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Central Coast Local Health District
Project Added:
20 November 2013
Last updated:
8 October 2014


Group antenatal care for obese pregnant women: Impact on weight gain in pregnancy

By Lyndall Mollart, Central Coast Local Health District


To compare the results of limiting weight gain in pregnancy to recommended levels (5-9kg) and the perinatal outcomes between the interdisciplinary model of the group antenatal care (POWERInG) and routine midwifery care for obese women.


Maternal obesity is a significant risk factor for adverse outcomes during pregnancy and childbirth. A one year retrospective audit of all women presenting to maternity services in two Local Health Districts (LHDs) in NSW identified that 24% of pregnant women were overweight (Body Mass Index - BMI 25-29.9) and 17% obese (BMI ≥ 30/m2). Limiting weight gain in pregnancy can improve pregnancy and birth outcomes for this group.

A specifically designed model to address this issue was developed and implemented as an initiative of the NSW Ministry of Health using a cost neutral, collaborative approach.


In 2010, a collaborative, interdisciplinary model of group antenatal care was successfully developed and implemented at Central Coast LHD (POWERInG: Pregnant Obese Women Engaging Resources In Groups) and South Eastern Sydney LHD (SSWInG: St George and Sutherland Weight Intervention Groups). 

As there are currently no specific guidelines for gestational weight gain in NSW, the US Institute of Medicine (IOM 2009) guidelines were used as recommendations for women accessing the program in both LHDs (i.e. 5-9kgs total weight gain in pregnancy with BMI Obese 30kg/m2).

The model consists of 8 x 2 hour sessions with a focus on:

  • Group based antenatal care and assessment
  • Education on healthy eating / physical activity in pregnancy
  • Setting of weight management goals / motivational techniques
  • Peer support and encouragement

The outcomes for the women in the SSWInG/POWERInG implementation evaluation suggested a positive benefit of group based antenatal care with focus on limiting weight gain.

At Central Coast LHD, an additional comparison was suggested to determine the difference between POWERInG group antenatal care and 'traditional' midwifery care at Central Coast LHD in relation to weight gain and perinatal outcomes. An additional audit was then conducted.


The audit was undertaken over a 12 month period (1 June 2010 - 30 May 2011) on women with a pre-pregnant BMI ≥ 30kg/m2 who chose to attend POWERInG (n=39) and those women who declined the model and attended routine midwifery care (n=74) at Wyong Hospital site.

The main reasons women gave for declining POWERInG were:

  • time constraints
  • lack of child minding
  • unable to attend on POWERInG day.

The audit included:

  • ObstetriX database: for pre-pregnant weight, BMI and Obstetric outcomes.
    • POWERInG (n=39)
    • Routine care (n= 74)
  • Admission weight to Birthing Suite (woman's medical record):
    • POWERInG (n=39)
    • Routine (n=57)
    • Data unavailable for 17 women.


  • There were more primiparas (43%) attending POWERInG than Routine midwife care (28%)
  • The mean BMI for women attending POWERInG was 38.3 (BMI range 30-61, Standard Deviation (SD) 6.2) and Routine care was 35.9 (BMI range 30-51, SD 4.4)
  • The percentage of women with a BMI ≥ 40kg/m2 (obesity class 3) accounted for 33% of POWERInG women compared to 14.8% attending Routine care as shown in Graph 1.

Powering BMI Class 30-34.9=30.8%, 35-39.9=35.9%, 40+=33.3%. Routine BMI class: 30-34.9=51.4%, 35-39.9=33.8%, 40+=14.8%
Graph 1 - BMI Class Comparison

Weight Gain

The aim of POWERInG is to assist obese women to limit their weight gain in pregnancy to recommended level (5-9kgs). As shown in Table 1, this aim was achieved with the average weight gain of 8.6kg (SD 8.3) compared to women attending Routine care was 13.5kgs (SD 7.9).

  Average Standard Deviation Average Standard Deviation
  POWERInG (n=39) ROUTINE CARE (n=57)
# Pre-pregnant weight 103.3 18.2 97.5 14.5
Weight at birthing 112 17 112.2 15.2
Weight gain 8.6 8.3 13.5 7.9

Table 1 - Weight Gain

Obstetric outcomes

  • Medical induction occurred for 63% women attending POWERInG (n=14/22) and 43% having Routine care (43% n=19/44). The most common reason for induction was for post-term pregnancy (43% and 23% respectively)
  • Mode of Birthing: refer to Graph 2

Graph 1 Mode of birthing, POWERIng and Routine comparison.
Graph 2 - Mode of Birth Comparison

POWERIng: NVB=38.5%, Instum=18%, Elective C/S= 25.6%, Emergency C/S= 18%. Routing: NVB=43.2%, Instum=16.2%, Elective C/S=31.1%, Emergency C/S=9.5%

  • Postpartum haemorrhage 1000mls: There was no increase in significant PPH in either group (one woman in Routine care)
  • Neonatal birth weights: very similar in both models of care with average weight of 3670g (SD 602g) for POWERInG babies and 3672g (SD 505.3) for Routine care
  • Infant Feeding: Initiation of exclusive breastfeeding was higher with POWERInG group (92%, n=35/38) compared to Routine care (70%, 52/74) as shown in Graph 3.

Graph 3. Infant feeding POWERIng and Routine comaprision
Graph 3 - Infant Feeding Comparison

POWERIng: breast 92.1%, artifical 5.3%, combined 2.6%. Routine: breast 70.3%, artificial 12.2%, combined 17.6%.

Women's comments

Overall, women were extremely positive about having group antenatal care. The sharing of experiences was found to be both supportive and motivating:

"It helped to know what other mums were going through. The group helped to encourage me to keep healthy” and “Now I am motivated to get even healthier".

The women appreciated the opportunity to be involved in this new model of care and want to share their experience with others, want this care again with their next baby, and believe the service should be made more widely available:

"fantastic initiative and should be available to every pregnant woman".


The participants represented a cohort of women who chose to participate in this model of care and may have been more motivated to limit weight gain. There was no controlled comparison group to determine whether the weight gain occurred simply by chance. The initial weight recorded was also a self-reported pre-pregnancy weight which may limit benchmark accuracy.


Existing models of antenatal care have not been demonstrated to meet the needs of overweight and obese women. Group antenatal care with a focus on facilitated group discussions on pregnancy, labour and birth, healthy eating and increasing physical activity with peer support and networking opportunities has been effective in limiting the weight gain for these women. Although there was no overall difference in obstetric outcomes, there was a higher initiation of exclusive breastfeeding in the women attending POWERInG.

A collaborative, interdisciplinary antenatal program targeting the needs of overweight and obese pregnant women can be developed, implemented and sustained within our public health services.


Women who participated in this innovative new service had high levels of satisfaction with the service and particularly enjoyed the support and friendships that the group provided to assist them in limiting their weight gain. Group based antenatal care for obese women can be an efficient and effective means of providing targeted services to these women.


Cathy Adams, Maralyn Foureur, Deborah Davis, Vanessa Clements, Jane Raymond, Ali Teate


Clinical Midwifery Consultant - Antenatal Services
Maternity Services, Central Coast Kids & Families
Central Coast Local Health District
Phone: 02 4320 2461

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