Table 3.
Characteristics of included studies according to the comparison of intervention strategies
| Author, year (Study design) | Country (Municipality/Province, City) [Recruitment period] | Participant characteristics | Number of participants | Additional dietary intervention details on intervention group (duration) | Compliancea | Outcome of interest |
|---|---|---|---|---|---|---|
| Comparison: Food exchange of all food groups versus individualised dietary intervention | ||||||
| Chen (2017)63 (RCT) | China (Foshan, Guangdong) [May 2015–July 2016] |
Age: [I] 28.2 ± 4.8 [C] 28.1 ± 4.6 Week gestation: [I] 27.3 ± 1.1 [C] 27.1 ± 1.2 |
[I] 59 [C] 59 |
Since diagnosis | — | FG, 2‐hour BG and HbA1c |
| Ma (2011)60 (RCT) | China (Xinjiang, Ürümqi) [January 2009–December 2010] | First GDM diagnosis, no insulin treatment at baseline, no other medical conditions |
[I] 43 [C] 43 |
Macronutrients composition: CHO: 45–50%, fat: 20–30% and protein: 20–25% (since diagnosis) |
Review appointment till delivery. Glucose target: 1‐hour BG <8 mmol/L |
Macrosomia |
| Zhang (2013)64 (Cohort study) | China (Zhejiang, Ningbo) [2008–2012] |
Age: [I] 28.4 ± 2.1 [C] 27.9 ± 2.1 BMI: [I] 22.4 ± 2.7 [C] 22.7 ± 2.2 Week gestation: [I] 24.6 ± 0.5 [C] 24.4 ± 0.7 |
[I] 123 [C] 75 |
Macronutrients composition: CHO: 50–60%, fat: 25–30% and protein: 15–20% (since diagnosis) | Review appointment till delivery | FG, 2‐hour BG, caesarean section, macrosomia and preterm birth |
| Zhang (2015a)65 (Cohort study) | China (Zhejiang, Ningbo) [January 2013–September 2014] |
Age: [I] 28.76 ± 2.1 [C] 28.36 ± 1.1 Week gestation: [I] 26.1 ± 2.2 [C] 25.8 ± 1.4 |
[I] 226 [C] 122 |
Macronutrients composition: CHO: 50–60%, fat: 25–30% and protein: 15–20% (since diagnosis) | Taught about glucose target: FG ≤5.3 mmol/L; 2‐hour BG ≤6.7 mmol/L, without specifying whether review occurred | FG, 2‐hour BG, HbA1c, caesarean section, macrosomia, respiratory distress and preterm birth |
| Comparison: Low GI diet versus individualised dietary intervention | ||||||
| Hu (2014)54 (RCT) | China (Guangdong, Guangzhou) [October 2011–April 2013] |
Between 23 and 35 week gestation Age: [I] 30.3 ± 4.9 [C] 29.7 ± 3.7 BMI: [I] 21.2 ± 2.5 [C] 20.9 ± 3.4 |
[I] 66 [C] 74 |
Replacing rice with low GI staple food and keeping others the same between groups (Day 2 to Day 5 of hospitalisation) | Diet offered in hospital with record of food consumption | FG |
| Liu (2015)66 (RCT) | China (Beijing) [January 2014–December 2014] |
Age: [I] 30.1 ± 3.3 [C] 30.3 ± 3.4 BMI: [I] 23.2 ± 3.7 [C] 23.3 ± 3.7 |
[I] 258 [C] 260 |
Choosing low GI food alternatives in main meal (since diagnosis) | Review at clinic once in every 2 weeks | FG, 2‐hour BG, pre‐eclampsia, caesarean section, macrosomia, preterm birth, respiratory distress and hypoglycaemia |
| Liu (2018)67 (RCT) | China (Gansu) [June 2012–June 2017] |
Age: [I] 25.3 ± 2.3 [C] 26.3 ± 1.6 Week gestation: [I] 25.7 ± 2.4 [C] 24.1 ± 3.7 |
[I] 33 [C] 33 |
Choosing low GI food alternatives in main meal (since diagnosis) | — | FG, 2‐hour BG, HbA1c, macrosomia, preterm birth, respiratory distress and hypoglycaemia |
| Wang (2016a)68 (Cohort study) | China (Nanchong, Sichuan) [January 2015–January 2016] |
Age: [I] 30.6 ± 5.1 [C] 31.6 ± 4.1 Week gestation: [I] 26.0 ± 3.2 [C] 25.7 ± 3.4 |
[I] 70 [C] 58 |
Choosing low GI food alternatives (since diagnosis) | Routine review appointment till delivery | FG, 2‐hour BG, HbA1c and hypoglycaemia |
| Wu (2014)69 (RCT) | China (Hubei, Wuhan) [December 2010–December 2012] | GDM diagnosis at 24–28‐week gestation, no other medical conditions and would deliver in this hospital |
[I] 86 [C] 80 |
