Diet and exercise does not prevent gestational diabetes in obese women
A diet and exercise regime for high-risk obese pregnant women,
whilst effective in promoting a healthy lifestyle, does not prevent
gestational diabetes, finds a study led by King's College London.
The findings, published in the Lancet Diabetes and
Endocrinology, suggest that programmes promoting healthy
behaviours are unlikely to be effective in preventing gestational
diabetes in obese women; instead, resources should be directed
towards better screening and treatment, including the use of a more
stringent threshold for diagnosis.
Obesity rates are highest in developed countries, affecting 25%
of women in the UK and 34% of women in the US. Obesity is a risk
factor for complications in pregnancy, especially gestational
diabetes and large-for-gestational-age delivery (LGA). Previous
studies have suggested that lifestyle intervention programmes might
help reduce the risk of gestational diabetes in obese pregnant
women, but this is first large-scale trial to test the effect of an
intensive intervention in the UK and the world.
The randomised UPBEAT study, funded by the National Institute
for Health Research, recruited over 1,500 women from eight
inner-city antenatal services providing care to multi-ethnic
(including White, Black and Asian) populations of generally high
socioeconomic deprivation across the UK.
Half the women (772) were placed in a control group given
standard antenatal care and advice, whilst the other half (783)
were assigned to eight, weekly, health trainer-led sessions.
Participants were given a handbook with recommended foods, recipes
and physical activity along with a DVD of an exercise regime safe
for pregnancy, a pedometer and a log book for recording their
weekly goals. Exercise focused on increasing the amount of walking
at a moderate intensity, and the women were advised to adopt a
healthier diet by swapping carb-rich foods for those with a lower
glycaemic index and limiting saturated fat intake.
All the women took a standard oral glucose tolerance test, but
researchers used more stringent WHO-recommended criteria (also
known as IADSPG criteria) to diagnose gestational diabetes and
implement treatment accordingly.
Overall, 332 (26%) of all participants were diagnosed with
gestational diabetes, but the study found no significant difference
between the standard and intervention groups. LGA infants made up
9% of the whole trial cohort, but no difference was observed
between standard and intervention groups.
However, the intervention led to other changes in the
intervention group such a lower glycaemic load and fat intake along
with higher levels of activity which were associated with
reductions in pregnancy weight gain (average weight was one pound
or half a kilo lower in intervention group) and reduced adiposity
Furthermore, researchers predicted that 17% of children would be
LGA, but found levels to be closer to normal population levels
(typically around 10%) which they believe to be due to the greater
number of women diagnosed and treated for gestational diabetes
using the WHO guidelines.
Professor Lucilla Poston, lead author from the Division of
Women's Health at King's College London, says: 'Our study shows
that an intensive diet and exercise regime alone cannot help reduce
the risk of developing gestational diabetes in obese women.
'However, using a more stringent diagnostic test for gestational
diabetes meant we picked up more cases. We believe the greater
number of women treated as a result of this test may explain why
our study found a lower than anticipated incidence of LGA infants
in all women. This has implications for the diagnosis of
gestational diabetes in the UK as NICE have recently decided
against adoption of the WHO (IADPSG) criteria.
'Whilst the intervention did not prevent gestational diabetes,
the UPBEAT study provides a new and effective strategy to improve
diet and physical activity in obese pregnant women adoptable in a
UK healthcare setting. We are now following the mothers and
children from this cohort to see whether changes in the mothers'
diet and activity are sustained and have an effect on their health
and that of their offspring.'