Introduction
The World Health Organization defines obesity as a body mass index
(BMI) of 30
kg/m2 or more (1). Worldwide, over one third of women
of reproductive age are now obese (2).
In the United States, the reported
prevalence of obesity in women of reproductive age between 1999-2002 was
29% (3). More than a decade later this prevalence had risen to 38%
(4). United Kingdom, has a reported prevalence of obesity in in women of
reproductive age of 10.9% (5), Australia of 28% (6) and Asia of 22%
(7).
At the same time, the reported
prevalence of gestational diabetes mellitus (GDM) in Europe varies
considerably, and in certain populations is reported to occur in more
than 20% of pregnancies (8-10)
raising to as high as 52% in women with a BMI ≥
29kg/m2 (11).
With such high and rising
prevalence, obesity and GDM have become the most common clinical risks
in obstetric practice increasing the probability of a variety of
pregnancy-related complications compared to women with a normal BMI and
normal glucose tolerance(5, 12-16).
Beyond the impact of a high
baseline BMI on pregnancy outcomes, the amount of weight gained during
pregnancy can affect the immediate and future health of a woman and her
infant. The Institute of Medicine (IOM) guidelines for weight gain in
pregnancy recommend weight gain of 5-9kg for all obese women (17).
Suboptimal gestational weight gain
(GWG), either excessive or
inadequate, is also associated with reported maternal and neonatal
complications (18-20). Current research indicates that excessive GWG and
high pre-pregnancy BMI are associated with increased risks for adverse
pregnancy outcomes (19, 21).
Thus, the question remains whether
more stringent recommendations for weight gain may improve GDM related
outcomes, by reducing the additive effect of diabetes, obesity and
excessive weight gain.
Recent studies have shown that in GDM women, minimal GWG led to higher
rates of small for gestational age infants (SGA)(18). However, a study
of overweight and obese GDM Asian women reported that minimal GWG and
tight blood glucose control during pregnancy may eliminate most of the
adverse pregnancy outcomes experienced (22).
The primary aim of this study was
to investigate the effects of GWG below the IOM recommendation on
pregnancy outcomes in women with GDM and a BMI ≥30
kg/m2.
As a secondary aim, we compared pregnancy outcomes in obese GDM women
with insufficient GWG, the IOM recommended GWG and excessive GWG.