Preconception care and the risk of congenital anomalies in the offspring of women with diabetes mellitus: a meta-analysis

Offspring of women with pregestational diabetes mellitus are at increased r isk for congenital malformations, largely attributable to poor periconcepti onal glycaemic control. We assessed the effect of preconception care in red ucing congenital malformations, in a meta-analysis of published studies of preconception care in women with diabetes mellitus. Articles were retrieved from Medline (1970 to June 2000) and Embase (1980 to June 2000), and data abstracted by two independent reviewers. The rates and relative risks (RR) for major and minor congenital malformations were pooled from all eligible studies using a random effects model, as were early first-trimester glycosy lated haemoglobin values. In 14 cohort studies, major congenital malformati ons were assessed among 1192 offspring of mothers who had received preconce ption care, and 1459 offspring of women who had not. The pooled rate of maj or anomalies was lower among preconception care recipients (2.1 %) than non -recipients (6.5 %) (RR 0.36, 95%Cl 0.22-0.59). In nine studies, the risk f or major and minor anomalies was also lower among women who received precon ception care (RR 0.32, 95%Cl 0.17-0.59), as were the early first-trimester mean glycosylated haemoglobin values (pooled mean difference: 2.3%, 95%Cl 2 .1-2.4). Women who received preconception care were, on average, 1.8 years older than nonrecipients, and fewer smoked (19.6% vs. 30.2%). Only one stud y described the routine use of peri-conception folic acid. Out-patient prec onception care probably reduces the risk of major congenital anomalies amon g the offspring of women with pregestational diabetes mellitus. Because man y women with diabetes neither plan their pregnancy nor achieve adequate gly caemic control before conception, strategies are needed to improve access t o these programs, and to maximize those interventions associated with impro ved pregnancy outcome, such as smoking cessation and folic acid use.