What’s the best way to lose weight before pregnancy?

6 minute read

A world-first clinical trial called PreBabe aims to find out.

More than half of Australian women have overweight or obesity before conception, which has an impact on both the mother’s and the child’s health.

The mother is at risk of gestational diabetes, hypertension and other delivery complications. The babies have higher risks of stillbirth, preterm birth and – over their lifetime – obesity, cardiovascular disease and diabetes. [7-9]

Mothers with obesity have a 22% increase in antenatal hospital stays of two days or more, a 15% increase in caesarean section, a 29% increase in gestational diabetes mellitus and a 36% increase in pre-eclampsia. [10] They are less likely to lose weight after birth, and more likely to have overweight or obesity in a future pregnancy [11] and develop long-term cardiovascular disease. [6]

Studies minimising weight gain during pregnancy have had limited success in improving perinatal outcomes. The 2016 WHO Ending Childhood obesity report highlighted preconception and pregnancy care as one of six preventative recommendations for women with overweight and obesity. [12]

The Australian Council of Presidents of Medical Colleges has preconception planning in its six-point plan to stem the obesity pandemic [13].  Current literature recognises that preconception weight and health should be targeted before pregnancy to break the obesity cycle.

The PreBabe study is a world-first clinical trial sponsored by the University of Sydney. It will explore how losing weight before pregnancy might improve the long-term health of mothers and babies.

The study aims to determine whether a partial meal replacement program compared with usual care and dietary recommendations will improve perinatal outcomes. The primary outcomes are: a combination of gestational diabetes or pre-eclampsia or first caesarean section in the mother; and perinatal death or birth weight above the 90th centile or admission to the neonatal unit in the baby. Secondary outcomes will assess other perinatal, obstetric and maternal outcomes.

Losing weight before trying to get pregnant may make it easier to conceive. [14]

Women in NSW with overweight or obesity (BMI > 25), aged 18 to 40 and planning a pregnancy are invited to join the PreBabe Trial.

We are looking for 1927 women to take part over the next two and a half years. All women can participate in the trial via telehealth appointments and women who are in Sydney or Newcastle can choose to attend a study site in person for two visits if they wish.

The site teams are located in five sites: Royal Prince Alfred Hospital, Camperdown; Royal Hospital for Women, Randwick; Nepean Hospital, Kingswood; Westmead Hospital, Westmead; and John Hunter Hospital, Newcastle.

Many GPs provide preconception care and advice and are critically important members of a women’s healthcare team.

You can encourage women to visit our website for more info at www.prebabe.com.au. Participating women will be offered a free 10-week weight loss program as part of the trial.

The PreBabe study is testing two different approaches to losing weight prior to pregnancy to see which has the best short- and long-term results for women and babies.

Approach 1 is a combination of meal replacements and conventional healthy meals supported by a trial website.

Approach 2 involves conventional healthy meals supported by telephone coaching calls.

Both weight loss programs are supported by a clinical team, have a non-judgmental and positive health focus and are designed to be followed for 10 weeks prior to trying to get pregnant.

While there are many ways to safely lose weight, this study is testing two different approaches to losing weight before pregnancy, to see which is best for women and babies long-term. Both approaches are safe and designed for use before becoming pregnant.

If women become pregnant while on the study, we will help them move safely to a healthy pregnancy eating plan.

The study will help to find out which weight loss approach is better for women living in larger bodies who want to become pregnant. The results will provide better information for women in future when making decisions about how to have a safe healthy pregnancy, and birth, and which type of weight loss has the best short- and long-term results.

What is involved for those wanting to take part?

  • Study participants will be allocated to one of the two weight loss programs, each of which runs for 10 weeks.
  • Women can join virtually or in person.
  • Every woman will then be contacted monthly over the next 12 months to ask if they have become pregnant.
  • Participants will not be paid for taking part but will have the opportunity to be part of a free 10-week weight loss program.

Scan the QR code below to find out more:

Adrienne Gordon is Clinical Professor, Discipline of Obstetrics, Gynaecology and Neonatology at the  Faculty of Medicine and Health, University of Sydney. She is also Co-Chair at the Sydney Institute for Women, Children and their Families and a Senior Staff Specialist Neonatologist


  1. Australian Institute of Health and Welfare 2019. Australia’s mothers and babies 2017—in brief. Perinatal statistics series no. 35. Cat. no. PER 100. Canberra: AIHW
  2. McIntyre, H.D., et al., Overweight and obesity in Australian mothers: epidemic or endemic? Medical Journal of Australia, 2012. 196(3): p. 184-8.
  3. Catalano, P.M., et al., The hyperglycemia and adverse pregnancy outcome study: associations of GDM and obesity with pregnancy outcomes. Diabetes Care, 2012. 35(4): p. 780-6.
  4. Bider-Canfield, Z., et al., Maternal obesity, gestational diabetes, breastfeeding and childhood overweight at age 2 years. Pediatric Obesity, 2017. 12(2): p. 171-178.
  5. Buchanan, T.A., A.H. Xiang, and K.A. Page, Gestational diabetes mellitus: risks and management during and after pregnancy. Nat Rev Endocrinol, 2012. 8(11): p. 639-49.
  6. Appiah, D., et al., Association of Gestational Diabetes Mellitus With Left Ventricular Structure and Function: The CARDIA Study. Diabetes Care, 2016. 39(3): p. 400-7.
  7. Hayes, A.J., et al., Modelling obesity trends in Australia: unravelling the past and predicting the future. Int J Obes (Lond), 2017. 41(1): p. 178-185.
  8. Hayes, A., et al., Early childhood obesity: Association with healthcare expenditure in Australia. Obesity (Silver Spring), 2016. 24(8): p. 1752-8.
  9. Colagiuri, S., et al., The cost of overweight and obesity in Australia. Med J Aust. , 2010. 192(5): p. 260 – 264.
  10. Yang, Z., et al., Contribution of maternal overweight and obesity to the occurrence of adverse pregnancy outcomes. Aust N Z J Obstet Gynaecol, 2019. 59(3): p. 367-374.
  11. Mannan, M., et al., Association between weight gain during pregnancy and postpartum weight retention and obesity: a bias-adjusted meta-analysis. Nutrition Reviews, 2013. 71(6): p. 343-52.
  12. Swinburn, B. and S. Vandevijvere, WHO report on ending childhood obesity echoes earlier recommendations. Public Health Nutr, 2016. 19(1): p. 1-2.
  13. Talley, N., National Health Summit on Obesity calls for Australia to take action to stem the pandemic. MJA, 2017. 206(3).
  14. Muirhead R et al. A Pilot Randomized Controlled Trial of a Partial Meal Replacement Preconception Weight Loss Program for Women with Overweight and Obesity. Nutrients. 2021 Sep 15;13(9):3200

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