Father’s Exposures: Should You Worry About Your Pregnancy?

Considering tobacco, alcohol, various drugs and other chemical agents, and high doses of ionizing radiation that one might receive, particularly in the setting of cancer therapy, you may be quite aware that what harms a mother can harm her baby. But, what about paternal exposures, exposure of your male partner to potentially harmful chemical, biological, and physical phenomena prior to conception? Is there any reason to be concerned?

This depends on the drug, environmental chemical, or other agent in question. When it comes to most medications and chemical agents, paternal exposure is not an issue for your pregnancy. For many agents, such as heavy metals, organic pollutants, and other environmental agents called phenols and phthalates, concern about effects in men is greatest surrounding the question of whether the agent might make it more difficult for you to become pregnant, rather than whether there will be a problem with the pregnancy or the baby. But for other agents, doctors and researchers have some concern about the potential for genetic damage in sperm cells that can lead to the pregnancy ending early by way of spontaneous abortion (miscarriage), or that can lead to birth defects.

On the biological side, infectious agents to which a father may have been exposed, such as viruses, can be a problem, since they can transfer to the mother and affect the baby. One key example is Zika virus. A man who is infected with Zika virus can transfer the virus to the female partner. This can happen at the time that he impregnates her, or it can happen before or after that time. Once the mother is infected, there is an elevated risk of birth defects. In particular, Zika virus infection in the mother can lead to a malformation called microcephaly. This means that the baby has a very small head size and that the size of the brain is reduced notably.

Suppose you did give birth to a baby with microcephaly. How would you know if the baby’s father was the cause due to Zika virus? Well, the usual way to be infected with Zika is through the bite of an Aedes aegypti mosquito, which only inhabit particular regions of the world. If your husband, travels to Brazil, for instance, while you remain in a cold city, such as Chicago or Seattle, where A. aegypti does not live, and then later you have a baby with microcephaly, the possibility of a Zika infection certainly would come up in conversations with your doctors. Although, Zika infection often gives nonspecific flu-like symptoms, not everybody will realize that they have a viral infection, if they do not develop complications.

Exposure of the father to certain agents prior to conception has been linked to in increased rate of occurrence of spontaneous abortion (miscarriage). One chemical agent that has a well established association with spontaneous abortion is formaldehyde, a common chemical used in numerous industrial processes. Although a connection is less certain compared with formaldehyde, paternal exposure to lead and mercury are also reported to increase the risk of spontaneous abortion.

Although mostly considered as a well-established cause of male infertility, as it can damage sperm cells, such that they die, or cannot swim well enough to fertilize an ovum (egg), there is some concern that high doses of ionizing radiation exposure in a male may possibly lead to birth defects in his children. By ionizing radiation, we are talking about radiation that interacts with atoms in ways that cause the atoms to lose electrons. This leads the atom to become electrically charged. Depending on the type of ionizing radiation, the DNA of chromosomes can be affected, either from direct interactions with the radiation, or more often through indirect interactions. However, harm occurs only when the dose of ionizing radiation is fairly high. In recent years, scientists have been learning that low doses of ionizing radiation are not harmful, and may actually produce some benefits. Thus, there is nothing to worry about, if, for instance, your male partner has some occupational radiation exposure, such as from working in a nuclear power plant, or around sources of medical ionizing radiation. The concern is connected only with very high doses, such as doses given during radiation therapy to cancer patients but, even then, body parts away from the tumor are shielded. Also, you should keep in mind that radio and microwave transmission used in cellular phone networks is non-ionizing radiation, so it will not dislodge electrons in biological tissue that it hits. So don’t worry too much when you hear people talk about cell phones and other wireless devices emitting “radiation” (visible light is also a kind of radiation, but you’re not worried about that!) On the other hand, sunlight includes ultraviolet radiation, some of which is energetic enough to be ionizing. This is why sunbathing can lead to skin cancer.

Paternal tobacco smoking also can affect the baby in the long-term, not only when the father smokes in the child’s presence after birth. The fetus also can be harmed if the mother is exposed to secondhand smoke from the father, or anyone else who spends a lot of time with her. It has been reported, for instance, that both paternal and maternal smoking raise the risk of childhood obesity.

David Warmflash
Dr. David Warmflash is a science communicator and physician with a research background in astrobiology and space medicine. He has completed research fellowships at NASA Johnson Space Center, the University of Pennsylvania, and Brandeis University. Since 2002, he has been collaborating with The Planetary Society on experiments helping us to understand the effects of deep space radiation on life forms, and since 2011 has worked nearly full time in medical writing and science journalism. His focus area includes the emergence of new biotechnologies and their impact on biomedicine, public health, and society.

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