Triglycerides (serum) — Trimester-Specific Reference Ranges

Pregnancy is a physiologic hyperlipidemic state. Maternal serum triglycerides rise progressively, especially in the second and third trimesters, driven by estrogen-, progesterone-, and human placental lactogen–mediated changes in lipid metabolism.

  Units Nonpregnant Adult First Trimester Second Trimester Third Trimester
mg/dL < 150 40 – 159 75 – 382 131 – 453
mmol/L < 1.7 0.5 – 1.8 0.9 – 4.3 1.5 – 5.1
Fasting serum triglycerides. Pregnancy-associated increases may be 2–3 fold above nonpregnant values, especially in late gestation.
Physiologic changes in triglycerides during pregnancy
  • Rising estrogen and progesterone increase hepatic synthesis of very-low-density lipoprotein (VLDL), which transports triglycerides.
  • Human placental lactogen and insulin resistance in late pregnancy favor lipolysis and mobilization of maternal triglyceride stores to support fetal and placental energy needs.
  • Total cholesterol, LDL, and especially triglycerides rise throughout gestation, peaking in the third trimester; levels usually return toward baseline postpartum.
  • Although elevations are physiologic, very high triglyceride levels (> 500–1000 mg/dL) increase the risk of acute pancreatitis and may warrant treatment.
Causes of elevated (high) triglycerides

Hypertriglyceridemia may be physiologic in pregnancy or reflect underlying disease:

  • Physiologic pregnancy hyperlipidemia (especially in the third trimester).
  • Obesity and metabolic syndrome.
  • Diabetes mellitus (pre-existing or gestational) and insulin resistance.
  • Familial hypertriglyceridemia or combined hyperlipidemia.
  • Hypothyroidism, nephrotic syndrome, chronic kidney disease, chronic liver disease.
  • Excess alcohol intake.
  • Medications: estrogens (including oral contraceptives prior to pregnancy), glucocorticoids, beta-blockers (non–ISA), thiazide and loop diuretics, atypical antipsychotics, some antiretrovirals, and retinoids.
  • Acute or recurrent pancreatitis can both result from and worsen severe hypertriglyceridemia.
Causes of low triglycerides

Low triglyceride values are less common and often reflect nutritional or systemic conditions:

  • Malnutrition, severe calorie restriction, or very low–fat diets.
  • Malabsorption (celiac disease, inflammatory bowel disease, pancreatic insufficiency, prior bariatric surgery).
  • Hyperthyroidism or other hypermetabolic states.
  • Chronic systemic illness, advanced liver disease, or chronic infection/inflammation.
  • Lipid-lowering therapy (fibrates, high-dose omega-3 fatty acids, statins in the nonpregnant state).
  • Rare genetic hypolipidemias (e.g., abetalipoproteinemia, familial hypobetalipoproteinemia).
References
  1. Abbassi-Ghanavati M, Greer LG, Cunningham FG. Pregnancy and laboratory studies: a reference table for clinicians. Obstet Gynecol. 2009;114(6):1326–1331. PMID: 19935037.
  2. Knopp RH, et al. Lipoprotein metabolism in pregnancy. Am J Obstet Gynecol. 1992;167(4 Pt 2):1176–1183.
  3. Herrera E, Ortega-Senovilla H. Lipid metabolism during pregnancy and its implications for fetal growth. Curr Pharm Biotechnol. 2014;15(1):24–31.
  4. Kratz A, Ferraro M, Sluss PM, Lewandrowski KB. Laboratory reference values. N Engl J Med. 2004;351(15):1548–1563. PMID: 15470219.