From the Guidelines
Guideline-directed pre-pregnancy laboratory screenings are primarily focused on screening for gestational diabetes and genetic carrier status.
Key Screenings
- Gestational diabetes screening: Fasting glucose should be measured at the first prenatal visit (no later than 20 weeks’ gestation) 1. A 75-g oral glucose tolerance test (OGTT) should be performed if the fasting glucose concentration is greater than 85 mg per dL (4.7 mmol per L) 1.
- Genetic carrier screening: Carrier testing of prospective parents, including biologic fathers, should be undertaken in the safest and most cost-effective way 1. This is particularly important for genetic conditions that may require testing of parents and other family members to determine reproductive risks.
Patient Selection
- Low-risk women: May be excluded from glucose testing if they meet certain criteria, such as age younger than 25 years, BMI of 25 kg per m2 or less, no history of abnormal OGTT result, and no first-degree relative with diabetes 1.
- High-risk women: Should undergo glucose testing as soon as possible if they have clinical characteristics consistent with a high risk of gestational diabetes, such as marked obesity or a personal history of gestational diabetes 1.
Testing Timing
- First prenatal visit: Fasting glucose should be measured, and genetic carrier screening should be considered 1, 1.
- 24 to 28 weeks’ gestation: Glucola test or OGTT should be performed for women who have not previously been screened for gestational diabetes 1.
From the Research
Guideline-Directed Pre-Pregnancy Laboratory Screenings
The following laboratory screenings are recommended for pregnant women:
- Blood glucose testing to detect gestational diabetes mellitus 2
- Testing for hepatitis B, Chlamydia trachomatis infection, or human immunodeficiency virus infections for women at risk 2
- Alpha fetoprotein testing for detection of neural tube defects 2
- Aneuploidy screening or diagnostic testing, which may include traditional serum analyte screening, cell-free DNA, chorionic villus sampling, or amniocentesis 3
- Carrier screening, which may include testing for genetic disorders such as cystic fibrosis or sickle cell disease 4
Screening Methods and Interpretation
Methods of screenings involve measuring antigen or antibody titers, a combination of antigen/antibody titers, or by specialized genetic tests 5. Providers responsible for pregnant women should be able to identify which diseases they need to screen for and how to interpret the findings 5. Neonatal providers should also be able to interpret the findings and manage neonates appropriately 5.
Recommendations and Guidelines
The American Congress of Obstetricians and Gynecologists recommends that all pregnant women be offered aneuploidy screening or diagnostic testing 3. Recent national society guidelines on prepregnancy genetic screening and prenatal diagnosis for aneuploidy have been published, and obstetric care providers should educate themselves about the most up-to-date recommendations 4. Society guidelines are largely in agreement, but some newer technologies are not yet routinely recommended for widespread use due to lack of clinical trials and validation studies 4.