In this study, Molyneaux and colleagues found that obese women had significantly higher odds of experiencing depression during their pregnancy (antenatal depression) than normal weight women. However, this was not related to particular dietary patterns, or to inadequate or excessive weight gain during pregnancy.
The researchers found that rates of antenatal depression were lowest among women who were normal weight when they became pregnant, greater among overweight women and highest among obese women. This was still the case when the researchers took into account other factors that could explain the differences between the women, such as socio-demographic variables (e.g., age, marital status, education level) and health behaviours (e.g., smoking, alcohol consumption). Pre-pregnancy weight and antenatal depression did not interact to predict any particular dietary patterns (e.g., eating processed foods) and did not predict inadequate (less than recommended) or excessive (greater than recommended) weight gain during pregnancy (gestational weight gain).
Emma Molyneaux, Lucilla Poston, Mizanur Khondoker, & Louise M. Howard
King’s College London and University College London, United Kingdom
The researchers wanted to assess: i) the relationship between antenatal depression and high pre-pregnancy BMI (overweight or obesity); ii) whether, combined, these factors predict diet, or inadequate or excessive gestational weight gain.
The researchers highlight that many women are now obese when they become pregnant. Although the physical health risks are well established, less is known about the relationship between obesity and mental health during pregnancy. Mental health even has the potential to influence physical health and health behaviours during this important time.
The researchers used data from the Avon Longitudinal Study of Parents and Children (also known as ALSPAC or Children of the 90s). This study recruited pregnant women in the Bristol area in the early 1990s and has been charting the health of their families (approximately 14500 of them!) ever since. For this piece of research, Molyneaux and colleagues excluded women who were underweight and who had experienced pregnancy or neonatal loss, so data from 13314 women were included. The women had self-reported their pre-pregnancy height and weight (used to calculate BMI and classify them as normal weight, overweight or obese). They also completed a standard depression questionnaire and a food frequency questionnaire (to build a picture of their diet). Gestational weight gain measurements were collected from the women’s official pregnancy records.
ScientiFix tip: Most of the data in this study were self-reported by the women, so there is a possibility of measurement bias. For example, they may have underestimated their weight or overestimated their height. However, the authors indicate that self-reported BMI was highly correlated to the measurements taken formally at the women’s first antenatal appointments. The authors also acknowledge that it would be useful to replicate these findings in a more recent dataset, as these data were collected in the early 1990s. Nonetheless, the findings of this study have important implications. For instance, health care professionals who are in contact with pregnant women need to be aware of the increased risk of antenatal depression among those who are obese when they become pregnant, in order to better support them.