Whether to test for GDM is a common quandary in ob/gyn practice. This article will help you make evidence-based decisions about which patients to test and which assay to use.
Gestational diabetes mellitus (GDM) is common and complicates approximately 4% of all pregnancies in the United States.1 It is defined as carbohydrate intolerance of variable severity that begins or is first recognized during the index pregnancy.2 This definition applies even if the woman is not treated with insulin and her condition persists after pregnancy. Although GDM typically develops during the second half of pregnancy, the glucose intolerance may actually have preceded conception.2
Our current criteria for screening and diagnosing GDM are based on the landmark epidemiologic studies of O'Sullivan and colleagues.4,5 Originally designed to identify a subset of pregnant women at increased risk for developing type 2 diabetes later in life, their criteria were validated by the ability to predict that 22.6% of women would develop glucose intolerance when not pregnant after 8 years and 60% after 16 years. In the past, clinical and historical risk factors were used as indicators for oral glucose tolerance testing (OGTT) in pregnancy. But factors such as giving birth to a previous macrosomic infant, family history of diabetes, obesity, excessive weight gain during pregnancy, glycosuria, proteinuria, and hypertension have been found to capture only about 50% of cases of GDM.6 Therefore, since the 1980s, the 50-g glucose challenge has been routinely used in North America to identify women who warrant diagnostic testing for GDM.
In the US, screening for GDM consists of a 50-g oral glucose load, followed an hour later by plasma glucose determination. The test is performed without regard to the time of day or interval since the last meal. Screening is recommended between 24 and 28 weeks' gestation in women not known to have diabetes mellitus. This approach is endorsed by the American College of Obstetricians and Gynecologists, the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, the North American Diabetes in Pregnancy Study Group (NADPSG), and the Fourth International Workshop Conference on Gestational Diabetes Mellitus.2
In 1966, the 4th International Workshop Conference recommended that a risk assessment for GDM be conducted at the first prenatal visit. Furthermore, they recommended screening women who were considered to be at high risk for GDM as soon as possible, while those at average risk could be tested at between 24 and 28 weeks' gestation.
Cesarean delivery reduces mortality risk in preterm breech births
December 2nd 2024In a recent study, infants born very preterm or extremely preterm had reduced odds of mortality when cesarean delivery was chosen as the mode of delivery, without a notable increase in any morbidity risk.
Read More
Early preterm birth risk linked to low PlGF levels during pregnancy screening
November 20th 2024New research highlights that low levels of placental growth factor during mid-pregnancy screening can effectively predict early preterm birth, offering a potential tool to enhance maternal and infant health outcomes.
Read More
Major congenital malformations not linked to first trimester tetracycline use
November 20th 2024A large population-based study found that first-trimester tetracycline exposure does not elevate the risk of major congenital malformations, though specific risks for nervous system and eye anomalies warrant further research.
Read More
No link found between prenatal cannabis use and childhood developmental delay
November 5th 2024In a recent study, offspring of women with cannabis use in early pregnancy confirmed by self-report or toxicology test were not at an increased risk of childhood early developmental delay up to the age of 5.5 years.
Read More
Prenatal cannabis use not linked to offspring ASD development
November 1st 2024In a recent study, adjustments for maternal characteristics mediated the association between maternal prenatal cannabis use and offspring autism spectrum disorder, indicating no statistically significant increase in risk.
Read More