Is krill oil safe during pregnancy?

What does the evidence say about krill oil during pregnancy?

1. LactMed's monograph on marine oils notes that nursing mothers are generally advised to get 250 to 375 mg a day of combined DHA and EPA, and describes a small study in which eight breastfeeding women took a combined fish oil and krill oil supplement providing 250 mg of DHA and 70 mg of EPA a day for 30 days. 1
2. Unlike fish oil, whose DHA and EPA are mostly bound to triglycerides, the DHA and EPA in Antarctic krill oil are bound to phospholipids, which researchers in a breastfeeding feasibility study suggested may be linked to better absorption, though the study was too small to separate krill oil's individual effect from the fish oil it was combined with. 2
3. A study of 573 patients on the blood thinner warfarin, 145 of whom also took fish oil or krill oil supplements, found no significant difference in time spent in the target anticoagulation range or in major and minor bleeding rates between supplement users and non-users. 3
4. Omega-3 fatty acid supplements, a category that includes krill oil, can cause platelet dysfunction and raise bleeding risk as a side effect, a concern that matters most for anyone already taking anticoagulant or antithrombotic medication. 4
5. A toxicological assessment of commercial krill oil products found their PCB levels were lower than most fish oil products tested, using 0.015 to 0.034 percent of the tolerable daily intake compared with up to 0.83 percent for some fish oils, but the same krill oil products measured higher than most fish oils for a different pollutant class called chlorobenzenes, and none of the products analyzed came close to exceeding tolerable daily intake limits for any single contaminant at the highest recommended dose. 5

Is krill oil safe in each trimester?

• First trimester. DHA needs early in pregnancy are similar to what they were before you conceived, so there's no urgency to start krill oil specifically. Because krill oil has not been directly studied in pregnant women, the first trimester is a good time to run any new supplement, krill oil included, by your healthcare provider before starting.
• Second trimester. As your baby's brain and nervous system develop through the second trimester, steady omega-3 intake matters, but the research supporting that comes mostly from fish oil and algal oil, not krill oil specifically. If you're already using krill oil, mention it at your next appointment, especially if you take a blood thinner or have a bleeding-related condition.
• Third trimester. Omega-3 needs stay elevated through the third trimester as brain growth continues. Krill oil's DHA and EPA are similar to fish oil's, but because pregnancy-specific human data is limited to small studies in breastfeeding mothers rather than pregnant women, a fish oil or algal-oil supplement with a longer pregnancy safety track record may be the more cautious choice this late in pregnancy.