Swimming in Hawaiʻi During Pregnancy

How Pregnancy Changes Your Risk

Pregnancy involves natural changes to the immune system. The body partially suppresses immune function to prevent rejection of the developing fetus. This immunomodulation means that bacterial infections from contaminated water may be more likely to take hold, symptoms may be more severe, and recovery may take longer compared to a non-pregnant person with the same exposure.

Dehydration from gastrointestinal illness (the most common result of swimming in contaminated water) is particularly concerning during pregnancy. Even mild dehydration can affect amniotic fluid levels and potentially lead to premature contractions. This alone is reason to be more cautious about water quality when pregnant.

Certain infections that might be mild in healthy adults can have more serious implications during pregnancy. Leptospirosis, which is acquired from freshwater in Hawaiʻi, has been associated with adverse pregnancy outcomes. Vibrio infections, while rare, are also more dangerous for immunocompromised individuals.

Which Beaches Are Lowest Risk

The lowest-risk beaches share several characteristics: they are located on dry, leeward coastlines with minimal stream input, have no cesspools in their immediate watershed, receive few or no brown water advisories, and have consistently low Enterococcus counts in DOH testing.

When to Absolutely Avoid the Ocean

Freshwater Leptospirosis — A Particular Danger

Leptospirosis is a bacterial infection acquired from contaminated freshwater — streams, waterfalls, and ponds. Hawaiʻi accounts for approximately 50% of all U.S. cases. The bacteria come from the urine of infected animals (rats, mongooses, pigs, cattle) that washes into waterways.

During pregnancy, leptospirosis is particularly dangerous. The infection can cause high fever, organ damage, and has been associated with adverse pregnancy outcomes. There is no vaccine available for humans.

Practical Tips for Pregnant Beach-Goers

• Check advisories daily — Visit Safe to Swim Hawaii each morning before heading to the beach
• Be extra conservative about rain — Consider waiting 96 hours instead of the standard 72 after heavy rain
• Bring your own water — Stay hydrated with clean water, not ocean water you might accidentally swallow
• Avoid swallowing water — Keep your mouth closed in the surf; avoid body surfing or activities that increase the chance of swallowing water
• Shower immediately after — Rinse with fresh water and soap as soon as you leave the beach
• Know the nearest medical facility — Before your beach trip, identify the closest urgent care and hospital
• Have a lower threshold for seeking care — See a doctor for any symptoms that would normally be wait-and-see
• Inform your doctor about travel — Tell your OB/GYN about your Hawaiʻi trip and ocean swimming plans

Pool Swimming as an Alternative

If water quality conditions are not ideal or you want to avoid the risk entirely, most Hawaiʻi resorts and hotels have well-maintained swimming pools. Chlorinated pool water poses minimal bacterial risk compared to ocean water. Many hotels on the beach offer poolside ocean views — you can enjoy the scenery without the contamination risk.