Methods	Study design: Quasi‐experimental study
	Unit of randomization: Not specified
	Type of study: Obesity Prevention
Participants	Location/setting: Large tertiary hospital, Wuhan, China
	Population: Not specified
	Sample size: 90
	Drop outs/withdrawal: 11
	Socio‐demographics
	Mean (SD) age: Total: 26.85 (2.44), Intervention: 26.73 (2.67)
	Control: 27.11 (2.31)
	Occupation:
	Intervention:
	Office clerk: 25
	Technician: 4
	Freelance work: 9
	Unemployed: 7
	Control:
	Office clerk: 30
	Technician: 2
	Freelance work: 14
	Unemployed: 5
	Race: Not specified
	Education: Education level
	Intervention:
	Junior high school: 5
	Senior high school: 7
	College: 13
	Bachelor or above: 20
	Control:
	Junior high school: 3
	Senior high school: 4
	College: 11
	Bachelor or above: 27
	Family income:
	Income level (Yuan/month)
	Intervention
	1000–1999: 3
	2000–2999: 13
	3000–3999: 11
	4000–4999: 10
	≥5000: 8
	Control
	1000–1999: 2
	2000–2999: 12
	3000–3999: 12
	4000–4999: 7
	≥5000: 12
	Inclusion criteria:
	Primi‐pars at least 20 years of age, having a single pregnancy confirmed by ultrasound, over 20 weeks of gestation, willing to have a vaginal birth, a pre‐pregnancy BMI of 18.5–24.9 and understanding of the written Chinese language
	Exclusion criteria:
	(1) over 35 years of age; (2) had pregnancy complications such as cardiovascular, digestive, endocrine and reproductive system diseases; (3) had a multiple gestation; and (4) could not have a vaginal birth because of predisposing factors such as an abnormal pelvis, malposition, or uterine fibroids
Interventions	Intervention (sample size):
	Transtheoretical model (TTM) interviewing. Intervention women received three face‐to‐face interventions and three follow‐up phone calls which were developed based on the Transtheoretical Mode (TTM)
	Intervention group was also provided a Booklet of Health Management (BHM), which described the benefits and necessary of weight management, the dietary management (controlling food intake, meeting the nutrition needs during different pregnancy stages, keeping a balanced diet, preparing foods using portions from a food exchange) and included information on an exercise plan during pregnancy
	Duration of intervention was from at least 20th week of pregnancy until 42 days postpartum
	(n = 45)
	Control (sample size):
	At the first prenatal check, the investigator provided routine health education about the effects of excessive gestational weight on pregnancy outcomes and explained the pattern of ideal weekly gain and overall maternal weight gain based on participants' calculated BMI. The maternal health handbook was distributed as a medical record at the first prenatal check which recorded the weight of each prenatal visit, which was a routine prenatal care. Duration was from at least 20th week of pregnancy until 42 days postpartum. It was delivered by the investigator
	(n = 45)
	Training:
	Not specified
	Follow‐up:
	Participants in the intervention group were assessed to determine their readiness for change to control their gestational weight gain during each prenatal visit between 20 and 30 weeks by asking questions congruent with each stage. After 30 weeks, four phone calls were made at 32, 34, 36, and 38–41 weeks of gestation to promote and reinforce the intervention. Women were weighed at the postpartum visit at 42 days postpartum
Outcomes	Primary outcomes: None
	Secondary outcomes:
	Macrosomia
	Birth weight
	Timing of outcome assessment: 42 days postpartum
Notes	Study start date: July 2013
	Study end date: June 2014
	Time period: 11 months
	Study country: China
	Study limitations:
	This study was limited to participants at one tertiary hospital in Wuhan. The findings, however, may not be generalized to other populations in China as China is a very large country with regional cultural differences. The study period ended at 42 days postpartum which may be a limited time frame in which to promote postpartum weight management, especially because the Chinese tradition of “doing the month” is a time when food consumption for postpartum recovery is encouraged. Use of participants' self‐report of their weight to calculate BMI may have led to bias in the data. Lastly, another limitation is that data about the incidence of breast‐feeding was not collected and breastfeeding is associated with postpartum weight reduction
	BMI pre‐pregnancy:
	Intervention: 20.80 ± 1.58
	Control: 21.24 ± 1.69
	Funding source: Not specified
	Conflict of interest: None