Pre-conception lifestyle intervention to optimise maternal health for a better start to life: the BEGIN BETTER...

Overweight and obesity impacts approximately 50% of pregnant women. Professional medical colleges worldwide recommend women with a higher body mass index (BMI) lose weight before conception. While diet and lifestyle interventions before pregnancy are associated with improvements in diet and modest weight loss, subsequent clinical pregnancy outcomes are poorly reported.Our aim is to conduct a randomised controlled trial of a comprehensive lifestyle intervention for women with overweight or obesity who are planning pregnancy. We will evaluate the impact of this intervention on maternal health and well-being prior to conception; and pregnancy, birth and newborn health outcomes in a subsequent pregnancy.

Women with a BMI ≥25.0 kg/m² who plan to conceive within 2 years will be recruited.Women randomised to the 'Educational Control Group' will attend a pre-conception health consultation with a research midwife, providing limited information about obesity and associated risks in pregnancy, nutrition, exercise and weight management.Women randomised to the 'Pre-pregnancy Lifestyle Intervention Group' will attend a pre-conception health consultation with a research midwife, as above, and additionally consult with a research dietitian and trained health coaches throughout the 6-month intervention period. Women will also have access to a specifically designed mHealth application providing tailored content and interactive tasks delivered bi-weekly during this time.

Secondary outcomes will include a range of maternal pre-conception health outcomes; maternal and infant pregnancy and birth outcomes; diet and physical activity changes; and quality of life.We estimate a mean birth weight z-score of 0.43 (SD 1.09) and will recruit 800 women to detect 0.4 SD difference (alpha 0.05 (two-tailed); power 80%). Analyses will be intention to treat with estimates reported as relative risks and 95% CIs.

The study protocol was approved by the Human Research and Ethics Committee of the Women's and Children's Hospital, Adelaide, South Australia (HREC/17/WCHN/177; 2020/HRE01445) on 17 August 2018. The first participant was recruited in June 2021, with recruitment anticipated through 2025. The study results will be disseminated in open-access international journals, scientific meetings and conferences with stakeholders.

ACTRN 12621000128897. This study has been registered at (https://www.anzctr.org.au/).