Sex of Infant linked to Exposure to PCBs in Uterus

Dr. Randy Morris

Sex of Infant linked to Exposure to PCBs in Uterus

Dr. Randy Morris

With the changing environment and the continual development of new products with new materials, it is no surprise that people are more worried about their exposure to chemicals than ever. Chemicals are in everything we use. Some of these chemicals can have certain adverse effects on infertility, miscarriage or even the success of treatments such as IVF that have yet to be determined.


Polychlorinated Biphenyls are one example of these types of chemicals. PCBs are added to everything from plastics, PVC, paints, coolants, and are found in human fatty tissue. These PCBs accumulate in the body over time. The most common known health effects include skin conditions, liver damage, immune deficiencies, and possibly cancer.

Sex Linkage

A possible recent health effect of PCBs, however, may occur from exposure to fetuses in the uterus during pregnancy. The study from Environmental Health suggests that an increase in exposure to PCBs during pregnancy may lead to a lesser chance of giving birth to a boy. Some theories have been suggested as to how this works. Researchers believe that high maternal PCB concentrations may result in either a favor of “female” sperm concentration or a selective increase in miscarriage of male fetuses.

The study stored blood serum samples taken from women enrolled in a Child Health and Development study during the 1960s. The nearly 400 frozen samples were thawed and analyzed for 11 types of PCBs. The sex of the baby born was compared to the maternal concentration of PBCs in the blood serum.


The results showed that for women who had the highest 10% of total PCBs levels compared to women in the lowest 10th percentile, the chance of a male birth decreased by 33%. This means that with every 1μg/ml increase in PCB concentration in a pregnant woman’s blood, the chances of a male birth decreased by about 7%. Although not all 11 of the PCBs had statistically significant results suggesting these facts, the trend was still evident.


There are other toxic substances like PCBs found in everyday items. Polybrominated diphenyl ethers or PBDEs are used in things like flame-retardants, plastics, foams, and textiles. While we don’t know exactly how substances like PCBs work or affect our health, it is important to understand the risks involved. Women who are pregnant should try to avoid paints, pesticides, cleaning products, carcinogens, and other harmful chemicals that could be dangerous to the mother and the fetus.