Gestational diabetes is a typical example of a term with a strong nocebo effect. It has the power to transform a happy pregnant woman into an anxious or depressed one … One of the side effects of the term ‘gestational diabetes’ is to transform the interpretation of the results of a test into a disease. The status of disease implies that complications have been identified. It is commonplace to claim that macrosomia (a big baby) is the main complication. This should be considered an association. It is obvious that the energy requirements of a big baby are not the same as the requirements of a small one: the mother, who must make a bigger effort than others, is labelled as having ‘gestational diabetes’ … The nocebo effect of the term ‘gestational diabetes’ is becoming a serious issue. The use of enlarged criteria to interpret the tests is one of the reasons why the number of women diagnosed with gestational diabetes is increasing” (Odent 2013: 100-102).
Also, for anyone who missed it, the Cochrane Collaboration published an update on their review of the research on screening for gestational diabetes a few weeks ago. The review concluded that there was insufficient evidence to determine if screening for gestational diabetes, or what types of screening, can improve maternal and infant health outcomes (Tieu et al 2014; abstract below).
Screening and subsequent management for gestational diabetes for improving maternal and infant health
Objectives: To assess the effects of different methods of screening for GDM and maternal and infant outcomes.
Search methods: We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register (1 December 2013).
Selection criteria: Randomised and quasi-randomised trials evaluating the effects of different methods of screening for GDM.
Data collection and analysis: Two review authors independently conducted data extraction and quality assessment. We resolved disagreements through discussion or through a third author.
Main results: We included four trials involving 3972 women in the review. One quasi-randomised trial compared risk factor screening with universal or routine screening by 50 g oral glucose challenge testing. Women in the universal screening group were more likely to be diagnosed with GDM (one trial, 3152 women, risk ratio (RR) 0.44, 95% confidence interval (CI) 0.26 to 0.75). This trial did not report on the other primary outcomes of the review (positive screen for GDM, mode of birth, large-for-gestational age, or macrosomia). Considering secondary outcomes, infants of mothers in the risk factor screening group were born marginally earlier than infants of mothers in the routine screening group (one trial, 3152 women, mean difference (MD) -0.15 weeks, 95% CI -0.27 to -0.03).
The remaining three trials evaluated different methods of administering a 50 g glucose load. Two small trials compared glucose monomer with glucose polymer testing, with one of these trials including a candy bar group. One trial compared a glucose solution with food. No differences in diagnosis of GDM were found between each comparison. However, in one trial significantly more women in the glucose monomer group screened positive for GDM than women in the candy bar group (80 women, RR 3.49, 95% CI 1.05 to 11.57). The three trials did not report on the primary review outcomes of mode of birth, large-for-gestational age or macrosomia. Overall, women drinking the glucose monomer experienced fewer side effects from testing than women drinking the glucose polymer (two trials, 151 women, RR 2.80, 95% CI 1.10 to 7.13). However, we observed substantial heterogeneity between the trials for this result (I² = 61%).
Authors’ conclusions:There was insufficient evidence to determine if screening for gestational diabetes, or what types of screening, can improve maternal and infant health outcomes.
Odent M (2013). Childbirth and the future of homo sapiens. Pinter and Martin, London.
Tieu J, McPhee AJ, Crowther CA, Middleton P. Screening and subsequent management for gestational diabetes for improving maternal and infant health. Cochrane Database of Systematic Reviews 2014, Issue 2. Art. No.: CD007222. DOI: 10.1002/14651858.CD007222.pub3.