Trimester-Specific Reference Ranges
Total testosterone increases as pregnancy progresses due to rising maternal androgen production and increased SHBG.
| Units | Non-pregnant Female | 1st Trimester | 2nd Trimester | 3rd Trimester |
|---|---|---|---|---|
| ng/dL | 6 – 86 | 26 – 211 | 34 – 243 | 63 – 309 |
| nmol/L | 0.21 – 2.98 | 0.9 – 7.32 | 1.2 – 8.4 | 2.2 – 10.7 |
Physiologic Changes in Pregnancy
- Maternal ovary and placenta contribute to increasing androgen levels.
- SHBG rises 2–3×, increasing total testosterone but limiting free testosterone.
- Placental aromatase converts maternal androgens to estrogens.
- Third-trimester testosterone may be 3–5× higher than baseline.
Causes of Elevated Testosterone
- PCOS
- Gestational luteoma
- Hyperreactio luteinalis
- Androgen-secreting ovarian or adrenal tumors
- Congenital adrenal hyperplasia
- Cushing syndrome
- Exogenous androgens / anabolic steroids
Causes of Low Testosterone
- Adrenal insufficiency
- Hypopituitarism
- Severe illness or malnutrition
- Chronic glucocorticoid therapy
- Opioid use
References
- Abbassi-Ghanavati M, Greer LG, Cunningham FG. Pregnancy and laboratory studies: a reference table. Obstet Gynecol. 2009;114:1326–1331.
- O’Leary P, et al. Longitudinal assessment of reproductive hormones during pregnancy. Clin Chem. 1991;37:667–672.
- Kratz A, et al. Laboratory reference values. N Engl J Med. 2004;351:1548–1563.
- Lockitch G. Handbook of Diagnostic Biochemistry and Hematology in Normal Pregnancy. CRC Press.