The research was conducted in Britain by Katherine J. Stothard and colleagues from Newcastle University. It reviewed 39 articles and analyzed the data from 18 articles with the aim of finding how maternal overweight and obesity (body mass index greater than 30) influence the development of congenital anomalies.
"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 head due to accumulation of cerebrospinal fluid]; and a limb reduction anomaly," the scientists said.
About 3 percent of all live births in the United States exhibit such abnormalities. Some 0.68 per 1,000 births are affected by a neural tube defect and 2.25 per 1,000 births have a serious heart anomaly.
The researchers calculated the absolute risk for a pregnant obese woman to give birth to a baby with a neural tube defect or a serious heart anomaly respectively as 0.47 per 1,000 births and 0.61 per 1,000 births more than for a normal-weight pregnant woman.
"This has health implications, particularly given the continued rise in the prevalence of obesity in many countries," the authors said.