Study question: What are the pre-existing medical conditions and lifestyle behaviours of women with and without PCOS during the preconception period?

Summary answer: During the preconception period, medical conditions of obesity, depression, anxiety, and a history of infertility were more highly prevalent in women with than without PCOS, and more women with than without PCOS were engaged in unhealthy lifestyle behaviours.

What is known already: Women with PCOS are predisposed to infertility and pregnancy complications. Optimizing preconception medical health and lifestyle behaviours can improve maternal and pregnancy outcomes but, to the best of our knowledge, no study has examined the preconception medical conditions and lifestyle behaviours of women with PCOS.

Study design, size duration: This is a cross-sectional study on 942 women with PCOS and 7024 women without PCOS, aged 24-30 years from the Australian Longitudinal Study of Women's Health, an ongoing, national survey-based prospective cohort study.

Participants/materials, setting, methods: The current study analysed self-reported data from Survey 6 collected in 2019 of the cohort of women born between 1989 and 1995. Explored outcomes included BMI, pre-existing medical conditions, and modifiable lifestyle behaviours, including smoking, recreational drug use, alcohol intake, and physical activity level, during the preconception period. Differences between subgroups were tested using Student's t-test, χ2 test, or Fisher's exact test as appropriate. The associations of pregnancy intention with medical conditions and lifestyle behaviours were examined using logistic regression.

Main results and the role of chance: Obesity, depression, anxiety, and infertility were highly prevalent in women actively planning for pregnancy. Among women with PCOS, the prevalence of obesity was 47.02%, followed by depression at 32.70%, anxiety at 39.62%, and infertility at 47.17%. Conversely among women without PCOS, the corresponding prevalence was lower, at 22.33% for obesity, 18.98% for depression, 23.93% for anxiety, and 16.42% for infertility. In women actively planning for pregnancy, only those without PCOS demonstrated a lower prevalence of unhealthy lifestyle behaviours compared to non-planning women. The prevalence of unhealthy lifestyle behaviours was similar in women with PCOS regardless of their pregnancy intentions. Multivariable logistic regression revealed that only moderate/high stress with motherhood/children (adjusted odds ratio (OR) 3.31, 95% CI 1.60-6.85) and history of infertility (adjusted OR 9.67, 95% CI 5.02-18.64) were significantly associated with active pregnancy planning in women with PCOS.

Limitations, reasons for caution: The findings were based on self-reported data. The cohort of women surveyed may have a higher level of education than women in the community, therefore our findings may underestimate the true prevalence of pre-existing medical conditions and lifestyle challenges faced by the broader population.

Wider implications of the findings: A higher proportion of women with than without PCOS had pre-existing medical conditions and engaged in potentially modifiable unhealthy lifestyle behaviours during preconception despite their risk for subfertility and pregnancy complications. Healthcare professionals play a pivotal role in guiding this high-risk group of women during this period, offering counselling, education, and support for the adoption of healthy lifestyles to improve fertility, pregnancy outcomes, and intergenerational health.

Study funding/competing interest(s): C.T.T. holds a seed grant from the National Health and Medical Research Council (NHMRC) through the Centre of Research Excellence in Women's Health in Reproductive Life (CRE WHiRL) and Royal Australasian College of Physician Foundation Roger Bartop Research Establishment Fellowship. H.T. holds an NHMRC Medical Research Fellowship. C.L.H. holds an NHMRC CRE Health in Preconconception and Pregnancy Senior Postdoctoral Fellowship. A.E.J. holds a CRE WhiRL Early to Mid-career Fellowship. The authors have no conflicts of interest to declare.

Trial registration number: N/A.