Modified QUIPS items	Brandt 2014	Dello Russo 2013	Derraik 2015	Gaillard 2014	Gaillard 2016	Hochner 2012	Hrolfsdottir 2015	Jeffery 2006	Maftei 2015	Mingrone 2008	Oostvogels 2014	Perng 014	Sauder 2017	Tam 2018	Winham 2006
1. Study participation
Source of target population adequately described for key characteristics including age, gender, pregnancy characteristics	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
The method used to identify the study population is described adequately	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Recruitment period is stated	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	No
Place of recruitment (setting and location) is stated	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Inclusion and exclusion criteria are clearly defined	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	No
There is adequate participation in the study by eligible individuals >80%a	No	NA	NA	No	No	No	No	Yes	No	NA	No	No	No	No	NA
Baseline characteristics of the participants are collected including gestational age, birth weight, age, gender	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Summary: Study participation	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low	Moderate
2. Study attrition
All the included patients have outcome data, or the dropout rate is maximum 20%a	No	NA	NA	No	No	No	No	Yes	No	NA	No	No	No	No	NA
Attempts to collect information on participants who dropped outa	Yes	NA	NA	Yes	Yes	Yes	Yes	Yes	Yes	NA	Yes	Yes	Yes	Yes	NA
Reasons for lost to follow‐up are describeda	Yes	NA	NA	Yes	Yes	Yes	Yes	Yes	Yes	NA	Yes	Yes	Yes	Yes	NA
Key characteristics (age, gender, pregnancy characteristics) information on those lost to follow‐upa	Yes	NA	NA	Yes	Yes	Yes	Yes	Yes	Yes	NA	Yes	Yes	Yes	Yes	NA
There are no important differences between key characteristics and outcomes in participants who completed the study and those who did nota	Unclear	NA	NA	Unclear	Unclear	Yes	Unclear	Unclear	Unclear	NA	Unclear	Unclear	Unclear	Unclear	NA
Summary: Study attrition	Moderate	NA	NA	Moderate	Moderate	Low	Moderate	Low	Moderate	NA	Moderate	Moderate	Moderate	Moderate	NA
3. Prognostic factor measurement
Definition of maternal nutritional state (ppBMI and/or GWG) and the method of measurements are clearly described	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Method of measuring of maternal nutritional state is valid and reliableb	Yes	Partly	Partly	Partly	Partly	Partly	Yes	Partly	Partly	Partly	Partly	Partly	Yes	Yes	Yes
Continuous variables (ppBMI and/or GWG) are reported or appropriate cut points are used (GWG categories in accordance with the IOM recommendations)	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Method and setting of measuring maternal nutritional state are the same for all study participants	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
All the included participants have complete data for the maternal nutritional state	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Appropriate method was used to replace the missing data on maternal nutritional statec	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA
Summary: Measurement of the maternal nutritional state	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low
4. Outcome measurement
Definition of outcome: Fasting insulin level	Yes	Yes	Yes	Yes	Yes	Yes	Yes	NA	NA	Yes	NA	NA	Yes	Yes	Yes
Definition of outcome: HOMA‐IR	NA	Yes	NA	NA	Yes	NA	Yes	Yes	Yes	NA	NA	Yes	Yes	Yes	NA
Definition of outcome: Fasting glucose level	NA	NA	NA	NA	Yes	Yes	Yes	NA	NA	NA	Yes	NA	NA	Yes	NA
Valid and reliable measurement of outcome	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Method and setting of outcome measurement is the same for all study participants	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Summary: Outcome measurement	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low
5. Study confounding
Maternal age, as an important confounder is measured	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Maternal smoking habits during pregnancy, as an important confounder is measured	Yes	Yes	Yes	Yes	Yes	Yes	Yes	No	Yes	No	Yes	Yes	Yes	Yes	No
Maternal socioeconomic status/maternal educational level, as an important confounder is measured	Yes	Yes	No	Yes	Yes	Yes	Yes	Yes	Yes	No	Yes	Yes	No	No	No
Birth weight, as an important confounder is measured	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	No	Yes	Yes	Yes	Yes	No	Yes
Breastfeeding, as an important confounder is measured	No	Yes	No	Yes	Yes	No	No	No	No	No	Yes	Yes	No	Yes	No
Offspring's age, as an important confounder is measured	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Offspring's adiposity (weight or BMI or fat mass index), as an important confounder is measured	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	No
The measured confounding factors are clearly defined	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Valid and reliable measurement of confounders	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Method and setting of confounding measurement are the same for all study participants	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
An appropriate method was used for replacing missing confounder data (e.g., imputation)	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA
Important confounders are accounted for in the study design (e.g., initial assembly of comparable groups or matching)	Partly	Yes	Partly	Yes	Yes	Partly	Partly	Partly	No	No	Yes	Yes	Partly	Partly	No
Confounders considered important by the authors of the article, are accounted for in the analysis (e.g., appropriate adjustment, stratification, multivariate regression)	No	Yes	No	Yes	Yes	Partly	No	No	No	No	Yes	Partly	No	Partly	No
Summary: Study confounding	High	Low	High	Low	Low	Moderate	High	High	High	High	Low	Moderate	High	High	High
6. Statistical analysis and reporting
The analytical strategy is described in detail, the adequacy of the analysis can be judged	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Strategy for model building is appropriate and is based on a conceptual framework or model	Yes	Yes	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
The results are reported in detail, no selective reporting can be observed	Yes	Yes	Unclear	Yes	Yes	Yes	Unclear	Yes	Unclear	Unclear	Yes	Yes	Yes	Yes	Unclear
Summary: Statistical analysis and presentation	Low	Low	Moderate	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low	Low

Ratings: Items are rated with yes (low risk of bias), unclear (unknown risk of bias), partly (moderate risk of bias) or no (high risk of bias).

For the 1st–4th and the 6th domains: If two of the items were rated as unclear, partly or no, then the specific main domain was considered to carry moderate risk of bias. If three or more of the items were rated as unclear, partly or no, then the specific main domain was considered to be carrying high risk of bias. Because the reasons for lost to follow‐up (dropouts) were described in all prospective studies and they randomly affected the participants, the dropout rate higher than 20% was unlikely to cause selection bias (see domains 1st and 2nd).

For the 5th domain: If maximum one of the items was rated as no plus one or two were rated as partly, then the specific main domain was considered to be carrying moderate risk of bias. If two or more of the items was rated as no, then the specific main domain was considered to be carrying high risk of bias.

Abbreviations: BMI, body mass index; GWG, gestational weight gain; HOMA‐IR, Homeostatic Measurement Assessment for Insulin Resistance; IOM, Institute of Medicine; NA, not applicable due to study design; ppBMI, prepregnancy BMI.

^aItems only applicable in case of prospective studies. Retrospective ones were not assessed.

^bIn case of self‐reported maternal data the item was rated as partly. If data were measured or obtained from records, the item was rated as yes.

^cOnly those patients were included in the studies, who had appropriate data on maternal nutritional state. Therefore, this item was not assessed.