For women who are obese during pregnancy there is an associated increased
risk of certain birth defects, such as spina bifida and neural tube defects,
although the absolute increase in risk is likely to be small, according to an
analysis of previous studies, reported in the February 11 issue of
Obesity is a major public health and economic concern. In the United States,
a third of women age 15 years and older were obese (body mass index [BMI]
greater than 30) in 2004. There are significant health implications of
prepregnancy maternal obesity for both mother and child. There is evidence that
suggests that maternal obesity may be associated with the development of some
congenital anomalies (abnormality present at birth). Congenital anomalies are a
leading cause of stillbirth and infant death, accounting for 1 in 5 infant
deaths in the United States, and are important contributors to preterm birth
and childhood illnesses, according to background information in the
Katherine J. Stothard, Ph.D., and colleagues from Newcastle University,
Newcastle upon Tyne, U.K., conducted a review and meta-analysis of studies to
assess the relationship between maternal overweight and obesity and the risk of
congenital anomaly in newborns. The researchers identified 39 articles that
were included in a systematic review and 18 articles in the meta-analysis.
"In women who were obese at the start of pregnancy, the meta-analysis
demonstrated a significantly increased risk of a pregnancy affected by a neural
tube defect [nearly twice the odds], including spina bifida [more than twice
the odds]; cardiovascular anomaly, including a septal anomaly [heart defect];
cleft palate and cleft lip and palate; anorectal atresia [abnormality of the
anus/rectum]; hydrocephaly [abnormal enlargement of the ventricles of the brain
due to accumulation of cerebrospinal fluid]; and a limb reduction
anomaly," the authors write.
The risk of gastroschisis (abdominal wall defect) among obese mothers was
"An estimated 3 percent of all livebirths in the United States are
affected by a structural anomaly with 0.68 per 1,000 births being affected by a
neural tube defect and 2.25 per 1,000 births being affected by a serious heart
anomaly. Given the findings of this review, and the BMI profile of the female
population during the period when these estimates were generated, we calculate
that the absolute risk of a pregnancy affected by a neural tube defect or a
serious heart anomaly is respectively 0.47 per 1,000 births and 0.61 per 1,000
births greater in an obese woman than a woman of recommended BMI in
prepregnancy or early pregnancy. This has health implications, particularly
given the continued rise in the prevalence of obesity in many countries,"
the authors write.
They add that further studies are needed to confirm whether maternal
overweight is also implicated.