2009-02-09 10:12:32
A new study has underlined the high risks faced by obese women in their first
pregnancy.
Scientists at Kings College in London analysed data from the pregnancies of 385
first-time obese mothers.
They found that obese women had higher rates of eclampsia and premature births
compared to women inside recommended weight guidelines.
Obese women were nearly twice as likely to give birth to a low-weight baby,
weighing less than 5lbs 8oz (2.5kg).
Experts say it is a huge issue for all maternity units in the UK.
The researchers, who report their findings of the American Journal of
Obstetrics and Gynaecology study, also took blood samples taken from 208 of the
women for further analysis.
High risks
At birth, 18.8% of their babies were classified as having a low birth weight -
they weighed less than 2.5kg.
This compares with 10% of babies born to women of prescribed weight - known as
the "healthy population".
Babies who were deemed to be of a particularly large weight made up 13.4% of
those born to the women studied, compared to 10% in a healthy population.
Rates of pre-eclampsia were higher, with 11.7% of obese first-time mothers
developing the condition compared to 6% of obese women with one or more
previous pregnancies and 2% of the healthy population.
The risk of pre-eclampsia increased according to how much weight the women put
on in pregnancy.
Premature births were almost twice the national average at 11.9%.
The lead researcher, Professor Lucilla Poston of Kings College Hospital and St
Thomas's Hospital, said: "The large proportion of small babies was particularly
unexpected as obesity is more often associated with the birth of overweight
babies.
"The high number of cases of pre-eclampsia found in this group was very
concerning as this is a serious pregnancy complication which, in extreme cases,
can result in maternal and/or foetal death.
"We must now start to consider first-time pregnancy as an additional problem in
obese pregnant women, who we know are already more likely than thinner women to
have a complicated pregnancy."
The risks associated with prematurity and low birth weight include brain
damage, difficulty with breathing, learning problems and greater susceptibility
to infection.
Professor Postin said the reason why obesity causes these problems is not known
but it's believed that insulin resistance may be the problem.
Insulin resistance is when normal amounts of insulin can't completely breakdown
sugar in the diet.
" Normal pregnancy induces a mild form of insulin resistance and we know that
obese people become more insulin resistant and that promotes diabetes,
pre-eclampsia and macrosomia or bigger babies."
Increasing burden
The researchers say the women in the study had a high rate of Caesarean
sections and warn that increasing numbers of obese pregnancies could make a
major contribution to the rise in the number of caesareans in the UK.
They also point out that the women stayed longer in hospital, 4.6 days compared
to a national average of three days or fewer.
Professor Jane Norman, professor of maternal and foetal health at the
University of Edinburgh, said: "This study underlines and emphasises the
pregnancy risks for obese women.
"It shows that women in their first pregnancy run a particularly high risk and
that the issue about obese women is not just their weight before pregnancy but
how much weight they gain during it.
"Obstetricians are just starting to wake up to this.
"Previously their concerns were twin pregnancies, diabetic mums and older
women."
Professor Norman has set up a clinic for obese pregnant women at the Royal
Infirmary in Edinburgh.
There are only two such clinics in the UK.
They try to encourage obese women not to gain too much weight during pregnancy.
Professor Norman said the extra costs of treating them were not just down to a
longer stay in hospital: "We've had to buy in lots of new equipment in order to
treat obese people properly.
"New operating tables and even new blood pressure cuffs because the ordinary
ones give wrong readings on an obese person.
"This is a huge issue for all maternity units including our own."
Mervi Jokinen, from the Royal College of Midwives, said: "Obesity is an issue
that is becoming increasingly prominent in maternity care and midwives are
aware of the complexities and potential problems that obesity brings into
pregnancy.
"We need to ensure that women get early access to a midwife so that she can get
lifestyle and weight management advice as soon as possible, and that this
continues throughout the pregnancy and after the birth of the baby.
"This survey also reinforces the need to tackle obesity not just as an issue
for maternity services but as a much wider public health issue, because this is
a health problem that affects men as well as women and children as well as
adults."