Researchers have just discovered that paternal exposure to phthalates, common chemicals found in plastics, correlates with lower embryo quality. Fathers with high urinary phthalate concentrations affected a specific stage of embryonic development. The findings are in a paper that was just published in the journal Human Reproduction.
Most studies about parental effects on embryonic and fetal development focus on the mother. After all, the embryo will be developing in her body and any chemicals she’s exposed to may affect the growing fetus. However, scientists are now beginning to study the effects of the father and his sperm. If a father’s sperm becomes damaged due to chemical exposure or physical problems, it makes sense that it may affect the quality of the eventual embryo.
A team of scientists from the University of Massachusetts Amherst investigated the potential effects of parental phthalate exposure on embryonic development. Phthalates are very common chemicals found in many plastics and personal care products. The research team studied 50 couples undergoing In Vitro Fertilization (IVF) treatment and collected a total of 761 oocytes—egg cells destined to become embryos after fertilization. The team then observed the development of these cells while also taking urine samples from both the men and women. This allowed the researchers to check phthalate concentrations. 423 of the oocytes managed to make it to the next stage of development and the team recorded blastocyst (the day five stage of embryonic development) quality.
The team found that fathers, but not mothers, with high phthalate concentrations negatively affected embryonic development. Specifically, embryos from these fathers were more likely to have trouble developing at the blastocyst stage. No other stage of development was affected.
The findings point to a link between paternal exposure to phthalates and poor blastocyst development. The authors acknowledge that more research is needed but that it’s becoming clear that fathers do contribute to the health of the embryo during conception.
Wu et al. Parental contributions to early embryo development: influences of urinary phthalate and phthalate alternatives among couples undergoing IVF treatment. Human Reproduction (2016).