Weight loss in pregnancy - is it safe? What should dietetic practice be? A systematic review.

Obesity is a significant public health concern and is likely to remain so for the foreseeable future. Maternal obesity and excess gestational weight gain (GWG) increases the risk of a number of pregnancy complications including gestational diabetes. As a result, there has been a renewed focus on weight gain management strategies for obese women during pregnancy. Controversies exist within the literature regarding the optimum amount of gestational weight a woman should gain with some studies suggesting that gestational weight loss (GWL) is appropriate among obese women. The aim of this review is to examine the association between pregnancy outcomes in obese women with gestational weight loss (GWL) compared to gestational weight gain (GWG) within the institute of medicine (IOM) guidelines and provide evidence-based guidance for dietetic practice. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement was followed for identification of studies. Five databases were reviewed in conjunction with hand-searching of reference lists and government websites. Quality assessment was conducted using the modified Newcastle-Ottawa Scale (NOS) and thematic analysis was employed for data extraction and synthesis. Eight retrospective cohort studies were included. GWL is associated with reduced risk of large for gestational age (LGA) births, caesarean section and macrosomia. Conversely, GWL is associated with an increased risk of birthing a small for gestational age (SGA) infant. At this stage, despite decreased odds of LGA, increased odds of SGA and a lack of information on preterm birth indicate that GWL should not be advocated in general for obese women.