Supplemental Table 1.
Normal laboratory reference ranges in pregnant women by trimester
| First trimester | Second trimester | Third trimester | Threshold used as abnormala | |
|---|---|---|---|---|
| White blood cell count, 103/μL | 5.7–13.6 | 5.6–14.8 | 5.9–16.9 | ≤5.6 |
| Aspartate aminotransferase, units/L | 3–23 | 3–33 | 4–32 | ≥33 |
| Troponinb, ng/mL | Not reported | Not reported | 0–0.06a | ≥0.06 |
| D-dimer, μg/mL | 0.2–1.2 | 0.4–3.3 | 0.6–3.3 | ≥3.3 |
| C-reactive protein, mg/L | Not reported | 0.4–20.3 | 0.4–8.1 | ≥20.3 |
| Creatinine, mg/dL | 0.4–0.7 | 0.4–0.8 | 0.4–0.9 | >0.9 |
| Prothrombin time, s | 9.7–13.5 | 9.5–13.4 | 9.6–12.9 | >13.5 |
The normal laboratory reference ranges by trimester were extracted from a comprehensive review of maternal laboratory values in uncomplicated pregnancies derived from approximately 70 references1 with the exception of D-dimer. For D-dimer values, we used a higher laboratory reference range2 to take a more conservative approach to determination of abnormal values in pregnancy.
Lokken et al. COVID-19 in pregnant women in Washington State. Am J Obstet Gynecol 2020.
We applied a single threshold to identify abnormal values, which reflected either the lowest or highest value in the reference range from the second and third trimesters, as appropriate for evaluating the severity of COVID-19 disease.
Troponin level in the third trimester denotes a reference range for an intrapartum value.