Background Maternal overweight and obesity prevalence is rising globally. In the UK, approximately 1 in 5 women attending antenatal care have obesity. The risks and consequences of maternal overweight and obesity are well known, including increased risk of maternal mortality and pre-term birth. However, the topic of weight is highly stigmatised; thus, how pregnant and postpartum women manage weight during and after pregnancy remains poorly understood. Publicly available online forums provide a unique opportunity to gather ‘unfiltered’ and diverse views on a given topic. This study aimed to explore the experiences and perceptions of weight and weight-related behaviours in pregnant and postpartum women with overweight or obesity through analysing posts on a widely used online forum (Mumsnet).

Methods Using a qualitative design, we adapted an existing method of analysing textual data on Mumsnet. Data generated between July 2021 and March 2022 were extracted using the web scraping tool Parsehub. We applied a priori inclusion and exclusion criteria to screen and identify posts for inclusion in the analysis. Specifically, posts suggestive of overweight/obesity (e.g., BMI, weight/height mentioned) and posts related to diet and physical activity were eligible for inclusion. We analysed data using thematic and content analysis, following established methods.

Results Of 3,124 replies extracted from the Mumsnet Talk forum, 113 met the inclusion criteria and were included in the analysis. We identified six themes from the data analysis: ‘concerns surrounding overweight pregnancy’, ‘impacts of pregnancy on eating and physical activity behaviour’, ‘experiences and attitudes concerning weight change and management during the perinatal period’, ‘self-esteem during and after pregnancy’, ‘postpartum diet and personal struggles with weight’ and ‘healthcare professionals’ impact on women’. Women discussed their weight management goals throughout the perinatal period, specifically weight loss and maintenance. Concerns around overweight and obesity during the perinatal period resulted in self-directed research online, as women reported these concerns being left unaddressed by healthcare professionals.

Discussion The forum enabled women to share their personal experiences, revealing varied weight-related behaviours and attitudes, some of which contradict current medical guidelines, such as aiming to lose weight during pregnancy. Many women reported using self-directed approaches to weight management during and after pregnancy, drawing on a variety of resources and support. Implications for future research and practice include: exploration of misinformation and the effectiveness of strategies to mitigate this (e.g., forum moderation); development of support/services that support safe weight management during pregnancy and postpartum.