Vaccines and medications during pregnancy seem to inspire more alarm in both patients and medical providers than any travel related issue, even though these are far from the most common or most serious matters we encounter. In fact, it has been estimated that only about 4% of health issues occurring during travel could be prevented by vaccines. Nonetheless, these problems do deserve attention.

When it comes to shots and medications, in our clinic we try to adhere to two general principles.

The first is the principle of avoidance. If you can safely avoid using a particular medicine or getting a vaccine, you should do so.
Sometimes a simple change of itinerary will accomplish this. For instance, if visiting a country where there is malaria you may be able to avoid the parts of the country where this is a problem. Or staying indoors in the evening and living only in lodgings where there are screens on the windows and mosquito nets on the beds may sufficiently reduce your exposure. Other preventive measures may suffice for some of the other disease risks you may encounter.

The second principle, however, is that of comparative risk.

Researchers in most cases cannot ethically do controlled studies on pregnant women to determine if any particular medicine will harm their baby. So we are usually limited to information that has been found out by accident.

Remember that, despite some theoretical risks, there are very few medicines and no currently available vaccines that have any demonstrated risk to a developing fetus. On the other hand, many of the diseases we are trying to prevent are clearly harmful to the fetus and may even cause its death. Therefore, if there is no way to avoid exposure to a given disease, then the medicine or the vaccine is definitely the lesser of two evils.

When dealing with preventive medicines or vaccines, what we often tell our patients is, “Due to lack of data, we cannot guarantee that this medicine will not hurt your baby. But we can assure you that if you don’t take it and you get the disease, that will hurt your baby.”

Another thing to remember is that the medicines that are considered the best for a certain condition in your home country may not even be available in your destination country. Some antibiotics, for instance, are of dubious safety in pregnancy. But in a developing country the newer, safer medicines may not be available. Once again, the principle of comparative risk applies. A drug that may cause harm is better than a disease that definitely will cause harm. This is one more reason, though, to get careful counseling before you go and to take an adequate supply of medicine with you.


There remain, however, two concerns regarding the use of vaccines.

One is that some vaccines may cause a fever. There is some evidence that any rise in body temperature during early pregnancy increases the risk of neural tube defects. The risk is miniscule, however, and appears to be prevented by simply taking adequate prenatal vitamins.

The other concern is whether or not the vaccine will be effective. Pregnancy is a relatively immune suppressed state. There is concern, therefore, that vaccination may not produce an adequate immune response. Even if not, however, when exposure is unavoidable, some protection is probably better than none. But with some vaccines we may recommend a blood test later to see if you have reached the desired level of immunity.

The vaccines that raise the most concern during pregnancy are the “live virus” vaccines. These include vaccines against mumps, measles, rubella (MMR), varicella and yellow fever. The fear is that these viruses may cross the placenta and cause disease in the fetus. Whenever possible, therefore, their use should be avoided during pregnancy. But if you are not immune to these diseases and cannot reliably avoid exposure to them, the vaccine may be preferable to the risk of getting these diseases as the viruses in question are definitely harmful to the developing fetus. Our recommendations in this regard will vary depending on the circumstances.

Insect Repellents

We often tell people that the most dangerous wild animal in the world is the mosquito.

A host of diseases are spread by insects. Probably the most well-known of these is malaria. Other diseases for which the mosquito is the carrier include yellow fever, dengue fever, chikungunya, Zika virus, Japanese encephalitis and West Nile virus. And there are other insects such as ticks, beetles and tsetse flies that spread other diseases. We are often asked, therefore, what insect repellents are effective and how safe they are to use in pregnancy.

Significantly not effective in medical studies are commonly touted remedies such as consuming large amounts of vitamin B or slathering oneself with various topical non-medical preparations. They may be somewhat effective for brief periods of a few minutes, but not sufficient enough to be practical.

As not all repellents are equally effective against various types of insects, what we recommend will vary with your particular itinerary and likely exposure.

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