Strengths and limitations
Our study is not without limitations. This is a retrospective
convenience sample and prone to confounding bias, while every effort was
made to control for potential confounding factors by implementing
multivariable logistic regression analyses to estimate the association
between gestational weight loss and pregnancy outcomes, there may be
residual variables for which we did not have information. Furthermore,
given the study design, we acknowledge that some outcomes are
underpowered and that a higher number of study participants might reveal
stronger associations.
Another study limitation is the procedure for assessment of patient’s
weight. At our centres, equipment is calibrated on a regular basis. Due
to the retrospective nature of the study it is difficult to guarantee
the standardisation of the weighing process.
Moreover, we do not know the reasons for weight loss in this population.
It is possible that some women lost weight because of factors that
placed them at risk of adverse outcomes, but we are unable to fully
explore this. We assumed that women who lost/gained insufficient weight
likely made lifestyle changes subsequent to their GDM diagnosis. We
acknowledge that further investigation is required to clarify the
reasons for weight loss in this population. In addition, due to the
observational nature of this data, we cannot state a causal relationship
between gestational weight loss and adverse outcomes. Since it is not
possible to perform a randomized controlled study of weight
loss/insufficient GWG versus adequate GWG (as recommended by the IOM),
we believe that the current analysis provides valuable information that
may be useful in caring for this high-risk population.
Lastly, we used HbA1c as a measure of glycemic control as individual
readings were recorded in a paper-based diary retained by the study
participant and thus not available to the research team.