Home and Community Care Digest
Methods: Data extraction was completed by four reviewers (each study independently reviewed by two individuals) using a standardized, piloted data extraction form. There were no discrepancies between reviewers in deciding which articles to include and the information extracted. Meta-analysis was conducted according to published guidelines and adjusted for bias (i.e., negative findings not published). A sensitivity analysis was performed to examine the effects of varying methodological quality and inclusion criteria.
Findings: The systematic review included 39 articles, of which 18 were included in the meta-analysis. Mothers who were obese before becoming pregnant had almost twice the odds of having a child with a neural tube defect compared with mothers of recommended BMI and overweight. Furthermore, o women, but not overweight women, were also much more likely to have pregnancy complicated by spina bifida, heart septal anomalies, and orofacial clefts. Both obese and overweight women had higher odds of having a pregnancy affected by a cardiovascular anomaly. The sensitivity analyses did not result in changes to the findings.
Conclusions: In general, prepregnancy obesity, but not maternal overweight, was strongly associated with an increased risk of most congenital abnormalities examined in the study. The authors suggest mechanisms for the observed association are: (i) undiagnosed diabetes, (ii) difficulty in ultrasound screening in obese women that results in fewer terminated pregnancies affected by congenital anomalies, and perhaps most importantly, (iii) nutritional deficiencies such as reduced folate intake. Awareness should be raised on the dangers to the unborn foetus associated with prepregnancy obesity, and obese women seeking to become pregnant should be counselled on weight loss strategies and improved nutrition to reduce the identified risk of congenital abnormalities.
Stothard KJ, Tennant P, Rankin J. Maternal overweight and obesity and the risk of congenital abnormalities: A systematic review and meta-analysis. JAMA, 2009; 301(6): 636-650.
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