Choosing lower GI food alternatives (4 weeks) | Telephone review once a week | FG, HbA1c, caesarean section, macrosomia, preterm birth, respiratory distress and hypoglycaemia |
| Wu (2015)70 (RCT) | China (Guangdong, Guangzhou) [January 2011–May 2013] |
GDM diagnosis at 24–25‐week gestation Age: [I] 30.5 ± 3.8 [C] 29.7 ± 4.4 |
[I] 69 [C] 79 |
Choosing low GI food alternatives (8 weeks) | — | FG, 2‐hour BG |
| Comparison: Low GL diet versus individualised dietary intervention | ||||||
| Gai (2012)71 (RCT) | China (Hebei, Shijiazhuang) [January 2008–October 2009] |
Age: 22–40 Week gestation: 36–40 |
[I] 60 [C] 60 |
Choosing lower GL alternatives with suggested cooking method (since entering into study) | — | FG, 2‐hour BG, HbA1c |
| Jiang (2016)72 (RCT) | China (Guangdong, Shenzhen) [January 2013–December 2014] |
Age: [I] 28.5 ± 4.8 [C] 28.4 ± 5.0 Week gestation: [I] 26.8 ± 1.8 [C] 26.7 ± 2.0 |
[I] 40 [C] 40 |
Choosing lower GL alternatives (since diagnosis) | Irregular clinic or telephone review | FG, 2‐hour BG, HbA1c |
| Li (2017)73 (RCT) | China (Hunan) [May 2013–April 2016] |
Age: [I] 29.1 ± 3.8 [C] 29.4 ± 3.7 |
[I] 58 [C] 56 |
Choosing lower GL alternatives (since diagnosis) | – | FG, HbA1c, caesarean section, preterm birth and respiratory distress |
| Ma (2015)57 (RCT) | China (Guangdong, Guangzhou) [June 2008–July 2009] |
Age: [I] 30.1 ± 3.8 [C] 30.0 ± 3.5 Week gestation: [I] 27.5 ± 1.1 [C] 27.9 ± 1.1 |
[I] 47 [C] 48 |
Choosing low GL alternatives (since diagnosis) | 3‐Days dietary recall to assess the compliance once every 2 weeks | FG, 2‐hour BG, HbA1c, macrosomia and preterm birth |
| Zhang (2015)74 (RCT) | China (Guangdong, Shenzhen) [January 2013–January 2014] |
GDM diagnosis in third trimester Age: [I] + [C] 28.4 ± 5.2 Week gestation: [I] + [C] 38.2 ± 1.2 |
[I] 46 [C] 46 |
Choosing lower GL alternatives (since diagnosis) | – | FG, 2‐hour BG, HbA1c |
| Comparison: Fibre‐enriched diet versus individualised dietary intervention | ||||||
| Lian (2014)75 (RCT) | China (Guangdong, Guangzhou) [June 2010–June 2012] |
Age: [I] + [C] 28.4 ± 3.2 |
[I] 76 [C] 72 |
Swapping one‐third to half of staple foods to buckwheat in four main meals daily (12 weeks) | — | FG, 2‐hour BG, HbA1c, macrosomia, respiratory distress and preterm birth |
| Luo (2016)76 (RCT) | China (Guangdong, Xingning) [June 2014–Dec 2014] |
Over 28‐week gestation Age: [I] 29.2 ± 3.5 [C] 28.8 ± 3.6 |
[I] 100 [C] 100 |
Wheat bran supplementation each time, three times daily (8 weeks) | — | FG, 2‐hour BG and HbA1c |
| Pan (2015)77 (RCT) | China (Jiangsu, Nantong) [September 2014–December 2014] |
Age: [I] 29.5 ± 7.8 [C] 28.8 ± 8.3 Week gestation: [I] 25.1 ± 3.0 [C] 25.1 ± 3.1 |
[I] 48 [C] 48 |
3.5 g wheat bran supplementation before each meal (4 weeks) | Review appointment weekly | FG, 2‐hour BG, macrosomia, preterm birth and hypoglycaemia |
| Wu (2010)78 (Cohort study) | China (Guangdong, Guangzhou) [July 2008–June 2009] | GDM diagnosed women without insulin use |
[I] 54 [C] 51 |
Swapping one‐third of staple foods to buckwheat in four main meals daily (4 days) | — | FG, 2‐hour BG |
| Yang (2015)79 (RCT) | China (Guangdong, Guangzhou) [June 2014–December 2014] |
More than 28‐week gestation. Age: [I] 29.1 ± 3.4 [C] 28.4 ± 3.5 |
[I] 90 [C] 90 |
3.5 g wheat bran supplementation each time, twice per day (4 weeks) | — | FG, 2‐hour BG, HbA1c and macrosomia |
| Comparison: DASH diet versus individualised dietary intervention | ||||||
| Yao (2015)61 (RCT) | China (Anhui, Hefei) [March 2014–October 2014] |
Age: [I] 30.7 ± 5.6 [C] 28.3 ± 5.1 BMI: [I] 30.9 ± 4.3 [C] 29.6 ± 5.3 Week gestation: [I] 26.9 ± 1.4 [C] 25.7 ± 1.3 |
[I] 17 [C] 16 |
