High maternal iron status, dietary iron intake and iron supplement use in pregnancy and risk of gestational diabetes mellitus: a prospective study and systematic review

AIM

High iron measured using dietary intake and biomarkers is associated with Type 2 diabetes. It is uncertain whether a similar association exists for gestational diabetes mellitus. The aim of this systematic review was to conduct a cohort study examining first trimester body iron stores and subsequent risk of gestational diabetes, and to include these findings in a systematic review of all studies examining the association between maternal iron status, iron intake (dietary and supplemental) and the risk of gestational diabetes.

METHODS

Serum samples from women with first trimester screening were linked to birth and hospital records for data on maternal characteristics and gestational diabetes diagnosis. Blood was analysed for ferritin, soluble transferrin receptor and C-reactive protein. Associations between iron biomarkers and gestational diabetes were assessed using multivariate logistic regression. A systematic review and meta-analysis, registered with PROSPERO (CRD42014013663) included studies of all designs published in English from January 1995 to July 2015 that examined the association between iron and gestational diabetes and included an appropriate comparison group.

RESULTS

Of 3776 women, 3.4% subsequently developed gestational diabetes. Adjusted analyses found increased odds of gestational diabetes for ferritin (OR 1.41; 95% CI 1.11, 1.78), but not for soluble transferrin receptor (OR 1.00; 95% CI 0.97, 1.03) per unit increase of the biomarker. Two trials of iron supplementation found no association with gestational diabetes. Increased risk of gestational diabetes was associated with higher levels of ferritin and serum iron and dietary haem iron intakes.

CONCLUSIONS

Increased risk of gestational diabetes among women with high serum ferritin and iron levels and dietary haem iron intakes warrants further investigation.

Occurrence and recurrence of diabetes in pregnancy

AIMS

To determine occurrence and recurrence rates of gestational diabetes among women having at least two consecutive pregnancies. Risk factors for recurrence of gestational diabetes and rates of second/third pregnancy pre-existing diabetes mellitus were also assessed.

METHODS

Population-based study using longitudinally linked hospital discharge and birth records (2001-2009) in NSW, Australia. Participants included women without a pre-existing diagnosis of Type 1 or Type 2 diabetes at time of first pregnancy and with at least a first and second birth. Factors associated with recurrence of gestational diabetes were examined using multivariate log-binomial models to adjust for correlation within mothers and estimate relative risks and 95% confidence intervals.

RESULTS

First occurrence of gestational diabetes was 3.7% (5315/142 843) in the first pregnancy and 2.7% (3689/137 528) in the second pregnancy. The recurrence rate of gestational diabetes in a second consecutive pregnancy was 41.2%. Risk of pre-existing diabetes in a pregnancy subsequent to one with first occurrence of gestational diabetes was 2.2% and 2.0% in the second or third pregnancy, respectively. Among women with a diagnosis of gestational diabetes in the first pregnancy, independent predictors of gestational diabetes recurrence were maternal age ≥ 35 years, ethnicity (Middle East/North Africa and Asia), pregnancy hypertension, large for gestational age infant and preterm birth in the first pregnancy, longer inter-pregnancy birth interval and pregnancy hypertension and multiple pregnancy in the second pregnancy.

CONCLUSIONS

Gestational diabetes in a previous pregnancy is a strong indicator of future risk and a useful clinical marker for identifying women at elevated risk in a subsequent pregnancy.

First trimester screening of maternal placental protein 13 for predicting preeclampsia and small for gestational age: in-house study and systematic review

OBJECTIVE

To describe normative levels of PP13 in first trimester of pregnancy and determine the accuracy of PP13 in predicting preeclampsia and small for gestational age (SGA) infants.

METHODS

We measured PP13 in archived first trimester serum samples from an unselected maternal cohort of 2989 women. Associations of PP13 levels and diagnostic accuracy in predicting adverse pregnancy outcomes were assessed using multivariate logistic regression models. Due to inadequate number of cases we then conducted a systematic review and subsequent meta-analysis of predictive accuracy. Structured searches including all languages were completed in electronic databases and supplemented by cross-checking reference lists of relevant publications. Characteristics, data extraction and quality assessment of studies was conducted by independent assessors.

RESULTS

Overall, 2678 women were included in the in-house study with 71 (2.7%) preeclampsia cases, 5 (0.2%) early-onset preeclampsia (≤34 weeks) cases; and 191 (7.1%) and 41 (1.5%) infants SGA<10th and <3rd centile. Median (IQR) normative level of PP13 in unaffected pregnancies was 53.5 (37.7-71.8) pg/ml. The area under the receiver operating characteristic curve (AUC) for multivariate models was 0.72 (95%CI 0.66-0.78) for preeclampsia; 0.82 (95%CI 0.63-0.99) for early-onset preeclampsia; 0.73 (95%CI 0.69-0.77) for SGA<10th centile; and 0.83 (95%CI 0.78-0.88) for SGA<3rd centile. Eight studies were included in the systematic review, normative levels of PP13 were assessed in four studies but these were variable; and meta-analysis was performed on seven studies. Sensitivity rates of PP13 based on 5% fixed false positive rates were 24%, 45% and 26% for preeclampsia, for early-onset preeclampsia and SGA, respectively. There was no evidence of between-study heterogeneity.

CONCLUSIONS

First trimester PP13, in combination with maternal characteristics and other serum biomarkers was inadequate for screening purposes and predicting women at risk.

A synthesis of existing systematic reviews and meta-analyses of school-based behavioural interventions for controlling and preventing obesity

Schools are an attractive and popular setting for implementing interventions for children. There is a growing body of empirical research exploring the efficacy of school-based obesity prevention programs. While there have been several reviews on the topic, findings remain mixed. To examine the quality of evidence and compare the findings from existing systematic reviews and meta-analyses of school-based programs in the prevention and control of childhood obesity. This paper systematically appraises the methodology and conclusions of literature reviews examining the effectiveness of school-based obesity interventions published in English in peer-reviewed journals between January 1990 and October 2010. Eight reviews were examined, three meta-analyses and five systematic reviews. All of the reviews recognized that studies were heterogeneous in design, participants, intervention and outcomes. Intervention components in the school setting associated with a significant reduction of weight in children included long-term interventions with combined diet and physical activity and a family component. Several reviews also found gender differences in response to interventions. Of the eight reviews, five were deemed of high quality and yet limited evidence was found on which to base recommendations. As no single intervention will fit all schools and populations, further high-quality research needs to focus on identifying specific program characteristics predictive of success.

Trends in overweight and obese adults in Malaysia (1996-2009): a systematic review

Like other nations experiencing rapid industrialization, urbanization and a nutrition transition, there is concern in Malaysia of a possible escalation in the prevalence of overweight and obesity. In 1996, the National Health and Morbidity Survey reported a 16.6% and 4.4% prevalence of overweight and obesity, respectively. In the following decade, there have been several national and community surveys on overweight and obesity in Malaysia. The objective of this systematic review is to describe the trend from 1996 to 2009 in the prevalence of overweight and obesity in adults in Malaysia nationally and by gender, age and race. Results indicate that there has been a small rise in overweight adults in the years 1996, 2003 and 2006 (20.7%, 26.7% and 29.1%) and a much more dramatic increase in obesity in 1996, 2003, 2004 and 2006 (5.5%, 12.2%, 12.3% and 14.0%). Evidence showed a greater risk for overweight and obesity among women compared with men. Based on the highest-quality studies, overweight and obesity levels were highest among adults 40-59 years old. Overweight levels were highest among Indians, followed by Malays, Chinese and Aboriginals, with less consistency across studies on the order of risk or obesity by ethnicity.