Seasonal variations in incidence and maternal–fetal outcomes of gestational diabetes

Abstract

Aims To determine whether the neonatal and delivery outcomes of gestational diabetes vary seasonally in the context of a relatively cool temperate climate. Methods A retrospect cohort of 23 735 women consecutively delivering singleton, live‐born term infants in a single tertiary obstetrics centre in the UK (2004–2008) was identified. A total of 985 (4.1%) met the diagnostic criteria for gestational diabetes. Additive dynamic regression models, adjusted for maternal age, BMI, parity and ethnicity, were used to compare gestational diabetes incidence and outcomes over annual cycles. Outcomes included: random plasma glucose at booking; gestational diabetes diagnosis; birth weight centile; and delivery mode. Results The incidence of gestational diabetes varied by 30% from peak incidence (October births) to lowest incidence (March births; P=0.031). Ambient temperature at time of testing (28 weeks) was strongly positively associated with diagnosis (P<0.001). Significant seasonal variation was evident in birth weight in gestational diabetes‐affected pregnancies (average 54th centile June to September; average 60th centile December to March; P=0.027). Emergency Caesarean rates also showed significant seasonal variation of up to 50% (P=0.038), which was closely temporally correlated with increased birth weights. Conclusions There is substantial seasonal variation in gestational diabetes incidence and maternal–fetal outcomes, even in a relatively cool temperate climate. The highest average birth weight and greatest risk of emergency Caesarean delivery occurs in women delivering during the spring months. Recognizing seasonal variation in neonatal and delivery outcomes provides new opportunity for individualizing approaches to managing gestational diabetes.

Approaches to screening for hyperglycaemia in pregnant women during and after the COVID‐19 pandemic

“…3 Large for gestational age was defined as having a birth weight >90 th centile using locally derived standardized centiles adjusted for infant sex and gestational age. 7 T A B L E 2 Characteristics of women included in each dataset Neonatal hypoglycaemia was defined as a capillary blood glucose level <2.6 mmol/l on more than one occasion at least 4 h after birth. Admission to the neonatal intensive care unit (NICU) was defined as admission for 24 h or longer.…”

“…More recently, seasonal differences in OGTT performance have been highlighted: higher ambient temperatures may increase GDM diagnosis by ~30% in the UK summer. 7 Pre-analytical processing is also critical: a recent Australian study reported that early centrifugation (<10 min) was associated with almost a doubling in GDM diagnoses. 24 A Canadian study found that almost 50% of women with GDM diagnosed using an OGTT were normoglycaemic using capillary glucose monitoring in daily life, emphasizing concerns about sensitivity.…”

“…The alternative strategy recommends glucose testing during other hospital or community appointments to minimize additional clinical contacts. 5 The OGTT has well recognized limitations in terms of test reproducibility, tolerability and seasonal influences, 6,7 but remains the most commonly recommended diagnostic strategy for GDM. 2,3 Excess fetal growth acceleration is detectable from 20 weeks' gestation, predating diagnosis of GDM.…”

Diagnosis of gestational diabetes during the pandemic: what is the risk of falling through the net?

“…In conclusion, such small numbers do not raise great concern and the timing of this predicted period of underdiagnosis fortuitously counteracts the reported tendency to overdiagnose GDM during the hotter months [9]. For these reasons we have implemented the new guidelines and encourage other UK units to do the same.…”

Änderung der GDM-Diagnostik für die Dauer der SARS-CoV-2-Pandemie – wie viele Schwangere fallen durchs Netz?

“…Dieses Ergebnis veranlasste die Autoren, die neuen RCOG-Leitlinien zu implementieren und auch allen anderen Geburtskliniken im Vereinigten Königreich das Gleiche zu empfehlen. Sie führen außerdem an, dass saisonale Schwankungen der GDM-Häufigkeit mit einer Zunahme um 30 % in den Sommermonaten im Vergleich zu den übersehenen Fällen zu einer deutlich höheren Überdiagnose (falsch positiv) führen würden [4].…”