I once had a patient ask me if there was any harm in eating eight lobsters during her week long vacation in Maine. She was six weeks pregnant at the time and was concerned about the potential effects of mercury on the development of her baby.

After marveling at the fact that she could afford eight lobsters in one week, I reassured her that this should have no effect on fetal development, as lobster is not one of the sea creatures we associate with high mercury levels.

The patient’s question may seem outrageous to some, but to me it was just another inquiry from another mother trying to do what is best for her baby.

In our last post, we discussed the effects of exposures that are more routinely associated with a potential negative effect on the development of an embryo. Below is information on some of the most common everyday exposures that I’ve been asked about:

Methylmercury is a toxic form of mercury found most often in water, soil, plants, and animals. You can be exposed to methylmercury by eating contaminated fish. According to the FDA, women who are planning to become pregnant within one year, pregnant women, and nursing mothers should avoid fish that contain high levels of methylmercury.

Shark, swordfish, king mackerel and tilefish (it’s okay to click the link, I had no idea what it was either) are the typical varieties to avoid during pregnancy. Further information, including the recommended amount of fish consumption and the potential effects of high mercury levels during pregnancy, can be found here.

Pesticides, in general, have not been associated with an increased risk for birth defects. But researchers are still debating whether or not pesticide exposure during pregnancy increases the risk of childhood cancer. If you are worried about potential risks, please refer to this fact sheet.

Paint exposure, or rather the effects thereof, is another big topic for prospective parents. Questions are mostly in the context of “Can I paint my child’s room?”, though for the die-hard DIY-ers, it may extend to larger projects. The potential effects of paint exposure during pregnancy are influenced by:

  • the method of contact, such as inhalation of vapors and fumes, absorption through the skin, or ingestion of paint chips and dust
  • length of exposure
  • paint content (Does the pain contain toluene?)

Of note, the exact level of paint exposure is usually not known in any given case. Thus studies looking at paint exposure during pregnancy have not had consistent results. You can find recommendations on how to limit your exposure during pregnancy, here.

Whether you are attempting to get pregnant or are currently pregnant, you worry about the health and development of your baby. While there are certainly many exposures to avoid, many common concerns are really not much to worry about at all. If you have any questions, don’t hesitate to touch base with your healthcare provider, a local genetic counselor, or visit MotherToBaby online.


Shannon Wieloch

Shannon Wieloch is a licensed board-certified genetic counselor at CooperGenomics. Her primary responsibility is to provide genetic counseling to CooperGenomics patients. Other professional roles include managing the genetic content on social media, supervising graduate students, and conducting research.

Prior to joining CooperGenomics, Shannon worked in cardiac research at The Children’s Hospital of Philadelphia and in prenatal genetic counseling at The Delaware Center for Maternal and Fetal Medicine. She received a dual B.S. in biology and psychology from The University of Pittsburgh and her M.S. in genetic counseling from Arcadia University. Her passion is to provide comprehensive genetic education to medical professionals, patients, and the general public. In her free time, she loves to travel, doodle, play board games with her girls, and take too many pictures of her cat.