Macronutrients composition: 45–55% CHO, 15–20% protein and 25–30% fat. Daily intake of sodium was 2400 mg (4 weeks) | Phone review once every week during intervention. Kept under observation after intervention until delivery | FG, caesarean section and macrosomia |
| Comparison: PUFA rich diet versus individualised dietary intervention | ||||||
| Wang (2015)62 (RCT) | China (Jiangsu, Changzhou) [January 2011–January 2013] |
GDM diagnosis at 24–28 week gestation. Age: [I] 30.3 ± 4.2 [C] 29.7 ± 4.6 BMI: [I] 21.4 ± 3.0 [C] 22.2 ± 3.6 |
[I] 41 [C] 43 |
PUFA‐rich diet (6–8 weeks) | Weekly telephone follow up | FG, 2‐hour BG, macrosomia |
| Comparison: Low GL diet versus food exchange of all food groups | ||||||
| Chen (2015)80 (RCT) | China (Hainan, Wenchang) [January 2012–January 2014] |
Age: [I] 32.0 ± 3.8 [C] 31.1 ± 3.6 BMI: [I] 21.8 ± 2.9 [C] 21.5 ± 3.7 |
[I] 72 [C] 73 |
Choosing lower GL food alternatives (since diagnosis to delivery) | Clinic review once in every 2 weeks | FG, 2‐hour BG, macrosomia, preterm birth and respiratory distress |
| Huang (2015)81 (RCT) | China (Guangdong, Dongguan) [January 2012–January 2014] |
Age: [I] 28.2 ± 8.9 [C] 27.0 ± 7.9 |
[I] 40 [C] 40 |
Choosing lower GL food alternatives (since diagnosis) | Clinic review once every week | FG, 2‐hour BG, respiratory distress, jaundice and hypoglycaemia |
| Shen (2010)82 (Cohort study) | China (Shanghai) [May 2008–Mar 2009] |
GDM diagnosis at 24–28‐week gestation Age: [I] 29.5 ± 3.2 [C] 29.0 ± 2.8 |
[I] 42 [C] 38 |
Choosing lower GL food alternatives (from diagnosis till delivery) | Offer review clinic and telephone query service | FG, 2‐hour BG, HbA1c, pre‐eclampsia, macrosomia, preterm birth, respiratory distress and jaundice |
| Sun (2013)83 (RCT) |
China (Guangdong, Guangzhou) [May 2012‐ Dec 2012] |
Women diagnosed with GDM |
[I] 78 [C] 80 |
Choosing lower GL food alternatives (2 weeks) | Review appointment once in one to 2 weeks. | FG, 2 hour BG. |
| Wu (2013)84 (RCT) | China (Jiangsu, Haimen) [June 2010–December 2011] |
28‐week gestation Age: 22–43 |
[I] 30 [C] 30 |
Choosing lower GL food alternatives (since diagnosis) | Review appointment per week | BGL, 2‐hour BG |
| Zhi (2012)85 (RCT) | China (Guizhou) [June 2011–November 2011] |
30‐week gestation Age: 23–40 |
[I] 23 [C] 22 |
Choosing lower GL food alternatives (since diagnosis) | Review fortnightly | FG, 2‐hour BG, caesarean section and macrosomia |
| Comparison: Low GI diet versus low GL diet versus food exchange of all food groups | ||||||
| Wang (2016)86 (RCT) | China (Jiangsu, Nantong) [May 2013–May 2014] |
Age: [GL] 26.6 ± 4.9 [GI] 26.4 ± 4.6 [C] 26.5 ± 4.9 Week gestation: [GL] 25.6 ± 2.8 [GI] 25.7 ± 2.8 [C] 25.9 ± 2.6 |
[GL] 43 [GI] 38 [C] 32 |
Choosing lower GL or lower GI food alternatives (since diagnosis) | Review appointment once every week | FG, 2‐hour BG, HbA1c, caesarean section, macrosomia and hypoglycaemia |
Information on dietary compliance was extracted to determine whether the study design appropriately considered and evaluated participants’ adherence to assigned dietary regime. Study design was examined to determine if dietary compliance included review appointment of dietary regime and meal or supplementation given with assessment of leftovers and other food intake. Any study reported no dietary follow up was rated as high risk of bias. Studies with no report on relevant information was considered as unknown dietary compliance.
BMI, pre‐pregnancy body mass index; C, control group; CHO, carbohydrate; DASH diet, Dietary Approaches to Stop Hypertension diet; FG, fasting plasma glucose; GDM, gestational diabetes mellitus; GI diet, glycaemic index diet; GL diet, glycaemic load diet; I, intervention group; PUFA, polyunsaturated fat; RCT, randomised controlled trial; 1‐hour BG: 1‐hour plasma glucose; 2‐hour BG: 2‐hour plasma glucose.