type 1 diabetes and registered at one of the six participating study centres. Country: Sweden
Interventions	Intervention: multi‐component (n = 83) Web support with evidence‐based information, self‐care diary and communication with pregnant women with Type 1 diabetes in addition to standard care Control: non‐social media (n = 91) Standard care during pregnancy, childbirth and immediately after. Standard care varied, although all clinics offered frequent contact with midwives, obstetricians and endocrinologists during pregnancy, and one follow‐up visit after childbirth.
Outcomes	The primary outcomes (mean difference, measured at 6 months after childbirth) were well‐being and diabetes management.The secondary outcomes were psychometric scales measuring psychosocial variables and medical outcomes including Hypoglycemia fear, Diabetes‐related distress, and self‐perceived health. HbA1c values The intervention group evaluated the web‐based support using a structured questionnaire also containing a free‐text alternative.
Equity	High‐income country. Pregnant women with a diagnosis of Type 1 diabetes
Notes	Health behaviours: not applicable. Body function: HbA1c was the only outcome reported for this category. Psychological health: diabetes distress was the only outcome reported for this category. Well‐being: well‐being was the only outcome reported for this category. Mortality: not applicable. Adverse effects: not applicable. Secondary outcomes: self‐efficacy in diabetes management, self‐perceived health, sense of coherence, and fear of hypoglycaemia were the only outcomes of interest reported for this category.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomisation sequence generation not described. The authors state "randomly allocated (1:1) by the study midwife to the intervention group or the control group, using block randomization"
Allocation concealment (selection bias)	Low risk	Quote:"Using block randomization with prepared closed envelopes"
Blinding of personnel	Low risk	The diabetes midwives in charge of the random allocated sequence at the centres are not involved in the preparation of the envelopes, the use of web‐based support or in the statistical analyses.
Blinding of participants	High risk	Due to the nature of this trial it is not possible to blind the participants.
Blinding of outcome assessment (detection bias) All outcomes	High risk	One limitation of the study is that it is not feasible to blind members of the healthcare team to group allocation. Some outcomes are self‐reported and participants were not blinded.
Incomplete outcome data (attrition bias) All outcomes	Low risk	The dropout rate was high but not unexpected, and increased with miscarriages, neonatal and infant deaths. The participants included in the intention‐to‐treat analysis consisted of 158 women (intervention group, n = 78; control group, n = 80)
Selective reporting (reporting bias)	High risk	Outcomes in protocol but not in paper: self‐rated health, breastfeeding rate, experiences of nursing.
Baseline characteristics similar	Low risk	In the intervention 74.4% administered insulin via multiple injections versus 53.8% in the control group (P = 0.01). Adjusted for in analysis
Baseline outcome measurements similar	High risk	Well‐being measured with WBQ12 differed at baseline (i.e. in early pregnancy), with the control group scoring lower (P = 0.05; Table 2). Not adjusted for in analysis.
Protection against contamination	High risk	The research group has no way of monitoring and/or limiting access to other web‐based forums in relation to diabetes or childbearing during the study period.